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Toro Zero Turn smoking
#1
C
Cboy553
C
Cboy553
I work at a rental shop and just tore down a zero turn replaced rings and head gasket. Was burning oil badly like a quart an hour. Well now it smokes on start up for about a minute. Well I realize I had oil in the carb so I let it run half an hour. Anyway it still smokes on start up. Any ideas thank
#2
M
mechanic mark
M
mechanic mark
Check air filter for replacement, may be stopped up & not letting engine breathe. Check hose from air filter to reed valve at valve cover & reed valve itself if applicable. Did you drain oil from engine before disassembly on workbench? Check oil level on dipstick & see if it smells like gasoline. thanks, Mark
Post engine make & all information from engine, thanks,Mark
www.toro.com
Post engine make & all information from engine, thanks,Mark
Parts | Toro
www.toro.com
#3
C
Cboy553
It’s a Briggs and Stratton 74350
C
Cboy553
Yeah I drained it. Cleaned the block really well. I honed it but my boss says it’s probably not honed very wellCheck air filter for replacement, may be stopped up & not letting engine breathe. Check hose from air filter to reed valve at valve cover & reed valve itself if applicable. Did you drain oil from engine before disassembly on workbench? Check oil level on dipstick & see if it smells like gasoline. thanks, Mark
Post engine make & all information from engine, thanks,Mark
It’s a Briggs and Stratton 74350
#4
B
bertsmobile1
B
bertsmobile1
Could be a bad hone but usually that would smoke all the time
Does it smoke on every start, hot or cold or only on a cold start ?
Did you replace the inlet valve oil seal ?
As a general rule
bad rings / worn bore smokes on acceleration
Bad vales smoke on the over run
So you grab the governor arm and work the governor between wide open and down the the idle stop
Don't over do the WFO bit
And don't rule out a head gasket leak unless you have done a leak down test .
If you installed the rings very wet it can take a few hours for the rings to bed in
If you installed them dry then they should have bedded in within a few minutes
Does it smoke on every start, hot or cold or only on a cold start ?
Did you replace the inlet valve oil seal ?
As a general rule
bad rings / worn bore smokes on acceleration
Bad vales smoke on the over run
So you grab the governor arm and work the governor between wide open and down the the idle stop
Don't over do the WFO bit
And don't rule out a head gasket leak unless you have done a leak down test .
If you installed the rings very wet it can take a few hours for the rings to bed in
If you installed them dry then they should have bedded in within a few minutes
#5
C
Cboy553
C
Cboy553
Well it seems to smoke in both work or cold. And it only lasts about 30-40 seconds and clears up. If I shut off the motor and start right back up won’t smoke. If I wait about 10+ minutes before firing it up again then it’ll smoke
#6
B
bertsmobile1
B
bertsmobile1
That is oil leaking under gravity down the valve stems most likely
If it clears up after a couple of seconds the it is nothing to be worried about
If it clears up after a couple of seconds the it is nothing to be worried about
#7
C
Cboy553
C
Cboy553
Problem is the boss ain’t happy and tells me the mower ain’t leavin the shop till it starts without smokin. Would a new head clear it up?That is oil leaking under gravity down the valve stems most likely
If it clears up after a couple of seconds the it is nothing to be worried about
#8
B
bertsmobile1
B
bertsmobile1
Well if he wants it to run like a new engine then it will need a rebore and new valve guides which means a new head
Or to put it another way
A new engine
Don't know how you can tell this to your boss without getting fired but it is an old machine
If the bore / rings was worn to the extent of a quart an hour then it needed a rebore and most mower engines do not have oversized pistons available anymore .
Or to put it another way
A new engine
Don't know how you can tell this to your boss without getting fired but it is an old machine
If the bore / rings was worn to the extent of a quart an hour then it needed a rebore and most mower engines do not have oversized pistons available anymore .
#9
C
Cboy553
C
Cboy553
I think it needs a head replacement myself. I’m going to pitch it to him. The reason it was brought in to us was it was smoking badly and burning a quart an hour. So I think it’s doing fantastic compared to what it was. In my opinion I think the valves are the problem now.Well if he wants it to run like a new engine then it will need a rebore and new valve guides which means a new head
Or to put it another way
A new engine
Don't know how you can tell this to your boss without getting fired but it is an old machine
If the bore / rings was worn to the extent of a quart an hour then it needed a rebore and most mower engines do not have oversized pistons available anymore .
#10
7394
7394
Did you replace the valve seals ?
#12
Smithsonite
Smithsonite
Smoke at startup is a dead ringer for a leaky valve seal. The few drips that get past it burn up after startup, so it'll puff for a second or 2 after starting.
#13
Dreaded
Dreaded
I have seen one that smoked on start up after setting a while. It turned out to be fuel smoke because it was carb leaking slowly into the intake. It was a light blueish smoke.
#14
S
sterobinson
S
sterobinson
I'm not sure which engine but some have a Reed valve under the flywheel that leak also.
#15
grumpyunk
grumpyunk
Symptoms point to valve stem seal leakage, or worn valve guides. Mostly intake valve stem seals will allow oil into the intake when vacuum is high, or given time for oil to seep down the guide around the stem.
