# 1 cylinder running lean



## Wolf1058 (4 mo ago)

I have a 28 HP Koehler Courage that has one cylinder turning the exhaust pipe red. Other side is good. Initially it was not running on this cylinder and I found that it had a push rod bent which I think was caused by a backfire.
Compression is about 130 in both cylinder and a leak down test is in the green for both cylinders.
Carburetor is new and I don’t see how that could be the problem since the one cylinder is running fine. 
Any thoughts will be appreciated.


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## sixbales (May 18, 2011)

Good Morning Wolf, welcome to the tractor forum.

One thing to check is the exhaust valve. It might not be fully closing?? Another thing to check is the flywheel key for shearing, throwing the timing off.


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## Wolf1058 (4 mo ago)

sixbales said:


> Good Morning Wolf, welcome to the tractor forum.
> 
> One thing to check is the exhaust valve. It might not be fully closing?? Another thing to check is the flywheel key for shearing, throwing the timing off.


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## Wolf1058 (4 mo ago)

Thanks, I’ve already checked the flywheel key. Will see about the exhaust valve this weekend


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## 2billt (Aug 7, 2011)

I'm gonna think if your leak down was good that valves are seating. You didn't state at what pressure the leak down test was done. 
I will assume you re-adjusted the valve lash, the info I have is .004 / .006"
I've worked on a couple of these that had overheat issues via exhaust pipe glow. Both of them had debris in the cooling fins, pulled the shrouds and blew them out.
Another issue comes to mind like restricted exhaust, being that you had a backfire it may have dislodged carbon or ? 
Take a temp reading of the both exhaust pipes when it glows, if you can.


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## Wolf1058 (4 mo ago)

The leak down test was done at about 35 - 40 psi. I did check and adjust valve lash to .005 on both cylinders. All get something to check temps. 

Thanks


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## 2billt (Aug 7, 2011)

My first test would be using 100# for a leak down with cylinder at top dead.


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