Too much compression. adjusted the valves and it got worse

[mmoffitt]

From my observation and experience...First things first like the nice policeman says ""License and Registration" first... that Equates to """Make Model and serial number""" so these "Fine, Gentle people",I use the term "loosely"! Can do their best thir best to help you from the get go!!!
Thanks for everyones help in the past please all be well and safe out there!

 

[Johner]

I will guess that you set the valve lash at TDC on the exhaust stroke and not on the compression stroke.
A common mistake we all make every now & then
So from scratch rotate the engine and watch the valves move with the spark plug removed
The lower ( inlet valve) should close ( rocker goes loose ) just after BDC then stay like that all the way till just before TDC when it opens a very tiny amount to decompress
The engine should then fire so both valves will be closed ( both rockers loose ) all the way to BDC when the Exhaust valve ( top one ) should open and stay open all the way to TDC where the inlet opens and then the exhaust closes .
The inlet remains open all the way to BDC then closes and you are back to the beginning.

The other trick that confuses people is you adjust the valve lash with the big nut and use the torx grub screw to lock the big nut .
If you are new to this it is a good idea to adjust the valves then run the engine for a few minutes ( messy ) then let it cool down stone cold and check them again .
Do not worry if you have to do them 4, 5 or 6 timed till you get the feel of it .
As for You tube videos forget most of the menstural clots you have been looking at.
I would bet that they are paying some computer hackers in India a lot of money so their trash videos come up first in any google search.
Remember every time you look at one of them some makes a cent or two
The only 2 I recommend are Taryl Fixes All & Donny Boy 87
Skip the first 30 seconds of Taryls videos if you do not find school boy humour funny
It is a ploy to make him more money.
You tube requires a viewer to be there for 15 seconds and if you time the preview followed by the animated title page than comes on before they start providing any information you wil see they all go better than 15 sec
From then on in they get credit for each block of time you stay there , usually in 30 sec incriments
None of them are there for your benefit
The brain dead ego maniacs are there to increase their self esteem and all the rest are there to make money and solicit free goods .

Good info, knew they were there to make money, the timing of the skit I did not know, very informative and yes Taryl is very good.

 

[DHook]

I enjoy Taryl's videos but could do with less of the off-topic theatrics. Just the facts, mam. I've watched quite a few of them and am going to attempt a fluid change on a hydro-static tuff-torq transmission soon on a Husqvarna mower I bought for $25.

Re: the valve adjustment; do you do that on a warm or cold engine the first time? I know you should run it after the adjustment and check again but the first adjustment, warm or cold engine?

 

[Earthquake Landscaping]

First setting is overnight cold.

 

[Earthquake Landscaping]

Personally, as other posters have mentioned.... I agree! There's no such thing as too much compression!!

Let's look at that from a not too technical viewpoint....

"ACR" .. AKA.. Automatic Compression Release. Well, What does that actually do? AFAIK, the compression release is there so that you can just try to start a motor without having to make sure that you have tweaked the engine to a point where you will rotate it 270 degrees before it hits another compression stroke. Basically, if you start from TDC, on the combustion cycle, by the time that the engine gets to the next compression stroke, it should be rotating fast enough to overcome the compression, and continue rotating with enough R.P.M. to provide sufficient vacuum at the Carb, so as to properly atomize fuel for combustion. At that point, a "ACR", isn't necessary for starting.

That being said, I'm not going to debate that the ACR system needs to be correctly set, for optimal operating. That's just over my head.

Valve lash settings don't really have a significant effect on overall compression ratios. When you're turning an engine over by hand, or with a starter motor, there's plenty of time, when the valves are open, to allow sufficient air into the cylinder (s), to have air ( mixture) available to compress for combustion. The throttle should be wide open for a compression test. Too tight valve settings, would result in ... low compression ( leakage ), burnt valves, ( if it even ran), and is actually an unlikely scenario, ( unless improperly set). Loose valve settings would be noisy, and result in lowered power output, as the lift, overlap, and duration become less than optimal. Set tight ( as far as tolerances is concerned), is like having a high performance cam shaft. Set loose, ( at the high end of the spec), is like having a smogger cam..