If you did not replace the valve stem seals, it would be a decent bet that doing so might cut out the blue smoke on startup. You can do it without removing the cylinder head. Feed a length of rope into the spark plug hole, and then rotate the crankshaft to have the piston hold the valves closed. Pop off the rocker arm and valve spring, pry off the old seal and put on the new one. I'd apply a bit of oil to ease the seal over the valve stem tip. Replace the spring & keepers, and the rocker arm. Remove the rope, replace the plug, and see what happens. You will have to insure the crankshaft does not rotate once you have placed the rope and blocked the valves from falling into the cylinder. Clamp the flywheel or the pulley on the PTO.
tom
If you did not replace the valve stem seals, it would be a decent bet that doing so might cut out the blue smoke on startup. You can do it without removing the cylinder head. Feed a length of rope into the spark plug hole, and then rotate the crankshaft to have the piston hold the valves closed. Pop off the rocker arm and valve spring, pry off the old seal and put on the new one. I'd apply a bit of oil to ease the seal over the valve stem tip. Replace the spring & keepers, and the rocker arm. Remove the rope, replace the plug, and see what happens. You will have to insure the crankshaft does not rotate once you have placed the rope and blocked the valves from falling into the cylinder. Clamp the flywheel or the pulley on the PTO.
tom
#17
C
Cboy553
C
Cboy553
Compression is fine. Don’t have the means for a leak test I don’t think.Why not test before teardown?
Compression test
Leakdown test?
#18
K
kenn_chan
K
kenn_chan
Tomw0 is I feel on the correct path. if you swap out the valve guide seals and it stops smoking and then starts smoking again in a month or two then you have worn guides as well if thats the case its probably cheaper to just replace the engine.
#19
C
Cboy553
C
Cboy553
Unfortunately that’s not an option. The customer priced an engine at 1250 after freight. And wants this one rebuilt etc. this is a huge headacheTomw0 is I feel on the correct path. if you swap out the valve guide seals and it stops smoking and then starts smoking again in a month or two then you have worn guides as well if thats the case its probably cheaper to just replace the engine.
#20
grumpyunk
cylinder head complete ... $213.xx .... lots less than $1250. If the customer wants it to work properly and will not stand for a slight puff of smoke on startup, then it will cost at least this much to replace the head. Doing the valve stem seal(s) may reduce the puffing. An alternative is to have the valve guides reamed or drilled and new guides pressed into the cylinder head. Then ream the guides to the proper size to fit the valve stem diameter. All of that labor will likely be more than a new cylinder head.
A second alternative, or third.. fourth... would be to find a used head that was in better shape.
I am not on the clock, so I would have taken the head apart when I had it that far, and checked the condition of the valve seats, the fit of the stem to the guide, and certainly replaced the seal. If you want no smoke, you will have to do the 'rope' thing, or remove the head and refurbish is or replace it.
I see no alternatives...
tom
grumpyunk
cylinder head complete ... $213.xx .... lots less than $1250. If the customer wants it to work properly and will not stand for a slight puff of smoke on startup, then it will cost at least this much to replace the head. Doing the valve stem seal(s) may reduce the puffing. An alternative is to have the valve guides reamed or drilled and new guides pressed into the cylinder head. Then ream the guides to the proper size to fit the valve stem diameter. All of that labor will likely be more than a new cylinder head.
A second alternative, or third.. fourth... would be to find a used head that was in better shape.
I am not on the clock, so I would have taken the head apart when I had it that far, and checked the condition of the valve seats, the fit of the stem to the guide, and certainly replaced the seal. If you want no smoke, you will have to do the 'rope' thing, or remove the head and refurbish is or replace it.
I see no alternatives...
tom
#21
C
Cboy553
C
Cboy553
Well that’s what I’ll do then. Replace the head.
cylinder head complete ... $213.xx .... lots less than $1250. If the customer wants it to work properly and will not stand for a slight puff of smoke on startup, then it will cost at least this much to replace the head. Doing the valve stem seal(s) may reduce the puffing. An alternative is to have the valve guides reamed or drilled and new guides pressed into the cylinder head. Then ream the guides to the proper size to fit the valve stem diameter. All of that labor will likely be more than a new cylinder head.
A second alternative, or third.. fourth... would be to find a used head that was in better shape.
I am not on the clock, so I would have taken the head apart when I had it that far, and checked the condition of the valve seats, the fit of the stem to the guide, and certainly replaced the seal. If you want no smoke, you will have to do the 'rope' thing, or remove the head and refurbish is or replace it.
I see no alternatives...
tom
#22
grumpyunk
grumpyunk
Note: I did NOT check any source for availabiltiy, nor did I do ANY price shopping. That is beyond my level of interest & knowledge.
tom
tom
#23
C
Cboy553
C
Cboy553
It’s all good though. I think the boss knows it’s not the honing. He suggested it was rings and was wrong. He probably trying make it look like I messed it up. But I don’t care. I have the green light on the head replacement from customer. So that’s that.Note: I did NOT check any source for availabiltiy, nor did I do ANY price shopping. That is beyond my level of interest & knowledge.
tom
#24
sgkent
sgkent
typically consistent oil smoke on start up on an engine is oil leaking down from valve guides. Either worn or seals (if any) worn. Make sure the breather is open. I had a shop assign me a job to replace cam seals on a twin OHC engine. The shop foreman sold the guy on the new cam seals and gaskets. I did the work, and it was back in a day. No one told me what the guy's actual complaint was. He was complaining about oil leaks and smoking. Once I knew what his complaint was took about 5 minutes to clean the breather screen that was plugged.
#25
C
Cboy553
C
Cboy553
That’s interesting I’ll have to look into that as well then. Thanks mantypically consistent oil smoke on start up on an engine is oil leaking down from valve guides. Either worn or seals (if any) worn. Make sure the breather is open. I had a shop assign me a job to replace cam seals on a twin OHC engine. The shop foreman sold the guy on the new cam seals and gaskets. I did the work, and it was back in a day. No one told me what the guy's actual complaint was. He was complaining about oil leaks and smoking. Once I knew what his complaint was took about 5 minutes to clean the breather screen that was plugged.
