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Need Help with 7112H Kohler engine burning oil smoking


jsarro

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I recently brought this 7112H back from the dead with the original Kohler K301S engine.

It has not been running for at least 3.5 years. This is the first I have ever run this engine since getting the tractor 3.5 yrs. ago. I was told by a previous owner that it burned some oil.

First I had to rewire the ignition plug harness etc. The electrical was a mess.

I put a new carburetor on it, new plug, new gas line, gas filter, shut off, and reset and cleaned points.

I was able to get it running jumping it off a running car, and spraying starer fluid into the carb. It starts on the hard side, once I get it running, it will run for days, but within minutes it will be begin to burn some oil and smoke moderately. There is oil coming out from around a head bolt ( see picture) which is creating smoke as it burns off the heat shield, and some smoke coming out of the breather behind the carb.

I have not changed the oil or cleaned the breather.

The engine seems to run strong at idle and when given the throttle.

How do I diagnose this engine?

How do I proceed?

I'd like to fix the burning oil issue, but I am not sure how far I want to go with this time or money wise as I may not keep the tractor long term.

Thank You for the help.

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Does this mean a I need a new head gasket, rings, or worse?

Can the repairs be done without pulling the engine on this Kohler K series.

Thanks

 

 

Edited by jsarro
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I cant speak for the electric lift.  Compare part numbers and drawings from the parts diagrams to see if they are the same or close and then decide if you want to pull the parts to give it a try.

Lots of things can cause burning oil.  If the oil has become contaminated with fuel it will be thin and suck up the crank case tube easily and burn.  If the valve timing is off it can cause oil to suck up through the valve seat into the cylinder.  Of course worn rings or cylinder can cause compression loss and allow oil to be sucked straight past the rings into the cylinder.

Easiest thing to check is the oil to see if it is too thin and smells like fuel.  Next easiest is checking the valves.  I have not done this myself but need to look into it for a Kohler 341 that has suddenly developed starting issues.  Has spark, has fuel and air but only occasionally stutters never fully fires.  Went from running to not starting while being used last winter.

Oh yes, these Kohlers are known to burn oil if the crankcase breather gets clogged up and cant breathe properly causing oil to get sucked through and the inside of the engine gets closer to vacuum than it should.

These engines have a compression dump valve that lets the engine turn over easier until it reaches a good speed for spark.  That makes it unreliable trying to get a compression reading from them.  You would have to use a leak down tester to check for loss of compression in the cylinder.  My experience is only with my K341 and it has always taken a lot of power to turn over which makes me wonder if the dump valve is not working causing extra pressure from cylinder compression while turning over.  It may just be that these take a lot of power to spin regardless.

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Thank you niteowl.

So I should do the following:

Clean the breather

Adjust valves, I believe that is done behind the breather correct?

Inspect the oil and possibly change that for starters.

The tractor does seem to start hard but once running seems strong as an ox on the throttle.

Any other tips or things to consider?

Can rings and head gasket be changed without an engine pull, and how do I diagnose if this is needed?

Thanks for the help.

 

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I would think a leaking head gasket would make it less likely to pull oil into the cylinder as there would be less suction.

These engines have adjustable valves so that is a good place to start.  It is behind the breather plate.  There is a youtube video on adjusting kohler k series engines, that would be a good place to start.

You will want to check the valve guides for wear as that is one way oil gets into the cylinder.  Check that the valves are seating properly.  Re-seating the valves is very easy to do if the valves are not overly worn.  Just follow the procedures for checking and adjusting the valves from the manual or at least checking for excessive wear to determine if new parts are going to be needed and if the cost is worthwhile.

You would need to pull the engine to replace the rings as you have to remove the oil pan and disconnect the piston from the crank in order to remove the piston and replace the rings.  You would not want to do that until you checked the cylinder for wear or any scoring on the cylinder wall.  You can do that just by pulling the head.  Measuring the cylinder takes a bit of practice and requires the proper tools.  If you pull the head take a look at the top of the piston and see if it has numbers on it.  If the engine has been rebuit the piston will be stamped with the size over original bore of .010, .020, or .030.  I do not know how far over the original bore these can be re-done but most I have seen max at .030 over.
I am not expert on engines and have only done some minor internal work but have read up on it a lot.  There are too many things that might be the cause to give full descriptions until you have done the checks for the most common causes but checking and adjusting valve clearance is a regular maintenance thing so you should learn to do it and see how things look.

As for fuel in the oil, that can be caused by a number of things such as a worn cylinder\rings allowing fuel in the chamber to push past the rings into the oil, a sticking float needle causing the carb to backflow fuel that can get sucked through the breather and so on.   I have had this issue occur on a couple of tractors and in both cases it was a problem with the carb and not worn rings.  When the fuel contaminates the oil the oil can get foamy and turn a gray color.  It gets very thin and easily gets sucked back through the breather as a spray while the engine is running then sucked into the carb with the fuel causing smoke as it burns and eventually the engine not running due to diluted fuel or fouled plug.

