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JamesC-120

Kohler K301 compression release malfunction?

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JamesC-120

I have a Wheel Horse C-120 with a K301 and it ran perfect the day before but I went to start it and it would not start. It has gas and spark but No Compression! It worked perfect the day before. So I pulled the head off and it appears the valves are not working correctly. My assumption is that the compression release is not disengaging once the engine gets spinning. If I put it at full throttle and try to start it I can get it to start after a while and it runs perfect but getting it going is horrible. Has any one else had this problem? Help would be appreciated. 

 

Thanks 

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Terry M
1 hour ago, JamesC-120 said:

it appears the valves are not working correctly.

What are they doing...or not doing James?

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pfrederi

Compression release only works on eh exhaust valve.  It will open just a tad for just a second as you come up the compression stroke.  What is your doing?

 

You could have a stuck valve or trash  / flaw in the valve seat.

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wallfish

Choke working properly? Dirty carb? Water in the bowl or tank? Fuel pump weak? Could the carb bowl be leaking? Will it start easily if you squirt a little fuel into the carb?

Check for and eliminate any fuel delivery problems first, if there is any.

Edited by wallfish

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JamesC-120

Well there is nothing wrong with anything else it is definitely compression related because it only has 10 psi. The exhaust would be fully open then start to close but the intake would start to open before the exhaust was fully closed. So they would both be about half way open. The valves are not stuck because they do close all the way. 

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rmaynard

The compression release mechanism is designed to 'fail safe'. In other words, if anything in the mechanism was to fail, it will drop out of the release mode and give you full compression all the time.

 

Stupid question, but when you have the head off and looking at the valves working, are you rotating the engine in the clockwise direction as viewed from the flywheel side?

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pfrederi

Compression realease only works on the compression stroke.  if i understand your description on the exhaust stroke the intake valve opens to soon????

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JamesC-120

I believe I rotated it clockwise. 

1 minute ago, pfrederi said:

Compression realease only works on the compression stroke.  if i understand your description on the exhaust stroke the intake valve opens to soon????

Yes that is what I though that the intake was opening to soon. Maybe I should check the valve adjustment, it may be way to tight.  

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wallfish
3 hours ago, JamesC-120 said:

Well there is nothing wrong with anything else it is definitely compression related because it only has 10 psi.

OK but...

You can't really do an accurate compression test on an ACR engine so it's best to do a leak down test. The ACR is Automatically Compression Releasing like it's designed to do.

If it is "running perfect" after you get it started, then I would assume the valves are working properly.  I'd guess it would probably backfire if the intake opened when the exhaust is open while it's running .

:twocents-02cents:

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JamesC-120

I could try doing a leak down test. I have another c-120 with the exact same engine and when you turn the engine by hand it will hit a hard spot, when compression builds up and then other hard spot right after it, Which is normal but the engine I'm working on only builds up compression in only one spot when rotating by hand. 

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oldredrider

Since you said it ran fine the day before and nothing changed, given your description of how the valves are acting, you have a stuck valve. Period.

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JamesC-120

If the valve is stuck then how come when it starts it runs flawlessly?  Anyway I adjusted the valves just for the heck of it and the clearances were pretty tight. So I opened them up to the stock spec. But it had no effect it still does them same thing. 

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JamesC-120

I just did a leak down test and it does not seem to be loosing compression through the valves or the rings. I did another compression teat and same thing 10psi but I aslo did a compression test on my other k301 and it was 60 psi. I know it for sure that the valves somehow are not closing before another valve opens but for some reason once it starts it fixes it self somehow. But I just don't understand how. 

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JamesC-120

I think I might have found the problem. So I took the head off the other one of my k301's and watched the valves very closely and when the exhaust valve gets held open for the ACR it is opens just the slightest amount, barely noticeable. But when i watched the other one when the ACR holds the valve open the valve opens much big and stays open longer. I"m not sure how that is possible but I have never really looked at the ACR on the cam and looked at how it works. 