#26
doug9694
doug9694
May be breather valve. Try temporarily disconnecting the breather tube. Or may be a warped head allowing oil to get sucked in.I work at a rental shop and just tore down a zero turn replaced rings and head gasket. Was burning oil badly like a quart an hour. Well now it smokes on start up for about a minute. Well I realize I had oil in the carb so I let it run half an hour. Anyway it still smokes on start up. Any ideas thank
#27
R
RGSERVICES
R
RGSERVICES
if on start up : valve stem seals, if smokes a short while after start up (usually increasing) : oil control ring / wiper ring. that is the general rule, what colour is the smoke? it maybe fuel and not oil at all! the float needle may not be sealing fully which would allow fuel to run into the cylinder (via atmospheric pressure / gravity) so effectively you are starting a slightly flooded engine - if that were the case the smoke would clear very quickly, the question is what colour smoke have you got black = fuel, blue/grey sometimes referred to as white = oilI work at a rental shop and just tore down a zero turn replaced rings and head gasket. Was burning oil badly like a quart an hour. Well now it smokes on start up for about a minute. Well I realize I had oil in the carb so I let it run half an hour. Anyway it still smokes on start up. Any ideas thank
#28
C
Cboy553
C
Cboy553
White.if on start up and clears : valve stem seals, if from start up and constant (usually increasing) : oil control ring / wiper ring. that is the general rule, what colour is the smoke? it maybe fuel and not oil at all! the float needle may not be sealing fully which would allow fuel to run into the cylinder (via atmospheric pressure / gravity) so effectively you are starting a slightly flooded engine - if that were the case the smoke would clear very quickly, the question is what colour smoke have you got black = fuel, blue/grey sometimes referred to as white = oil
#30
C
Cboy553
C
Cboy553
customer states the mower was parked for two years then when ran it started smoking. He says when oil gets down low enough to the add mark on dip stick then won’t smoke
#31
Woody
Woody
sounds like valve seals to me
#33
grumpyunk
grumpyunk
White smoke is generally NOT caused by oil being burned inside the combustion chamber. You may want to re-think replacing the cylinder head as the cause is likely NOT loose valve seals or guides.
tom
tom
#34
G
Gord Baker
G
Gord Baker
I suspect that the muffler is saturated with oil and it will take some time to burn off.I work at a rental shop and just tore down a zero turn replaced rings and head gasket. Was burning oil badly like a quart an hour. Well now it smokes on start up for about a minute. Well I realize I had oil in the carb so I let it run half an hour. Anyway it still smokes on start up. Any ideas thank
#35
grumpyunk
grumpyunk
What Gord said. Take it out to a field, and put it to work for a half hour or maybe a full hour. Park it, and then start it from cold after it sits for a couple hours or overnight. You may find it has stopped being a juvenile delinquent and has given up smoking completely.
If it had years(hours?) of being fed oil from leaking oil control rings, that will form a coating inside the muffler that will take time to burn off.
Also note that you can get white smoke on ANY engine started from cold if the ambient temperature is cool enough to cause condensation of the vapor in the exhaust gas.
Also note that some are very quick to find inconsequential problems to seize upon as a reason to put down someone else's work. ... And there may be NO solution... as in "that's the way it works, they all do that"
YMMV
tom
If it had years(hours?) of being fed oil from leaking oil control rings, that will form a coating inside the muffler that will take time to burn off.
Also note that you can get white smoke on ANY engine started from cold if the ambient temperature is cool enough to cause condensation of the vapor in the exhaust gas.
Also note that some are very quick to find inconsequential problems to seize upon as a reason to put down someone else's work. ... And there may be NO solution... as in "that's the way it works, they all do that"
YMMV
tom
#36
C
Cboy553
C
Cboy553
Yeah actually I just tore the motor down again and noticed the muffler had what looked like oil resin. And when I start the motor it takes about 10 seconds before it starts to blow smoke. The. It smokes for about 30-40 seconds before it peters out.I suspect that the muffler is saturated with oil and it will take some time to burn off.
#37
C
Cboy553
C
Cboy553
not sure how to upload pics because it keeps saying pics too large for server otherwise I’d love to show you guys what I’m dealing with. Bottom of head I see oil burn marks going up one side of the intake port
#38
grumpyunk
grumpyunk
I have used the PAINT program to lower the size of images. Some sites restrict the size severaly and the only option are to use another web site to hold the pics or reduce their size.
tom
tom
#39
A
Alton R
A
Alton R
You did replace the valve stem seals.I work at a rental shop and just tore down a zero turn replaced rings and head gasket. Was burning oil badly like a quart an hour. Well now it smokes on start up for about a minute. Well I realize I had oil in the carb so I let it run half an hour. Anyway it still smokes on start up. Any ideas thank
#40
S
SJS
As others have noted: New "standard" (STD) rings do not make up for bore wear: They only "assist" in reducing the amount of oil burned.
As for your boss: "You cannot make a silk purse out of a sows ear." He needs to bite the bullet ,as he is obviously not a mechanic.
Good luck.
S
SJS
Well, for me it is the valve guides worn and draining down....Same with any OHV engine.Problem is the boss ain’t happy and tells me the mower ain’t leavin the shop till it starts without smokin. Would a new head clear it up?
As others have noted: New "standard" (STD) rings do not make up for bore wear: They only "assist" in reducing the amount of oil burned.
As for your boss: "You cannot make a silk purse out of a sows ear." He needs to bite the bullet ,as he is obviously not a mechanic.
Good luck.