The best way to test the cylinder for cylinder for leaks is with a leak down tester.  I think I need to give up and buy one because they come in handy.

Your oil is an unknown since you just got the tractor and you should change it anyway but first check the other things you can because if you have to pull the engine to work on it you will  be draining the engine and will have to drain the oil anyway.  Also make sure the air filter is not clogged as it can be a contributor to the problem as well.

 

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Pulling the engine on these is not as hard as you might think.  There are only a few wire connections, four bolts to the frame, two bolts to the driveshaft, fuel line, throttle, choke.  A few other miscellaneous items depending on how your PTO is setup, etc.  Very easy to just unbolt the front end to make it easy access to everything and getting the engine in and out.

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Trent thank you for all the great insight and guidance.

I will clean the breather, check the valve guides, adjust the valves, pull the head, check the piston and cylinder, and change the oil.

I will report back to what I find. I will probably not get to it until this weekend.

This exactly the kind of direction i was looking for and is much appreciated.

Thanks Again, what a great club! dOd

 

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You are welcome.
Hope it all works out.  I am still trying to determine why my Kohler stopped running but I have done a lot of reading up on them in the meanwhile.
I suspect mine could be valve timing or even a sheared flywheel key throwing timing of the spark off since it definitely has spark and has fuel.

One word of caution on these engines is be very careful about the oil level in the pan.  My oil level was only a little low but I was mowing on a steep slope when the engine started blowing white smoke and making terrible sounds.  The oil moved far enough back in the pan on the slope that it was not slinging any up onto the crank.

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Trent thanks for the heads up. dOd

I hope you figure out your engine issue also.

I hope to have some time to work on my Kohler engine this weekend.

I guess these K series don't have oil pumps either.

Do you think because my engine runs strong at idle and on the throttle that it is not likely that I would need a total rebuild with cylinder work and piston/rings in order to fix the smoking issue?

Thanks

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If it runs strong it probably does not need a rebuild yet.  The smoke could easily be from oil getting into the head from the valves or other ways I mentioned previously.  It's a matter of tracking down the source and then diving into the next step determining why type of repair it requires.  No matter what the issue is, checking and adjusting the valves is regular maintenance anyway and much easier on these as I believe they have adjusters and do not need to be pulled and ground down.  Maybe I will get a chance to look at mine this weekend as well but it looks like rain all weekend here on the east coast.

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Thanks Trent I got mine apart right now I will post some images for discussion soon.

For now here is the video on adjusting the valves:

 

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This is how I determined top dead center TDC.

I rotated the engine until the piston was at the top of the cylinder and the upside down T was visible through the timing sight hole in the housing.

This is what the everything looks like at TDC.

This should be at the top of the compression stroke.

Is this correct?

Thanks

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Here are pictures of the underside of the head, underneath valve cover, and the breather plate and filter.

When I first took off the breather, there was quite a bit of oil in the valve box and the filter is pretty saturated as well.

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I think based on my measurements the valve to tappet clearance is way off.

I put the engine to TDC as described above, and I can not fit a feeler gauge in between neither the intake or exhaust valve and tappet.

If I rotate the engine a full revolution with the piston at the top, but no visible T through the timing hole, I can then put the feeler gauges in close to spec. which is .009 for the intake and .018 for the exhaust.

I don't know if I am doing something wrong with determining TDC or if someone else set the valve clearance with the engine in the wrong position.

May this explain all the oil burning issues and tough starting?

 

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The inside of the cylinder has no gouges, no roughness,  and is completely smooth and slick.

The valves have carbon build up and the intake is definitely not seating well.

I am thinking the following so far:

Clean the piston.

Clean, reseat, and or replace the valves.

Reset adjust the valve tappet clearance.

New head gasket.

New breather gasket and filter.

Any advice on which course of actions to take would be appreciated.

Thanks

 

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So the T might be for timing, but probably doesn't denote TDC.  Its probably for a timing light, and it will be advanced from TDC about 15 degrees (I think).  If the timing is correct, the timing light should flash, and illuminate the T as it passed through the viewing window, similar to setting timing on an automobile engine.  The spark plug actually needs to fire before max compression, so the flame front has time to propagate through the mixture...

Setting TDC means using a dial indicator to measure the piston's travel as you rotate the crank around.  When the dial stops moving, you're at top dead center.   With the head off, you can set your lash easily by rotating the engine to near TDC, and then making sure the valves are both seated.  That is where you measure your clearance...and it sounds as though you're valve lash is correct, based on the measurements you got when you were able to slide the feeler gages through.  