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pfrederi

Sounds like you are going inside.  As I said the ACR only very briefly opens the exhaust valve and only opens it a very small bit. Something is wrong there...but it still doesn't explain the intake and exhaust open at the same time as you mentioned here at one point.:think:

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JamesC-120

My other k301 that runs fine does the same thing, the two valves open slightly at the same time. I think I am going to pull the cam shaft cover off to start and see if anything is noticeable wrong with it. 

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pfrederi
1 minute ago, JamesC-120 said:

My other k301 that runs fine does the same thing, the two valves open slightly at the same time. I think I am going to pull the cam shaft cover off to start and see if anything is noticeable wrong with it. 

Sorry I misunderstood I thought they had an extensive overlap...

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rmaynard

I don't know if you have done this already or not, but look at section 9 of the Kohler Service Manual. It is a complete explanation of the ACR with drawings. Before digging too deep, read and follow the procedure for checking the ACR operation.

 

 

Link: 

 

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Terry M

James, maybe you could do a quick video to show us how the valves are opening and closing ??( in respect to the timing)

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prondzy

It sounds like the weights for your ACR, or the spring have stuck or failed. The ACR weights work like an advance mechanism in a distributor. When a certain rpm is reached (I beleive its around 600) the weights overcome the spring and the tab that usually pops the exh. Valve open during starting is drawn inward and becomes part of the cam lobe. Which if one of the weights is stuck the ACR will be on all the time and if it were to hold open a little over the intake stroke while running the engine would run just fine because the exhaust at that point is "inert" for all intensive purposes and would act like an egr valve on a car.

 

 

Anyway... if you don't want to tear into the block just yet James I would try a cap full of sea foam in the crankcase to see if gunk has stuck the weights. Once you get it up and running work the motor for a while to get the oil splashing around and hot to see if the ACR unsticks. Once it cools down check the valves for proper operation.

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JamesC-120

I understand how the ACR works now and I pulled the camshaft cover off and the ACR seems to be working perfectly fine. The spring is still on and the flyweights move in and out as they are supposed to. When I turn the engine over by hand everything seems to being working exactly how the Kohler manual states it should. By the way I did put in sea foam about 2 days ago and it did not help.   

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953 nut

I know that you have been laser focused on the valve train and said you have spark; but, have you inspected, cleaned and adjusted the ignition points? The points have a great deal to do with timing of your ignition and could be the problem.

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JamesC-120

You know I have been thinking the same thing and I just cleaned the points and adjusted them. I tried a different spark plug but no change. When I check the spark it is a nice blue spark and not weak at all. 

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prondzy
On 5/2/2016 at 7:59 PM, JamesC-120 said:

. If I put it at full throttle and try to start it I can get it to start after a while and it runs perfect but getting it going is horrible. Has any one else had this problem? Help would be appreciated. 

 

Thanks 

James I just tries to re-read your original posts, forgetting about the valves and timing/ignition what is making your beleive there is something wrong?  This part I quoted, I beleive in the WH manuals it states full choke and half the lottery at cold startup. And if it were warm you would want full throttle to startup.     .....just trying to see if we are missing something. 

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JamesC-120

The day before it had any problems it would start immediately like any good Kohler should. The next day it would not start except and full throttle no matter if the engine is cold or warm and you would have to crank it for an excessive amount of time. It has a significant  amount less compression that my other k301 and when I checked the compression on my good k301 it has 60psi and the one I'm working on has only 10psi. I know you can't get an accurate reading but it can give you an idea of the difference. But once I get the engine running it seems very strong and has lots of power. So I figured it had something to do with the compression release because that is the only thing that changes when the engine starts. When it is about to start it will run at a super low rpm for about 3 seconds then all of a sudden speed up like normal. It seems like when it does that something changed and it will take off all of a sudden. Like it just got a boost in compression like the compression release just disengaged. 

Edited by JamesC-120

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