#41
C
closecut
C
closecut
Sounds like a valve stem seal problem.
Part Number: 690968 (double check this number versus the ENGINE Number on the data plate on the ENGINE).
They are easily damaged when installing,so don't use a screwdriver to work them down over the valve stem.Use the proper tools and do it right.The groove for the retainer can damage the seal if it is forced down over it without the proper tool to ease it over the groove.
Valve Seal
Part Number: 690968 (double check this number versus the ENGINE Number on the data plate on the ENGINE).
They are easily damaged when installing,so don't use a screwdriver to work them down over the valve stem.Use the proper tools and do it right.The groove for the retainer can damage the seal if it is forced down over it without the proper tool to ease it over the groove.
#43
T
TobyU
T
TobyU
Well, first of all I think your boss is being kind of a weirdo expecting so much perfection out of old used worn out parts.
He should realize that's just not possible just like extreme lifespan isn't possible on a lot of this new equipment and you should never expect that or lead your customers to believe you can provide that.
People should also get out of the habit and stop offering engine rebuilds anyways. It's simply not worth it and not even cost-effective for the customer. Neither is a new engine typically because the cheapest you'll ever find one is 850 and most over a $1,000 and these are actually old prices. I haven't checked them recently so who knows what they've gone up to.
There was a time where you could get a 17 or 17.5 horsepower Briggs 31xxxx series on the shelf at rural King for 479 but that was about 6 years ago.
That made it almost feasible but in reality the only cost-effective way to fix one when people say it needs an engine is to put a good used running engine on one.
The only repairs that are feasible to do are blown head gaskets and occasionally a snap rod but even that you're probably almost always going to be cheaper just to get a good used engine and this is sometimes the case even if you're not paying for labor and doing it yourself just because the parts but if you can get lucky and use some erratic acid and or clean up the crankshaft and just replace the one rod even if you have to buy a new rod and the gasket for the sump, you can do it possibly cheaper than buying a good used running engine to slap on the machine.
A lot of those early twins got destroyed because they were sucking dirt in around the air filter and it wiped out the rings for some reason where hardly any of the singles ever had this problem and some people run those without an air filter at all and they still last for many years so I really can't figure that one out but oh well.
Have you actually run this machine and got it good and hot for over 30 to 45 minutes or an hour and actually mow with it??
Lots of times mowers especially push mowers, will get the muffler so full of oil that it will take at least a half an hour running to burn it all out of there.
It sounds like that's probably not your problem but always keep that in the back of your mind.
It's probably valve stem seals and I would pop the springs off by holding the valves in position with either compressed air or rope packed into the cylinder and the piston pushed up slightly and put the good umbrella style valve stem seals on each valve.
I think that's what this engine has anyways but I've been known on cars and some other things that just used a little simple o-ring too double up and put the umbrella style and everything or some other improved design or the small o-ring one plus and umbrella style.
That should fix it and I guess you could turn off the air pressure or back the flywheel down a little bit for the piston and see if the valve stem wobbles too much in the guide because that could be an issue too but probably not the case.
New seals would probably solve the problem but at worst case scenario then you would slap a new head on it or I believe this is a twin so heads.
It's still kind of a crap shoot though because what if it is the actual piston rings and cylinder walls and sealing and you waste the time and money to put two new heads on it??
You could go back to the old school basics and try to do a compression test and a leak down test and then do a wet test with maybe some 40 or 50 weight oil squirted in the cylinder and see if you can determine if it is the rings or the valves or maybe take the valve cover off and look and listen for any air coming around the valve.
It's still a good percentage of guessing and hoping though.
But your boss fails to understand or accept is there really are no exact things in this field.
There are maybe 80th percentile and above but slapping new parts on and boring out cylinders and putting larger Pistons if available or just honing and replacing the rings doesn't always give you 100% results or even 93% results.
He should realize that's just not possible just like extreme lifespan isn't possible on a lot of this new equipment and you should never expect that or lead your customers to believe you can provide that.
People should also get out of the habit and stop offering engine rebuilds anyways. It's simply not worth it and not even cost-effective for the customer. Neither is a new engine typically because the cheapest you'll ever find one is 850 and most over a $1,000 and these are actually old prices. I haven't checked them recently so who knows what they've gone up to.
There was a time where you could get a 17 or 17.5 horsepower Briggs 31xxxx series on the shelf at rural King for 479 but that was about 6 years ago.
That made it almost feasible but in reality the only cost-effective way to fix one when people say it needs an engine is to put a good used running engine on one.
The only repairs that are feasible to do are blown head gaskets and occasionally a snap rod but even that you're probably almost always going to be cheaper just to get a good used engine and this is sometimes the case even if you're not paying for labor and doing it yourself just because the parts but if you can get lucky and use some erratic acid and or clean up the crankshaft and just replace the one rod even if you have to buy a new rod and the gasket for the sump, you can do it possibly cheaper than buying a good used running engine to slap on the machine.
A lot of those early twins got destroyed because they were sucking dirt in around the air filter and it wiped out the rings for some reason where hardly any of the singles ever had this problem and some people run those without an air filter at all and they still last for many years so I really can't figure that one out but oh well.
Have you actually run this machine and got it good and hot for over 30 to 45 minutes or an hour and actually mow with it??
Lots of times mowers especially push mowers, will get the muffler so full of oil that it will take at least a half an hour running to burn it all out of there.
It sounds like that's probably not your problem but always keep that in the back of your mind.
It's probably valve stem seals and I would pop the springs off by holding the valves in position with either compressed air or rope packed into the cylinder and the piston pushed up slightly and put the good umbrella style valve stem seals on each valve.