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It looks to me like the valve clearance is off so the valves are not closing all the way at the appropriate time causing pressure to blow back into the crankcase and blowing oil out the breather.  It can also blow oil past the valve guides which is then sucked into the cylinder head and burned causing all the carbon build up you have.

I am NO expert on engines, I just know the basics plus a lot of reading but not so much practical experience so I could be wrong.
If oil is getting past the valve guides they might be worn and need to be replaced.  The manual will give information on how to check them and replace them, I have never done this myself.  The manual will show you how to check the valves and valve seats for wear as well and if they are still good then you will just need to re-seat them which is a very easy thing to do.  I believe you would do your valve adjustment after any parts are replaced and the valves re-seated because that process will change the distances.

Cleaning of carbon from the piston and head is a regular maintenance thing as it changes the flow of air/exhaust through the head and the carbon can heat up enough to cause the fuel to pre-ignite causing bad performance of the engine and excessive wear. 

I think you have the steps correct above except that you may not need a breather filter.  That can be cleaned out as it is mainly a large particle filter.  With all that oil build up though you will want to check the carb air filter to see if it has become saturated keeping air flow from the engine.  Check that no oil has been sucked into the carb as it would end up mixing with the fuel and causing smoke, fouled plug, etc.

That breather cover has a tendency to leak oil so make sure to clean both surfaces really well before putting on a new gasket and only tighten the bolt to the correct torque spec.  The one on my engine was over tightened causing the middle of the plate to bend in and the outside edges to bend out making it near impossible to seal properly and could cause dirty air to suck any leak directly into the engine.

Sounds like you have identified the problem though and odds are a cleaning and adjustment is all your will need.
When you clean the carbon off the piston look for the numbers that will indicate the piston size so you know if it has been previously rebuilt.
No scoring in the cylinder is good.  It does not mean the rings are not worn or the cylinder is not overly worn and needs rebuilding but at least it does not mean it definitely does need rebuilding.  The cylinder and rings will wear normally all the time.  Scoring in the cylinder would mean something actually scratched the surface such as foreign particles getting sucked in past the filter, in through oil or even bits of the carbon falling down the cylinder and jamming up in the rings.  The fact that you do not have evidence of that means the engine has either been rebuilt or it was reasonably well taken care of so those things could not happen.

Actually rebuilding these engines is not a terribly difficult thing but it requires patience and attention to detail.  I am so A.D.D. I am afraid of doing a full rebuild and screwing up the measurements for something.  There are also a number of tools needed which if you did not already have them would cost enough to make you want to send the engine out for rebuilding instead unless you were motivated to do it yourself and knew you would use those tools in the future.

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Mike and Trent, Thank you both for the great feedback and advice.

As far as the T is concerned, to my knowledge there is a T and an S on the flywheel. From what I have read the S is used for timing, go figure. I also read line up the T and you are at TDC. I need to dig around one this to make sure.

I guess as discussed I need to clean everything up at the very least, replace valves if needed, adjust clearances, replace gaskets, reassemble, and change oil. Hopefully at that point I will be good to go and have this engine smoke issue fixed.

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I don't know if this is correct but I found this about TDC on Kohler K series on another forum:

"there is a hole in the flywheel cover for timing.

on the flywheel there are 2 marks - one is "T" for top dead center and "S" I do not know what the S stands for, I think start

 

But I do know  that when you use a timing light you should see the "S"  and not the "T" 

I always start by gapping the points to 0.020 then check it with a timing light.  then adjust the points so that the "S" is centered in the timing hole

 

find out this about the "S" 

  the "S" mark inicates when the points begin to break, firing the spark plug."

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Ok, well, I guess I stand corrected...I'm a little confused as to what you found then.  Everything I've I ever read about reciprocating, 4 stroke engines (quite a bit, including an internal combustion engine class in my fourth year of engineering school) says Top Dead Center is the point at which the piston reverses direction, the crank and conn rod are in line, and the power stroke (or Intake) stroke begins.  Do you have a kohler service manual for your engine?  I think you can download them.  I've never worked on a Kohler single before, but I know I was able to download the service guide for my command two cylinder.  

I re-read your post, and noticed you said something about the valves being tight, then after you rotated the engine again, you were able to slide your feeler gages in.  If you were on the exhaust stroke instead of the compression stroke, it makes sense that the tappets would be tight to the valve stems.  The exhaust would be closing, and the intake would be opening.  Setting valve lash has to be on the compression stroke, because that is the only time you can be sure both valves are closed, and the tappets are loose on the stems.

