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GregF

Kohler 10hp engine knock at idle

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GregF
I just got a Landlord 7010 with a 10hp Kohler, model K241S, from my uncle. It has an engine knock at idle that I am trying to track down. Anyone have any ideas about what the problem might be? It runs fine and is there is no noticable knock at anything above an idle. My uncle had the crank turned and installed a new piston and connecting rod. This was done because the dipper on the original rod broke off. I'm not sure if the engine seized or the broken dipper was discovered some other way. I took the oil pan off and the rod turns easily on the crank but there doesn't seem to be any excessive play. There does seem to be a lot of play where the governor gear (at least that is what I think it is) turns on a shaft that is pressed into the block. I don't have a shop manual on this engine. Does anyone know the tolerance on the connecting rod to the crank? How about the governor gear to the shaft it turns on? Am I on the right track? Maybe it could be something else? I welcome any insight from you guys that have more experience with this engine. Thanks, Greg

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maxtorman1234
I find The governor gears are usually pretty loose, but dosent effect the motor. It seems odd it only knocks at idle, are you sure it is a knock? or just some other noise?

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Salthart
While you have the engine off and the oil pan off of it, Stop by a garage or a parts store and buy/borrow some "Plasti-guage". It will look something like a hair. Lay a piece on the rod cap and re-torque the cap. Then check the width of the plastic and match it to the guide on the paper. I don't have the specs for that engine, But I'm sure someone can post it for you. Did you ask if the rod was changed when the crank was turned ? Also, If you have slack in a rod bearing, You will hear it as a quick sound as you rev and let off.. Its is something like the sound/speed of a woodpecker brrrrratttt. The speed of the knock is often key to understanding what causes it but other things outside the engine can sound like an engine knock.. Like loose driveshaft bolts. And more that once I have seen a loose coil bump the flywheel as the magnet passes.. Good luck..

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BLT
There is a possibility that you might have a carbon build up in the fire dome area of the cylinder head which will cause a knock. Remove the head and check to see if there is a piston impression in the head, carbon removal is a must.

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GregF
Thanks for the responses so far. I will check to see if there is anything helpful in the service manual. I am familiar with plastigauge and plan to use it if I can find out what the tolerances are supposed to be. The rod was changed, presumably it was matched to the reground crank but I would like to check it. The knock does not sound like a typical rod knock so I don't expect to find any problem there. The head is off and there is no carbon at all. My uncle is pretty meticulous and removed all that when he replaced the piston and rod. It hasn't run enough since to have any built up.

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GregF
The Kohler service manual has already been a big help. Thanks GregC for pointing me in the right direction. In my first post, I incorrectly identified the suspected loose gears as timing gears. The gears with suspected excessive play are actually balance gears. The service manual also lists tolerances that I can check. I won't be able to get back to the engine before the end of the week but I'm anxious to dig back into it. I'm still open to any other ideas that anyone has, in case this doesn't solve my knocking problem. Greg

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Al
Hi. Sounds like it might be the camshaft. You can tell by listening when you have the sump off and if you rock the crank back and forth at the point where the exhaust lobe is just coming down and the intake is just touching the lifter. You will hear a click because the camshaft is worn on the inside where it turns on the shaft through it. It will make a rather loud knock at idle. If you rock the crank back and forth you can identify it. If that is it, a new camshaft is the fix. If you ascertain that is what is wrong, it will run that way for years, just be noisy at idle. Al Eden

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GregF
Finally got around to putting the engine back together after tearing it down last month. Al was right on target. Replaced the camshaft (not inexpensive from my local dealer) and the knock is gone. Thanks to all who helped. It's raining here in GA this week so I haven't had a chance to run it much. I'm looking forward to mowing this weekend and trying out the Vac my uncle gave me with this tractor. Greg

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