I think that's what this engine has anyways but I've been known on cars and some other things that just used a little simple o-ring too double up and put the umbrella style and everything or some other improved design or the small o-ring one plus and umbrella style.
That should fix it and I guess you could turn off the air pressure or back the flywheel down a little bit for the piston and see if the valve stem wobbles too much in the guide because that could be an issue too but probably not the case.
New seals would probably solve the problem but at worst case scenario then you would slap a new head on it or I believe this is a twin so heads.
It's still kind of a crap shoot though because what if it is the actual piston rings and cylinder walls and sealing and you waste the time and money to put two new heads on it??
You could go back to the old school basics and try to do a compression test and a leak down test and then do a wet test with maybe some 40 or 50 weight oil squirted in the cylinder and see if you can determine if it is the rings or the valves or maybe take the valve cover off and look and listen for any air coming around the valve.
It's still a good percentage of guessing and hoping though.
But your boss fails to understand or accept is there really are no exact things in this field.
There are maybe 80th percentile and above but slapping new parts on and boring out cylinders and putting larger Pistons if available or just honing and replacing the rings doesn't always give you 100% results or even 93% results.
#44
T
TobyU
T
TobyU
Yes, especially if the fuel is kind of whitish with only a tint of blue when it first comes out and only for two or three seconds. That is a common sign that the carb is continuing to drip inside because the needle and seat are not shutting off properly and you'll get the smoke after it's sat for 10 minutes or longer but it clears right up.I had the exact same issue for years until I installed a fuel line shut-off valve.
#45
S
STEVES
S
STEVES
Well, quick, cheap and then continue on, would be to replace the valve seals. No tear down, put air into spark plug hole after backing off valve lash. piston will go to bottom, then remove intake valve spring and replace seal. Adjust all valves to specs. Like said before run and work engine to clear out muffler. If good = Done. Should always do seals when doing tear down.
#46
G
Gescha
G
Gescha
Change the valve guide seals.I work at a rental shop and just tore down a zero turn replaced rings and head gasket. Was burning oil badly like a quart an hour. Well now it smokes on start up for about a minute. Well I realize I had oil in the carb so I let it run half an hour. Anyway it still smokes on start up. Any ideas thank
#47
T
The Specialist
T
The Specialist
Wow, this is interesting/the advice that is!! I do part agree with the guy about the process that you did on the cylinder. The actual way this ISVs to be done is that you have a boring machine, telescoping gauges and honing stones. Too much to get into here, but you would have been better off to replace the engine. The cylinder head- did you clean up the valves? Usually if the exhaust valve is not seating, a little oil goes into the cylinder head, hence, why you are getting the puff of smoke on start up. I think you are ok on the deglazing of the cylinder, because if you weren’t, it would smoke all the time, but the engine would be noisy. To do the valves, remove cylinder head, take the valves out, put one in a drill mounted in a vide. Get 120 grit emery cloth, and clean them up with the drill spinning. To do the face, come down with the emery cloth on a 45degree angle lightly with the emery cloth until cleaned up. IT is also best to dip the emery cloth in gas before you start.
#48
T
TobyU
I don't actually think I've used Emery cloth on them or sandpaper but I have used the fairly fine wire brush on the grinding wheel to clean them up I do however, recommend using some course grit lapping compound and then some fine grit lapping compound and lap them decently in the head once you do this because you're probably going to round off the sharp angles a little bit even though cleaning up the crap and making the surface smooth probably outweighs any problems you could cause by getting the angles off a little but then when you go and lap them you will be increasing the sealing ability quite a bit.
When I officially opened my shop in 2011 I looked around and thought about buying one of the old school valve grinding apparatuses but found out they're still pretty expensive and I'm a cheapskate and there's not really that big of a demand or need to do it and I don't rebuild inches anyways and most of those jobs that would require that are simply too labor intensive and time involved for me to bother doing when I can sit here all day long doing annual services and carb cleanouts and make a lot more money in less time and help a lot more people overall.
So I gave up on the idea but if I'm ever at a garage sale somewhere and see one that they're basically giving away I will pick it up.
The only time in my life I ever actually used one was in junior high school in the metals and small engine class where are we did a complete rebuild and ground the valves whether they needed it or not.
The fact is, lawn mowers are low performance little turds!
This makes them very forgiving and you just don't see that many burnt valves or valves that really need to be ground.
You find far more popped valve seats and way more slipped valve guides causing valve train issues but it's not the actual valve cut angle sealing surface at all.
T
TobyU
Now you know you're going to make some people's heads spin around talking about cleaning up valves and even daring to mention touching the sealing surface with something so unprecise as your finger!!!Wow, this is interesting/the advice that is!! I do part agree with the guy about the process that you did on the cylinder. The actual way this ISVs to be done is that you have a boring machine, telescoping gauges and honing stones. Too much to get into here, but you would have been better off to replace the engine. The cylinder head- did you clean up the valves? Usually if the exhaust valve is not seating, a little oil goes into the cylinder head, hence, why you are getting the puff of smoke on start up. I think you are ok on the deglazing of the cylinder, because if you weren’t, it would smoke all the time, but the engine would be noisy. To do the valves, remove cylinder head, take the valves out, put one in a drill mounted in a vide. Get 120 grit emery cloth, and clean them up with the drill spinning. To do the face, come down with the emery cloth on a 45degree angle lightly with the emery cloth until cleaned up. IT is also best to dip the emery cloth in gas before you start.
