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Hi All,
I have removed the engine from my MTD Yardman mower to check the piston rings as I noticed a large "blow back" pressure ( my own term ) when I remove the oil dipstick when in use last summer. I also checked the compression when cold and remember it reading 55psi and 90 ish when warm. I need to remove the main pulley which is on the crankshaft. I don't want to try a standard wheel pullers as the 2 pulley wheels look as if they could be damaged if I put them under pressure with the pullers. I am considering welding a large nut to the bottom of the pulley and screwing a large bolt up into the pulley shaft which should pull the pulley off the main shaft.
Yardman model 136C561C643
Engine Briggs and Stratton 11.5hp IC engine.
Yardman machines are rare here in Ireland so I cannot ask any questions locally. It has proven to be a good little piece of kit for over the past 20 years and will keep it running as long as I can.
Any hints or advise appreciated.

Heat and penetrating oil will be your friends. Since the engine is off the mower, which is lucky since most don't come off with the pulley attached. You can also hang the engine from the pulley and let gravity assist you in removal. Just make sure to have something that the engine can land on if the pulley slides off.

If you can get something between the sump and the pulley that bears against the boss and not the edge of the pulley like some tyre irons or wrecking bars.
Flip the engine upside down and put a cap screw into the end of the crankshaft to protect it.
Then with an air hammer lay into the end of the cap screw.
With the weight of the engine plus the 1,000 little whacks a minute it will usually shock the pulley off. very slowly .
A bit of heat will not hurs as will some of your favourite penetrant poured down the key slot.
Some I have done here have taken the best part of a full day to do but they all come off in the end.
The important thing is to only press on the boss part of the pulley and of the flange part of the pulley.

With bert on the air hammer. I have crank bolts i have drilled a 1/4" wide by 1/4" deep divots in to use with the air hammer. You won't be able to hold the point of the air hammer bit on the flat head of the bolt. If you try it drill a divot in the head of the bolt.

I setup a flat piece of cast iron ( not ideal material ) with a slot cut out of it that fitted snugly around the main shaft . I welded two vertical pillars on the flat cast iron that I placed into the cross arm of a hydraulic pullers. Putting pressure on the pullers lifted the iron plate up against the pulley tube but alas the 3/8'' cast iron plate snapped in half. No sign of any movement at all. I may have to take to machine shop and see if they can remove it.

UPDATE.,
I had to make an attachment to fit tight to the crankshaft and put pressure against the pulley shoulder using an hydraulic pullers. Severe pressure was required to remove the pulley. I now have the piston and rings removed and I am going to order a new set of rings, wheather the originals are worn or not. Everything looks very clean inside the crank case and the piston appears to have no side movement when in the barrel. Theres no sign of scoring or wear in the cylinder barrel . Does anyone know if I insert one of the rings into the cylinder what gap should I expect between the ring ends. I know I would probably need a new ring to insert first and make comparsons. Also, when putting all back together again what type of gasket do you suggest for the crank case.
See pulley removal setup.

Congratulations .
Buy the gasket rebuild kit most will have multiple sump gaskets which are used to set the end float on the crank .
Measure the depth that the sump oil seal is set to and write it down as too deep will cause oil flow problems
When you replace the pulley use liberal amounts of nickel anti sieze on the shaft ,'
Fill the key way, push the pulley back up then push some more up the key way and next time it will drop off into your hands.
All bar one of these I have done had the belt keepers bent back because the owners could not pull the pulley down far enough to replace the drive belt.
To give you ring gaps we will need the full engine numbers that are stamped into the rocker cover

Thanks B,
I ordered a piston and rings and a cylinder head gasket this afternoon. I reckon that as I have the engine removed and stripped, the extra cost for a piston is well worth it. I intend using a chemical gasket on the sump casing. I cleaned the crank shaft that held the pulley with some fine paper and oil and it now pops on by hand. One thing I noted before I removed the cam gear is when both timing marks are aligned ie, crank shaft and cam gear, the piston is not TDC. Just an observation. I now have to sit and wait for the spares to arrive.
Will keep all updated.