"Hydrolock".. Hydro lock doesn't make it difficult to turn over an engine... it makes it pretty much impossible! Fuel, like other fluids ( water, oil, etc.) , are, for all practicable purposes, non- compressible. A Hydro locked engine wouldn't just be stiff to turn, it would be impossible to turn.
Also interesting was the observation by the OP, that, with the plug out, it was easier to turn.. Hmmmmm.. It shouldn't have just been easier to turn, it should have been almost effortless to turn over.. There should have been very little difference of the force needed to turn it over anywhere in the 4 strokes,, If turning it over without a plug in it wasn't easy - peasy just like butter.. then there's a reason to look further into the internal mechanics of the engine.

 

[woodstover]

I enjoy Taryl's videos but could do with less of the off-topic theatrics. Just the facts, mam. I've watched quite a few of them and am going to attempt a fluid change on a hydro-static tuff-torq transmission soon on a Husqvarna mower I bought for $25.

Re: the valve adjustment; do you do that on a warm or cold engine the first time? I know you should run it after the adjustment and check again but the first adjustment, warm or cold engine?

Always adjust valves on a cold engine.

 

[cleverlever]

17.5hp IC
model 31C707-0154-E1

I bought this engine used and used it 3 seasons now. last year it became hard to start. turning the motor by hand past the compression stroke was difficult and thats where it would hang up when I tried top start it.
of the 5 times I started it this season it would only start 2 times on the first try. If I put my battery charger on it I can get it to start. Battery is testing at 12.8 volts and is charging close to 16 when its running.

I went to adjust the valves today. There was more oil then I expected in the valve cover. Maybe 1/2 a cup. The valves were very tight. No gap at all at top dead center. I re-gapped them. guy on you-tube working on the same engine said 6 thousandths on the top and 10 thousandths on the bottom. That's what I did. When I put it back together it did not start, it hung up in the same place as before in the compression stroke.

The motor was even harder to turn then before. almost impossible to turn it by hand.

What do I need to look at next?

I had the same problem and fixed it by loosening the valve lash. Put a compression gauge in it and watched as I loosened the lash. Didn't have to add to much lash to get the compression up. Started really easy. I have had the worst problems with compression release on the Kawasaki's.

 

[Earthquake Landscaping]

"of the 5 times I started it this season it would only start 2 times on the first try. If I put my battery charger on it I can get it to start. Battery is testing at 12.8 volts and is charging close to 16 when its running."

Sometimes, the devil is in the details....

So.. It only started 2 times on the "first try".. Did it take 3 more tries to get it started, but it did start? That comment / observation isn't much information for clarity..

If having the miniscule amount of extra grunt from the battery charger being connected when starting makes a difference.. then the battery is suspect. Realistically, a battery is designed to put out a maximum output for starting, and then slowly re-charge from the electrical system. A 30 amp hour battery takes 3 hours to recharge from flat with a 10 amp hour charge. What little the battery charger puts out, compared to the electrical demands of the starter motor's use is almost negligible. The only exception would be a charger with a booster function.

Voltage is a "thing" for batteries... so, however, is cranking amps. More specifically, CCA ( Cold Cranking Amps).. These are the amps that spin the engine. Sim[ply having enough voltage, doesn't necessarily spin the engine hard enough to start. IMHO, 350 cranking amps is a minimum, especially in cold weather.

Either load test the battery, or try starting it with jumper cables and a fully charged automotive battery, to eliminate the battery's lack of cranking amps as the root cause of the problem. If it stats with a jump.. look at a new battery. Just because it shows voltage isn't necessarily meaning that it has the necessary amps.

12.8 volts ( resting charge) .. is actually a bit high .. I usually see 12.6 .. to 12.7.. And, 14.6 on charge... I've never seen 16 volts as a charging voltage. To me, that would indicate a battery issue. Once started, the charging system should quickly replenish the drain in the battery from starting, and return to th e 12.6 to 13.0 volt range, as the battery approaches full charge.