I don't actually think I've used Emery cloth on them or sandpaper but I have used the fairly fine wire brush on the grinding wheel to clean them up I do however, recommend using some course grit lapping compound and then some fine grit lapping compound and lap them decently in the head once you do this because you're probably going to round off the sharp angles a little bit even though cleaning up the crap and making the surface smooth probably outweighs any problems you could cause by getting the angles off a little but then when you go and lap them you will be increasing the sealing ability quite a bit.
When I officially opened my shop in 2011 I looked around and thought about buying one of the old school valve grinding apparatuses but found out they're still pretty expensive and I'm a cheapskate and there's not really that big of a demand or need to do it and I don't rebuild inches anyways and most of those jobs that would require that are simply too labor intensive and time involved for me to bother doing when I can sit here all day long doing annual services and carb cleanouts and make a lot more money in less time and help a lot more people overall.
So I gave up on the idea but if I'm ever at a garage sale somewhere and see one that they're basically giving away I will pick it up.
The only time in my life I ever actually used one was in junior high school in the metals and small engine class where are we did a complete rebuild and ground the valves whether they needed it or not.
The fact is, lawn mowers are low performance little turds!
This makes them very forgiving and you just don't see that many burnt valves or valves that really need to be ground.
You find far more popped valve seats and way more slipped valve guides causing valve train issues but it's not the actual valve cut angle sealing surface at all.
#49
C
cheny
C
cheny
Reading all this about replacing valves mine I found running premium gas stopped smoking was this done it didn't say anything about the gas
#50
T
TobyU
The problem is what's your definition of smoking?? What kind of smoke was it? Was it mostly white, mostly blue or mostly black and sooty?
There should be no way that putting premium fuel in your lawn mower or tractor should run just perfectly with no discernible smoke and then draining that fuel out and putting cheap 87 octane in or whatever your cheap low-grade fuel is in your area and running it for 5 or 10 minutes to make sure you're into 100% of that fuel....would in any way make it start to smoke at all.
I say this because that would be the only even somewhat scientific way to test it. No smoke batch out potential smoke batch in back to back.
I'm afraid that many of these personal experiences involve many days if not weeks and often they are accompanied by some other problem or repair that was recently done so it's not scientific or accurate to assume that one particular thing stopped or started another particular thing or symptom.
But as I always say, if you do this long enough you will eventually find something that you see with your own eyes that technically isn't possible.
T
TobyU
I'm going to file this in the category of things that can't happen and aren't possible until I actually see it for myself.Reading all this about replacing valves mine I found running premium gas stopped smoking was this done it didn't say anything about the gas
The problem is what's your definition of smoking?? What kind of smoke was it? Was it mostly white, mostly blue or mostly black and sooty?
There should be no way that putting premium fuel in your lawn mower or tractor should run just perfectly with no discernible smoke and then draining that fuel out and putting cheap 87 octane in or whatever your cheap low-grade fuel is in your area and running it for 5 or 10 minutes to make sure you're into 100% of that fuel....would in any way make it start to smoke at all.
I say this because that would be the only even somewhat scientific way to test it. No smoke batch out potential smoke batch in back to back.
I'm afraid that many of these personal experiences involve many days if not weeks and often they are accompanied by some other problem or repair that was recently done so it's not scientific or accurate to assume that one particular thing stopped or started another particular thing or symptom.
But as I always say, if you do this long enough you will eventually find something that you see with your own eyes that technically isn't possible.
#51
B
Bertrrr
B
Bertrrr
Replacing the head will not do anything for a smoking engine, sounds like the valve guides are leaking a bit, it's really not an issue for most people - unlikely the owner wants to throw more money at it if it's doing what you say
#52
B
Bertrrr
B
Bertrrr
Replacing the head will not do anything for a smoking engine, sounds like the valve guides are leaking a bit, it's really not an issue for most people - unlikely the owner wants to throw more money at it if it's doing what you say
#53
T
TobyU
But about the head replacement.. it probably is a leaking valve guide but the valve guides are in the head on this machine so a new head would solve the problem of the leaky valve guide. Lol
It's just the hard, annoying, expensive way of fixing it.
Pop that spring off and put a nice new umbrella stem seal on the intake or heck, do the exhaust too if you want, and make sure it has 30 weight oil in it and not full synthetic or some multigrade and call it fixed.
The owner was using something like
a half a quart or even more per hour so at this point it will feel like a new machine to him.
T
TobyU
I'm sure the owner would be quite happy at this point but he has some weird shop owner who wants it perfect and is going to put a lot more time and money into it or at least drive this tech nuts without even consulting the customer and seeing how happy is the situation currently which is what he should do.Replacing the head will not do anything for a smoking engine, sounds like the valve guides are leaking a bit, it's really not an issue for most people - unlikely the owner wants to throw more money at it if it's doing what you say
But about the head replacement.. it probably is a leaking valve guide but the valve guides are in the head on this machine so a new head would solve the problem of the leaky valve guide. Lol
It's just the hard, annoying, expensive way of fixing it.
Pop that spring off and put a nice new umbrella stem seal on the intake or heck, do the exhaust too if you want, and make sure it has 30 weight oil in it and not full synthetic or some multigrade and call it fixed.
The owner was using something like
a half a quart or even more per hour so at this point it will feel like a new machine to him.
#55
T
TobyU
It doesn't really use that much but it was for a while because the dipstick o-ring was leaking and the dipstick top hold down screw had been messed up and wasn't tight so it was wiggling and that caused it to puke a little bit of oil out of the breather tube into the air filter housing.
I ended up using the straight 40 and then I just stayed with it or maybe I put some straight 30 in a while back but it was definitely VR1.
I like that extra layer of zinc cushioning metal to metal contact just in case you know since these stupid little engines don't actually have babbit coated rod bearing inserts.