Silicon on the sump is a no no no .
IT will clamp the crankshaft too tightly.
Note there is no thrust washer or bearing on the bottom of the crank, it just sits there on the sump.
Some rebuild kits have 3 gaskets of different thicknesses while other will have 3 thin ones to be sacked .

Thanks for that. I will see if I can get one. If I realized this earlier I would have ordered one when I placed order for the piston.

I see 3 listed of different thicknesses . Whats the procedure in selecting and fitting. I take it that its got to do with crank end play ?????. The one that is .015 is listed as standard. My engine is year 95 ( code 951215ZB ). Maybe I can make one with .015 paper.

I am not a fan of silicon anywhere on an engine.
Takes longer to apply properly and 100 times longer to remove than a real gasket
Axle grease on the crankcase side and your favourite joining compound ( I use Hylomar blue ) on the sump side.
Thus the gasket will always strip off clean.
Same story for the rocker cover .

Yes it is all about end play which should be just perceptable.
I can not give you a number without the engine numbers requested previously.
THe alloy will expand more than the crank shaft so the running clearance will open up once the engine is hot .
Some are full pressure feed , some have pressure feed just to the big end .

My engine is old type splash feed. No oil pump.

BTW,
As I await the parts delivery I am wondering if it is a good idea to check the valves and maybe re-seat them.
Any idea about the valve clearance settings on this machine as it is fixed.

Got to this thread and download the manual
The valves are set by grinding the seats to close the gap or grinding the end of the valves to close them up.
L heads tend to close & OHV ones tend to open
We really need those engine numbers to prevent you getting duff information
other post

Hi,
That makes sense. Never thought about how to adjust the valve clearance in my engine setup. My full engine details are28D707 type 0123-01 code 951215ZB ( or Z8 ).
Did you post the link to the manual.
Thanks again.

Not guilty on the manual charge your honour
I don't use any cloud basd anything if I can avoid it
The manual gives numbers for both springs fitted & spring not fitted.
I have never had any luck using the spring not fitted clerances.
Ane when I said grin the stem I really meant touch up with a diamond or oil stone

HS5424, click on the "other post" link in post #16 and you will the manual link I post in that thread.

I know I guilty of that charge, Bert but if you want to serve my time I let you.

The manual I posted is directly from Briggs Power Portal that I maintain on my Google drive for my forum members of the forum that I administrate. Many of those members do not have access the Power Portal. I do have few of the latest manuals, APSI, SB, and DSB that I haven't posted to my public section but they stored in private directory on the drive. I also use One Drive for temporary manual posts. Those I usually only make available for a couple days then I delete them. Both of these drives are backups on my in house system most important files.

On the valve stems I usually file them squarely but I have also have a fine grind stone on my grinder that can grind and polish the stems. Go from zero to .011 can take time with the last couple thousandths being sneak up on.

Thanks StarTech
I will take a look now.
I think the manual in post # 16 is for a different type engine. I stand corrected ??????.

UPDATE.
I sent an email to Briggs and Stratton via their website and to my surprise I got a response in about 2 hours with the valve clearance measurements for my engine.

I dd not download what Star Tech linked to
You should have an L head ( side valve engine ) and briggs made one manual to cover them all from push mowers to ride ons and stationary engines as well.
Star Tech may not have included the entire manual in the link.
If you troll around the web it is all over the place but you need to look for L head .
Techs that work for accredited dealers or are themselves accredited have access to a lot of stuff that the great unwashed and freelance techs such as myself are not allowed to look at lest we all turn to salt ( stone if you are of a different faith ).
hard to believe but Australia has the worst internet & the most expensive internet on the planet thanks to a decision decades ago that competition in the telephone market would be a good thing ( it wasn't ) .
Thus uploading files to the forum costs me money as does downloading and with the Covid-19 isolation happening even a big email will time out .