Your Flywheel will rotate two times for every Cycle of the engine.  The four cycles of a 4-stroke engine are as follows:

  1. Intake stroke - Starting at TDC, the piston will pull down, with the intake open, and possibly the exhaust open slightly (this is called overlap, and is done for emissions). 
  2. Compression Stroke -  At the bottom of the intake stroke, the piston reverses and moves up, both valves close, and pressure builds. Your spark plug fires near the end of this stroke, igniting the mixture, and forcing the piston back down.  
  3. Power stroke.  This is the main event!  The explosion pushes the piston down, generating power.
  4. Exhaust Stroke -  At the end of the power stroke, the piston reverses again, and forces the spent combustion gasses out of the exhaust valve. Intake opens just before or just after TDC, and the cycle repeats.

Since the flywheel rotates twice per cycle of the engine (piston only moves up and down once per revolution),  its possible for the "T" to be in the window, at TDC of the exhaust stroke, and you won't be able to set the lash.  

NOTE:  Don't be offended if this information is redundant to you.  I'm only posting for clarification, and to be sure everyone posting replies is working from the same knowledge base.  

 

Edited by Mike_H
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Thanks Mike, No offense taken. This is what I need, members like you helping me that know more than I do. That is why I am posting on this repair.

I don't know a whole lot about engines, hence why TDC is something I am not sure about. I do have the Kohler service manual. It just says TDC is the top of the compression stroke.

So the flywheel fully rotates 2 x per cycle of the engine. The piston rises to the top of the cylinder 2 x. The question is which time is it at the top of the compression stroke?

From the left side of the tractor, the T is upside down with a line underneath it through the timing whole. The piston is flush with the top of the cylinder, the valve heads are slightly peaking open, the valve stems are tight to the tappets, and I can not get a feeler gauge in between. So maybe like you said this is not TDC, but opposite. If the timing whole was on the opposite side of the flywheel or the right side of the tractor, when you rotate the engine another 180 degrees the T would be upright with the line over it, that must be TDC. I saw some of the Kohler's had the sighting hole on the right side of the tractor near the starter. This may explain the contradiction we are finding.  

If I rotate the engine 180 degrees, the piston is flush, and the valve heads are flush, the valve stems are slightly separated from the tappets, and I can get the feeler gauge in between. The exhaust side measured dead on .018 and the intake measured slightly off at .007. So if this is TDC and the only adjustment needed is .002 on the intake side, then what is causing my burning oil issue? Oil seems to be coming up around the tappet, is that normal? Oil was burning or leaking out from the breather. Do the pictures I have taken explain what is going on? Oil is also being burnt around a stud that comes through the head gasket and head near the piston.

Thoughts?

Thanks

 

 

Edited by jsarro
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When you're at TDC on the compression stroke, the Piston should be at the top of the cylinder, and the valves should be closed.  I'd forget about the "T" for now, and get the engine in that position.  Then make your measurements.  The intake clearance being off won't probably be the cause of your oil burning concerns, but it could cause it to be harder starting than normal.  It can definitely cause you to be down on power, though I doubt you'd notice that little of a difference on one valve.  

Burning oil is generally caused by two things, which have been identified...the breather not working properly or bad rings on the piston, which causes blow-by.  

The oil you are seeing past the tappets is supposed to be there, it is what lubricates the wear points between the tappets and valve stem.  Shouldn't be puddles, but a little bit of oil is normal.  

 

I'll re-read this whole thread again at lunch and see if anything else jumps out at me.

 

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Thanks Mike. I agree on the TDC.

I think we have solved the cause of my oil issues.

I think part of the oil issue is the breather as you said , I think the remaining is oil coming up from below around the stud threads. I had a friend look at the pictures and my story and he said take those studs out and coat the threads with height temp. RTV and reinstall. This would make sense as long as that it is possible for the bottom of those studs to be making contact will oil from below. I don't know exactly how this engine is built. In addition the head gasket is damaged and the oil is leaking out around the stud and burning of the heat shield.

So the oil appears to be coming up from around the stud bolts and then burning off on the top of the piston. My friend said the carbon build up maybe disrupting compression and cooked the head gasket.

I think what I am looking at now is:

Clean head and piston

Remove and reinstall stud bolts with RTV high temp

Replace head gasket

Replace and reseat valves, check valve guides, adjust valve tappet clearances at TDC.

Clean breather, replace both gaskets on breather.

Change oil

Reassemble tractor, and hope for the best.

The tractor has plenty of power without hesitation, it just starts on the hard side and smokes or burns oil from the breather, around the stud bolts, and from the gasket.

I really hope this takes care of it all. I do not want to have to tear the engine down completely and deal with the piston, rings, and cylinder.

Any thoughts?

Does this sound logical?

Is there any way to know at this point if something worse is wrong?

Thanks

Jack

 

Edited by jsarro
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