T
TobyU
I have a fairly High hour woods mow n machine that's really a grasshopper with an underpowered bridge vanguard 12 horsepower or maybe it's a 14 but I think it's a 12 with a 44 inch deck and they should have stuck with the 16 they did a lot of or even the 18th but I run straight 40 Valvoline vr1 racing all in that because of the extra high zinc content.That too, good old 30w, lets not worry about gas mileage!! Seals & oil!
It doesn't really use that much but it was for a while because the dipstick o-ring was leaking and the dipstick top hold down screw had been messed up and wasn't tight so it was wiggling and that caused it to puke a little bit of oil out of the breather tube into the air filter housing.
I ended up using the straight 40 and then I just stayed with it or maybe I put some straight 30 in a while back but it was definitely VR1.
I like that extra layer of zinc cushioning metal to metal contact just in case you know since these stupid little engines don't actually have babbit coated rod bearing inserts.
#56
sgkent
sgkent
just for what it is worth, if valve guides are worn on any engine, no valve job will seal properly because the valve will not stay centered in the seat. All one is doing is cleaning things up a bit.
That said, this horse has been pretty beat down. If the owner complain still about smoke then it is a classic promised more than could deliver. Dreaming of restoring a machine with lots of hours to what it was like when new is just not viable these days.
That said, this horse has been pretty beat down. If the owner complain still about smoke then it is a classic promised more than could deliver. Dreaming of restoring a machine with lots of hours to what it was like when new is just not viable these days.
#57
T
TobyU
The guy who owns the shop is insistent on it being perfect from what OP has posted and he's the one with unrealistic expectations.
I bet the owner would have been happy right after it was put together and it's current situation and would have an operable mower right now using almost no oil compared to what it was doing before but it seems they have been too far removed from the loop and that's a bad idea.
As you said, you don't want to promise more than you can deliver but you also don't need to to promise anything more than what makes them very happy!
You are correct about the valve job but you said seal properly. That's a pretty loaded word. Adequately, properly, correctly, perfectly can be all very different.
That gets back too my earlier comments about lawn mower engines being low performance little turds that are very forgiving.
These valves don't really have to seal all the way to properly for the engine to run quite well for many years. Lol
That's fortunate, because it seems most lawn mower valve jobs have been a single angle one forever, (there might have been a two angle about job but not common in a shop environment) whereas cars were getting a three angle valve job back in the 80s and maybe before that at every local speed shop and even your standard performance engine builders and machine shop head places.
I was told just a couple years ago from an old friend I ran into who used to do many of those built engines and did machine shop work for me back in the 80s and early 90s.
He said these new cars have like a six angle job or something equivalent to that and that doing the old three angle valve job we used to do to one of those valves today would be a severe downgrade to what comes from the factory.
Somehow, I don't think lawnmower engines have kept up.....
T
TobyU
At this point I don't think the owner has any idea what's going on other than the mower isn't fixed yet.just for what it is worth, if valve guides are worn on any engine, no valve job will seal properly because the valve will not stay centered in the seat. All one is doing is cleaning things up a bit.
That said, this horse has been pretty beat down. If the owner complain still about smoke then it is a classic promised more than could deliver. Dreaming of restoring a machine with lots of hours to what it was like when new is just not viable these days.
The guy who owns the shop is insistent on it being perfect from what OP has posted and he's the one with unrealistic expectations.
I bet the owner would have been happy right after it was put together and it's current situation and would have an operable mower right now using almost no oil compared to what it was doing before but it seems they have been too far removed from the loop and that's a bad idea.
As you said, you don't want to promise more than you can deliver but you also don't need to to promise anything more than what makes them very happy!
You are correct about the valve job but you said seal properly. That's a pretty loaded word. Adequately, properly, correctly, perfectly can be all very different.
That gets back too my earlier comments about lawn mower engines being low performance little turds that are very forgiving.
These valves don't really have to seal all the way to properly for the engine to run quite well for many years. Lol
That's fortunate, because it seems most lawn mower valve jobs have been a single angle one forever, (there might have been a two angle about job but not common in a shop environment) whereas cars were getting a three angle valve job back in the 80s and maybe before that at every local speed shop and even your standard performance engine builders and machine shop head places.
I was told just a couple years ago from an old friend I ran into who used to do many of those built engines and did machine shop work for me back in the 80s and early 90s.
He said these new cars have like a six angle job or something equivalent to that and that doing the old three angle valve job we used to do to one of those valves today would be a severe downgrade to what comes from the factory.
Somehow, I don't think lawnmower engines have kept up.....
#58
T
The Specialist
T
The Specialist
Within minutes, I can tell how good a mechanic is on these small engines of walking into a shop. Believe it or not, many shops don’t know what they are doing! I’ve done small engines for 35 years. I was in it from the old school of points and condensers and that 2 strokes always used reed valves. My instructor back then in college stated “ if you don’t know the secrets of the engine, you will never fix it” and he was right! The valves are the most important thing, but are always over looked. As you own a shop, the next time that you get a smoker engine or one that runs with a surge, take the valves out and have a look. I agree with you in using a wire brush on the cylinder head to clean them up, but the valves, I use emery cloth. I have not used valve lapping compound in over 25 years as I got that good at doing valves.Now you know you're going to make some people's heads spin around talking about cleaning up valves and even daring to mention touching the sealing surface with something so unprecise as your finger!!!