Thanks bertsmobile1,
I didn't know that the side valve engines were referred to as L head. I think I have all the information I need now that B&S sent me the valve clearance measurements. I am going to check the valve clearance and re seat them while I await the new piston and rings to arrive. I will keep you all posted on my progress. The grass is starting to grow now here in Ireland so I hope the parts arrive pretty soon. Internet in Ireland was pretty much the same as with you down under. For years there was only one state owned company supplying telecoms service in the entire country. I recent years other telecom companies were allowed to operate here and we all thought " great, competition in the market". The only problem was that all companies had to use the same run down infrastructure which delivered 1Mb if you were lucky. Fiber now being rolled out here but again the big telecom operators are not interested in the rural areas, only the cities and large towns where the number are. Follow the money trail.

Yep.
I am on a from.
The fiber cable runs right past my front door I watched them lay it but I can not connect to it nor can the other 30 properties on the hill or the 120 along the river.
We are being forced to use satelite . That was supposed to be for remote regions & I am 70 km from the Sydney GPO not exactly remote.
However the shinny suits are on BIG bonuses if they get the jb "finished" by July 1 2020 so every one who looked like they would not make the deadline got shot onto Skymuster which is so overloaded it can not not cope .
Then the morons had the ordasity to blame Netflicks for the problems because they upped the frame rate on their video streaming which apparently overloaded the "future proof" system .
Evn worse I have to pay for a 10 Gb connection and am yet to see 1 Gb

I feel ya. All i can get is DSL and i can see the Spectrum cable from my house on a cross road. They say there is not enough people on my road to be profitable.
I have been toying with the idea to try and do a wireless link between my house and my church that is 2.5 miles away with business class high speed internet.

They are having exactly that problem right now.
People with fiber to the door are buying the top speed unlimited package then setting them selves up as a microwave node for a dozen or so friends.
If you get the right gear for the closed bridge and then run a virtual server on your machine it is hard for the telco to work out if you just have a lot of computers at home or are running a network.
To do this they have to actually track all of the sites that everyone visits then look at what is cashed on each & every computer which is against the privacy laws .

Now if a teco was thinking they would see this as the people demmanding a better service not as a user pirating their service .
The workshop here had a microwave link to the new house 1/2 mile away because the telco wanted $ 20,000 to hook the new house up with 5 poles from a side street .
Been like that for better than 10 years till a new tower went up so he went mobile web which while being more expensive per Kb it got rid of the land line rental .
I am trialing t right now and if I can migrate the 22 email addresses will do the same thing

Lately i have been doing a lot of setting farmers up with internet to their out buildings and barns. Wireless IP cameras are very popular with the low prices. I have been asked but i don't want to get involved with with people sharing their internet. Don't need my name mentioned if someone starts asking questions. I can do the church since i admin all the computers and the network. I am the IT guy for a few small companies but trying to get away from it. Just tired of trying to keep up on all the tech and Micro$uck BS. Money is good but too time consuming. Rather have a wrench in my hand than a mouse.

Use Ubiquiti gear .
I have 12 friends working of mine at a distances up to 7 miles.

That is what i use. I have a bunch of Loco M5 and M2 bridges at customer sites with flying saucer access points. I have some Unifi networks with customers too. Great stuff for the money. If you are point to multipoint setup what device are you using at your location?

I have a rocket M5 plugged into a 120 degree panel. Customers local to me ( up to 1 mile ) use nano stations and ones further away use power beams. My rocket went faulty recently after 6 years.

hs5424 said:

I have a rocket M5 plugged into a 120 degree panel. Customers local to me ( up to 1 mile ) use nano stations and ones further away use power beams. My rocket went faulty recently after 6 years.

Dropbox - File Deleted - Simplify your life

www.dropbox.com

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Da'yum that's a serious tower!

This is how we did it in the old days.

hs5424 said:

This is how we did it in the old days.

Dropbox

www.dropbox.com

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You got bigger ones than me my friend.

UPDATE.
Received the piston / rings today and fitted them. Fitted new head gasket, torqued head, seated valves and checked clearance, made crankcase gasket as I didn't order one originally but I made with gasket paper which is the same thickness as the heavy one that is supplied in the kit for this engine. Torqued the crankcase also. I fitted the engine back into the yardman mower and it fired up on the first turn of the key. One thing I noticed is that if I remove the oil filler plug while running the rev's will drop. Is this normal or do I still have a problem with the engine. I am not a mechanic so I don't know if this is normal.

