Kohler CH740 power issues.

F150Fan80

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Well my first real post on the forum, here goes.

I have a Kohler Command Pro 27 (according to the carb cover anyway) that has a loss of power at speed. I know, not a another one. Lol. This is a CH740-0037 Morridge engine with serial number 3631007811 and a build date of 11/6/2006. This is in a 2007 Grasshopper 727K2 with a manual height (want Powerfold) adjust 3461 deck. The engine wants to die when the deck is engaged. Sometimes it does die. Also it is a little hard starting. Now usually I can throw whatever I want at this machine to mow and it takes it all with no issues. The last couple of mows this year was a little rough since it would bog down and really struggle is spots where it would just chew the grass up and spit it out.

Here's the list of things that I have looked through or changed out trying to chase this issue down. I have already changed out the head gaskets about 400 hours or so ago. The engine has about 880 or so on it now. I have changed out the fuel filter with a Kohler one. I have changed the fuel pump, rebuilt and cleaned the carb, replaced the coils. I even checked everything on the deck and it moves with relative ease. I have replaced all the drive pulley bearings for the hydros. I have even changed the PTO clutch thinking it was wearing out. That turned out to be true but not the issue.

I haven't checked compression or fuel solenoid yet. I plan on doing that this afternoon. I'm starting to run out of ideas here. If there is anything else that I could check or send me in the right direction it would be greatly appreciated. This machine may become my snow removal machine so I want this running great. That is a discussion for another thread to be started soon. :laughing:

Thanks for any advice in this!!

Edit: Can we add this forum to Tapatalk? Maybe a different app? Thanks!!
 

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tom3

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I suspect the compression test will lead to the problem. Valve adjustment or loose rocker (hydraulic lifters?) , push rod(s) bent, maybe a head leaking even though they were replaced at one time.
 

F150Fan80

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I suspect the compression test will lead to the problem. Valve adjustment or loose rocker (hydraulic lifters?) , push rod(s) bent, maybe a head leaking even though they were replaced at one time.

I was unable to get to the compression test yesterday so today will hopefully lead to some answers, or more questions. LOL I do believe this has hydraulic lifters so there shouldn't be any valve adjustment. I do think that I have read that the lifters can fail in these leading to compression issues. Knowing my luck it will be something more expensive though. :rolleyes:
 

F150Fan80

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I suspect the compression test will lead to the problem. Valve adjustment or loose rocker (hydraulic lifters?) , push rod(s) bent, maybe a head leaking even though they were replaced at one time.

Well I was able to do the compression test. I ran the mower at about half throttle outside for about ten minutes or so and then brought it back inside the warm shop. Here is what I found. One side was 125-135 psig and the other side was 90-100 psig. Needless to say this wasn't the outcome I was looking for. The side with the higher compression had some oil on the plug. Not sure what I am going to find with this yet. Now it is time to clean the benches off to pull the motor and go from there. I should be able to pull the heads with the engine still in the frame which I might do but I feel that it will be easier to just do it on the bench.
 

bertsmobile1

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Before you go ripping the engine out test the governor
Start by resetting it then go for a test mow
If it is no better then put a length of string / wire on the governor arm so you can manually over ride it to give the engine more throttle when it is under load.

Did this just happen over time or did it happen after you had done something
Do a double check that the choke is fully open when the mower is in run mode.
Also check that the throttle cable has not slipped so the throttle is not putting enough stretch on the governor spring.
 

F150Fan80

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Before you go ripping the engine out test the governor
Start by resetting it then go for a test mow
If it is no better then put a length of string / wire on the governor arm so you can manually over ride it to give the engine more throttle when it is under load.

Did this just happen over time or did it happen after you had done something
Do a double check that the choke is fully open when the mower is in run mode.
Also check that the throttle cable has not slipped so the throttle is not putting enough stretch on the governor spring.

I more I think about I believe that it has been more gradual but seems to have gotten much worse the last couple times I have mowed. Unfortunately we have snow on the ground now and I'm not able to test mow currently. I have reset the governor a few times due to surging when unloaded. I don't see a way however to not pull the heads since this engine needs at least 160 psig in each cylinder. The choke appears to be moving freely and completely in both directions. I guess I could just engage the deck and move the governor arm by hand and see what happens. The low compression numbers do point to head removal though.
 

ILENGINE

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Well I was able to do the compression test. I ran the mower at about half throttle outside for about ten minutes or so and then brought it back inside the warm shop. Here is what I found. One side was 125-135 psig and the other side was 90-100 psig. Needless to say this wasn't the outcome I was looking for. The side with the higher compression had some oil on the plug. Not sure what I am going to find with this yet. Now it is time to clean the benches off to pull the motor and go from there. I should be able to pull the heads with the engine still in the frame which I might do but I feel that it will be easier to just do it on the bench.

According to Kohler those compression readings are low for both cylinders. Kohler says 160+ for the Command twin engines since they don't use compression release.

Was typing up my response when you posted about tearing the engine down on the bench.
 

Fish

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Unplug one plug wire and try to start. Then plug it back in and remove the other one and try.
Tell us what you find.
 

F150Fan80

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According to Kohler those compression readings are low for both cylinders. Kohler says 160+ for the Command twin engines since they don't use compression release.

That is where I found those numbers myself, although I almost missed it. Thoughts on pulling the heads and inspecting?
 

F150Fan80

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Unplug one plug wire and try to start. Then plug it back in and remove the other one and try.
Tell us what you find.

I assume you're wanting me to see if it is running on one cylinder or not and to try and figure out which one could it be? I could do this. I will say though when I start the engine cold it seems to fire on one cylinder and then will run on two after 10 seconds or so. After it starts running on two it seems to stay that way.
 
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