I don't actually think I've used Emery cloth on them or sandpaper but I have used the fairly fine wire brush on the grinding wheel to clean them up I do however, recommend using some course grit lapping compound and then some fine grit lapping compound and lap them decently in the head once you do this because you're probably going to round off the sharp angles a little bit even though cleaning up the crap and making the surface smooth probably outweighs any problems you could cause by getting the angles off a little but then when you go and lap them you will be increasing the sealing ability quite a bit.
When I officially opened my shop in 2011 I looked around and thought about buying one of the old school valve grinding apparatuses but found out they're still pretty expensive and I'm a cheapskate and there's not really that big of a demand or need to do it and I don't rebuild inches anyways and most of those jobs that would require that are simply too labor intensive and time involved for me to bother doing when I can sit here all day long doing annual services and carb cleanouts and make a lot more money in less time and help a lot more people overall.
So I gave up on the idea but if I'm ever at a garage sale somewhere and see one that they're basically giving away I will pick it up.
The only time in my life I ever actually used one was in junior high school in the metals and small engine class where are we did a complete rebuild and ground the valves whether they needed it or not.
The fact is, lawn mowers are low performance little turds!
This makes them very forgiving and you just don't see that many burnt valves or valves that really need to be ground.
You find far more popped valve seats and way more slipped valve guides causing valve train issues but it's not the actual valve cut angle sealing surface at all.
#59
T
TobyU
However, I think we can both agree that on a brand new perfectly manufactured valve and seat or a freshly ground valve and seat, you wouldn't be doing it any benefits by scratching on it or touching it with emery cloth or a wire brush or anything other than maybe a shop cloth.
But since we don't get many of these, anything that you can find that makes stuff work out better is a plus.
I would say most people don't use lapping compound because like I said in the earlier post the valves aren't that really big of an issue because the engines are so forgiving that good enough works out okay and that's what most of the valves do is seal up good enough.
After you clean them up with the emery cloth you would probably get an even better seal if you then lapped them but again, they're already plenty clean enough to seal up properly so it runs like it should and you've cleaned off the carbon deposits and stuff so they're sealing better then when you started.
I don't use lapping compound over two or three times a season in fact the kit I have now of the two small tubes is just about empty especially on my fine since I have used that multiple times to polish out some carburetor seats when I didn't have or couldn't get a replacement like on some of the Kawasakis that aren't removable or at least aren't available as a replacement.. that kit is just about empty and I purchased it in 2011 so I obviously don't do very many because those tubes are small.
Same size tubes as the small tubes of JB weld.
I certainly don't think you could harm an old already used valve and seat my by lapping it some but I don't think it is the cure-all or as necessary as some people make it out to be.
In the old days it was a requirement after the valves were ground and automotive heads but sometime in the mid to late '80s or some are very close to that the machines were much better and they stop doing that time consuming process because it just wasn't necessary also.
You will still hear old guys talk about how you have to do it and it's a must but I beg to differ....
Personal experience says otherwise just like you with using your finger and a piece of crocus cloth soaked in gasoline to clean up your valve surfaces.
Many would say that's a big No-No but your experience having great results doing it proves otherwise.
When it works...keep on doing it.
When it ain't broke......
T
TobyU
I'm sure it works fine for you and like I said, cleaning up deposits and other crap like that and the carbon buildup probably far outweighs any slight variation of the margin and the sealing surface from the angles being a little off or not quite as crisp .Within minutes, I can tell how good a mechanic is on these small engines of walking into a shop. Believe it or not, many shops don’t know what they are doing! I’ve done small engines for 35 years. I was in it from the old school of points and condensers and that 2 strokes always used reed valves. My instructor back then in college stated “ if you don’t know the secrets of the engine, you will never fix it” and he was right! The valves are the most important thing, but are always over looked. As you own a shop, the next time that you get a smoker engine or one that runs with a surge, take the valves out and have a look. I agree with you in using a wire brush on the cylinder head to clean them up, but the valves, I use emery cloth. I have not used valve lapping compound in over 25 years as I got that good at doing valves.
However, I think we can both agree that on a brand new perfectly manufactured valve and seat or a freshly ground valve and seat, you wouldn't be doing it any benefits by scratching on it or touching it with emery cloth or a wire brush or anything other than maybe a shop cloth.
But since we don't get many of these, anything that you can find that makes stuff work out better is a plus.
I would say most people don't use lapping compound because like I said in the earlier post the valves aren't that really big of an issue because the engines are so forgiving that good enough works out okay and that's what most of the valves do is seal up good enough.
After you clean them up with the emery cloth you would probably get an even better seal if you then lapped them but again, they're already plenty clean enough to seal up properly so it runs like it should and you've cleaned off the carbon deposits and stuff so they're sealing better then when you started.
I don't use lapping compound over two or three times a season in fact the kit I have now of the two small tubes is just about empty especially on my fine since I have used that multiple times to polish out some carburetor seats when I didn't have or couldn't get a replacement like on some of the Kawasakis that aren't removable or at least aren't available as a replacement.. that kit is just about empty and I purchased it in 2011 so I obviously don't do very many because those tubes are small.
Same size tubes as the small tubes of JB weld.
I certainly don't think you could harm an old already used valve and seat my by lapping it some but I don't think it is the cure-all or as necessary as some people make it out to be.
In the old days it was a requirement after the valves were ground and automotive heads but sometime in the mid to late '80s or some are very close to that the machines were much better and they stop doing that time consuming process because it just wasn't necessary also.
You will still hear old guys talk about how you have to do it and it's a must but I beg to differ....
Personal experience says otherwise just like you with using your finger and a piece of crocus cloth soaked in gasoline to clean up your valve surfaces.
Many would say that's a big No-No but your experience having great results doing it proves otherwise.
When it works...keep on doing it.
When it ain't broke......