Final observation,
Checked the compression cold today to compare readings since I replaced piston and rings etc and measured 70psi now. Wondering if this is ok.

Because of the decompression mechanism cranking cylinder pressures are meaningless which is why we use leak down tests to check cylinders & valves.
New rings in an old bore take a while to bed in particularly if it has not been honed before the rings were fitted.

Thanks,
I don't have any experience lawnmower engines etc as this was my first attempt at lawnmower engine restoration since I rebuilt an old BSA motorcycle engine about 30 years ago.
I borrowed a honing tool and took the glaze of the bore also. I was just wondering about the increase in compression I measured. I might check it when the engine is hot, just as a learning process. It starts first crank so I am happy with the outcome, so far.

If it is any consolidation I am currently re ringing A kawasaki FR 691V
Mr K says 64 psi to 98 psi for the engine at cranking speed.
Because of the ACR he actual time the valve is open to decompress will be inversely proportional to the actual valve lash
Rule of thumb is you need 70 psi for an engine to start, a bit more for blue smokes.
And congratulations for getting it back together
Picked up another basket case today cause the owner decided he was in over his depth

Best of luck with the Jap engine.

One thing that puzzles me on my engine is the choke setup. My mower has a manual choke but also has a choke link on the governor bracket . My understanding is that at full throttle this choke link applies the choke slightly for some reason. However there is a screw inserted in one of the holes on the control bracket which stops the choke leaver being pushed forward. Why as the choke link installed at all in the first place. ????????????.

hs5424 said:

One thing that puzzles me on my engine is the choke setup. My mower has a manual choke but also has a choke link on the governor bracket . My understanding is that at full throttle this choke link applies the choke slightly for some reason. However there is a screw inserted in one of the holes on the control bracket which stops the choke leaver being pushed forward. Why as the choke link installed at all in the first place. ????????????.

Click to expand...

Because at some time the engine has been replaced .
The choke comes on after the throttle has been opened fully for starting the engine.
Briggs call this set up "choke-o-matic" .
Once started you move the throttle back to close the choke /
It should have been removed when the manual choke was connected.

I own the machine from new. Took it out of the box myself about 1996.
I guess yardman fitted the engine to their mower and fitted the manual choke and put the small screw in place to stop the auto choke facility that came already fitted to the engine. Easier to put the stopper screw in place than remove the auto choke linkage. I am going to take a look for some carburetor repair kits as I think it's leaking some fuel into the block while its sitting idle.

UPDATE,
Fitted new float and float needle but still flooding when not running. Everything looks clean inside carb.

Get one of these, and shut it off when the mower sits.

But did you clean the seat ?

Thanks guys,
I am pretty sure that I cleaned all jets etc recently, however I will remove the carb later today and use my inspection scope to take a close up inspection. If all looks ok I will put a shut off tap on it as suggested by Fish. I was thinking about doing this but wondering how do I remember to shut it off when the mower is not in use. Maybe a 12v solenoid shut off would be an option.
I will post the outcome.

Flip the carb upside down
the weight of the float should hold the needle down hard enough so you can not blow through the intake .

Would have tried that earlier. I polished the seat where the needle rests and inspected it under the microscope and all looks good, however one thing on the carb is not original and that it the O ring on the bowl. I was thinking that if the non original O ring was a thicker gauge ( which I am almost certain it is ) then this could have an effect on the volume of gas in the bowl etc. I was expecting the correct one to arrive with the needle and float last week but it is on back order. I am going to do nothing until I receive and fit it. It will be interesting to see if it has any effect on the problem.
Watch this space.

hs5424 said:

UPDATE.,
I had to make an attachment to fit tight to the crankshaft and put pressure against the pulley shoulder using an hydraulic pullers. Severe pressure was required to remove the pulley. I now have the piston and rings removed and I am going to order a new set of rings, wheather the originals are worn or not. Everything looks very clean inside the crank case and the piston appears to have no side movement when in the barrel. Theres no sign of scoring or wear in the cylinder barrel . Does anyone know if I insert one of the rings into the cylinder what gap should I expect between the ring ends. I know I would probably need a new ring to insert first and make comparsons. Also, when putting all back together again what type of gasket do you suggest for the crank case.
See pulley removal setup.