 

[Chrisgixer2]

Suggest either

hydro locking ( pull the plug as said, turn it over, re fit plug try again. But you know all that )

or oil too thick. Is it worse when cold ?

 

[TobyU]

I am pretty sure I understand how to adjust the valves. I am good with that.

So after watching a couple videos, I am wondering if the compression release and cam shaft are not working properly.
when starting the engine it gets caught up on the compression stroke. I need to double check, but I think the bottom valve does not move like the top valve.
The engine is almost 20 years old and I got it used.

Could I have a cam shaft/ compression release issue? How would I know for sure?

It's very possible because the ACR on these Briggs & Stratton engines is an absolute joke! They should have fixed the problem long ago but Briggs basically refuses to fix anything of their inferior quality designs.
Don't get me wrong, I love Briggs & Stratton engines, some of them. I just call out what is crap.

I don't know why people want to insist on applying normal valve train and car valve train to these engines.
Don't do it!
Don't do the set one valve while the other valve is closed and all that crap.
It's not a car!
It's a low performance little turd mower engine so do it the way the manufacturer designed it to be set and designed it to work.

It is very simple.
Turn the engine over by hand until you get to top dead center on the compression stroke and then turn it until the Piston goes down at least one half inch past top dead center.
Now in reality, like I've told people for years, you can go a lot further than that and you can actually go all the way until almost bottom dead center until the exhaust valve starts to open so you have a lot of leeway there but the point is you need to get past top dead center!
So get the Piston pass top dead center and down an inch or an inch and a half and you're good to go setting both valves.

Now, I also don't know why people get into setting them at different than Factory spec clearances or making them more loose like they're giving some extra margin of safety.

I understand that unexhaust valves or any valve that could burn which is typically an exhaust valve, being closed longer is better so in this case more clearance is better but that's just not necessary!!

Set the darn things to watch the book calls for!

They already give you .002 a variance from Titus to loosest for each clearance so if you feel the need to go to the high side that's fine but don't go .008. when the spec is 005-007.
I know in reality it's not that big of a deal but come on people...
On the intake you should go on the tight side to get as much out of the ACR as you can.

The reason you don't have to go any larger even on the exhaust is because these things do not wear tight like a car or like many other engines.
You would think they would as the valve margin on the seat erodes and the valve stem tip effectively gets longer but that's just not how these work.
What happens 10.5 times out of 10 is the rocker arm tip and the valve stem cap and probably the push rod tip also or at least the rocker arm pocket it sits in wear away a little bit of metal so the clearance gets greater which means looser.
EVERY time you pull one of these engines apart that's been together for a while you will find these clearances at .010 to .016 etc.

Now that I'm off my soapbox.. the way to see if your ACR on the camshaft is busted is to adjust the intake valve correctly or just set it to zero lash where it's touching for test purposes and then turn the engine over by hand or spin it with the starter.
You will see the intake valve open and then close and immediately after it closes it will bump open for just a split second.
We call it the bump.

If it doesn't noticeably bump open slightly then your ACR is busted.

There is a workaround for this though and that's to take your air filter off and turn the engine backwards counterclockwise with your hands until it gets to the hard spot again. Then hold your hand over the air filter intake so you block off all the air. You should probably also have the choke closed when you do this...
This will make the engine easier to spin over because it won't have as much air inside of it to compress so it won't be compressing so hard.
I have been able to get everyone of these to start just fine this way and then of course they will mow fine it's just starting them that's hard.

It's not ideal because you do have a couple of little pieces of metal in a spring laying there and your base plate but oh well.

I replaced the number of these and I started out using all Briggs & Stratton brand parts and then I migrated over to the off-brands on eBay and Amazon and did three or four of them without any problems.
But then, last year I had major problems with one that failed in just a couple of months with only five or six mows.
It didn't fail the way the ACR fails but the cheap metal press on lobes and the splines on the shaft just stripped off and it got out of camshaft timing for the valves.

This made me afraid to use any more of them and if you read the reviews they are absolutely horrendous..
So I replaced it with a Briggs & Stratton with the new upgraded part number and so far it's been fine.