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www.dropbox.com

Click to expand...

bertsmobile1 said:

Congratulations .
Buy the gasket rebuild kit most will have multiple sump gaskets which are used to set the end float on the crank .
Measure the depth that the sump oil seal is set to and write it down as too deep will cause oil flow problems
When you replace the pulley use liberal amounts of nickel anti sieze on the shaft ,'
Fill the key way, push the pulley back up then push some more up the key way and next time it will drop off into your hands.
All bar one of these I have done had the belt keepers bent back because the owners could not pull the pulley down far enough to replace the drive belt.
To give you ring gaps we will need the full engine numbers that are stamped into the rocker cover

Click to expand...

bertsmobile1 said:

If you can get something between the sump and the pulley that bears against the boss and not the edge of the pulley like some tyre irons or wrecking bars.
Flip the engine upside down and put a cap screw into the end of the crankshaft to protect it.
Then with an air hammer lay into the end of the cap screw.
With the weight of the engine plus the 1,000 little whacks a minute it will usually shock the pulley off. very slowly .
A bit of heat will not hurs as will some of your favourite penetrant poured down the key slot.
Some I have done here have taken the best part of a full day to do but they all come off in the end.
The important thing is to only press on the boss part of the pulley and of the flange part of the pulley.

Click to expand...

I just went through the same problem. Pry bar above the pulley while using impact hammer on side of pulley boss. Do yourself a favor and use anti seize on crank where pulley mounts. Will make it much easier next time.

I gave the shaft a good clean with very fine paper and applied plenty of grease when re-installing the pulleys. Hope you can see what I had to make up to get the pulley removed. I would guess that a few tons of pressure was applied in order to get it to let go. Copy and paste this link to see my pulley removal tool https://www.dropbox.com/s/24j4aru0s0fx0x2/20200328_113756.jpg?dl=0
By the way, my carb is still allowing fuel to get into the block when not in use. I fitted the new O ring on the carb bowl today and still the problem is there. To recap I fitted new float, needle, bowl O ring and polished seat. I think I will follow the advise posted by fish and fit a tap on the gas line and maybe order a cheap Chinese carb after the cutting season. I see from the packaging of the spares I received that they are ''genuine Briggs and Stratton'' spare parts made in China.

Success at last.
Cured carb flooding. Now before I explain what I did, I realize that the needle seat was the only component that I did not change to fix the flooding because (a), I would need to order one which would take a few weeks to receive and (b), there is a very slight possibility that after the wait the problem could still exist. I wanted to prove the seat was the problem before I ordered one. When I used the microscope to examine the seat I noticed that although it was spotless from the polishing I had carried out on it previously its orifice looked rounded at its edges. Maybe this is how it should be but I thought it should be the same shape as the rubber on the top of the needle in order for both seat and needle to have max surface area contact and provide a good seal. Here is what I did.
I got a 1.5mm drill bit and under the microscope I placed it along side the carb needle and compared the shape of the needle rubber with the drill bit cutting edge. The needle rubber is much more pointed than the drill bit so I gave the drill bit a quick dressing on the grinding stone so that its cutting face matched the angle of the rubber on the needle. I then used my dremel tool at slow speed and ran it in the seat orifice for about 1 second with very little pressure. Now the seat has a'' beveled'' edge to its orifice. I tested the carb outside the engine with a clear fuel line, marked the fuel level in the line and after 1 hour it remained at the same level. Before my mod I observed the fuel level dropping about 1'' in 15 mins or so until fuel would appear out the front of the carb. My description may seem long winded but in fact it took me less that 5 minutes to complete. Worth considering if you don't have a spare seat and you need to get up and running quickly. Probably quicker than replacing the seat.
N.B.
My microscope isn't a microscope at all . I use a lens in reverse from an old video projector.
Hope this helps others.