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Dead Cylinder


rocko

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I've got a 20 hp Kohler Magnum engine with a weak cyl. Compression test show 50 psi(dry) and around 100(wet). I assume the rings are the problem. Are these engines a nightmare to tear down and reassemble or are the fairly simple? I would just like to know what I'm getting myself into.:) Thanks, Mark
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Hi, To get the crank out you have to strip it clear down and split the crankcase. I would put a tablespoon of oil in the sinning cyl spark plug hole, turn the engine over several turns and recheck the compression. If it is still about what it was, it is probably a valve that needs ground, which I would be more likely to suspect. This can be done without removing a cylinder. Just remove the cyl head and the valve chamber cover and grind the valves. The cylinders can be removed without removing the crankshaft. If you are going to replace the rings,and not the rods,[which I would not do] just take the base nuts off the cyls and pull them off. If for some reason you want to remove the cylinder without replacing the rings, loosen the base and pull cyl off until the pistons are far enough down to get the wrist pin out and leave the top of the piston and rings in the cylinder. To retorque the cyl you need to buy a special socket from Kohler Spl Tools. My 2 cents worth and its free, value accordingly. Al Eden
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Mark, I retrieved a M20 from the junk. All that was wrong is that is was all carboned up. Cleaned it, reground valves, and it is now the engine in a winning pulling tractor. Never pulled a cylinder.
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it shouldnt be to hard to teardown and pull the pistons and put new rings on it, more serviable(easier to work on) engine then the old kolher kt series. Did you try to pull the head and lube the piston wall with 30wt oil?...just squirt some up on em, might help seal the existing rings, just let er sit for a while....turn motor over by hand slowly-back and forth, and clean the top of the cylinder wall ridge and top of piston(@ TDC) when done. that should help if looking for less expensive alternative.just a thought though. good luck!
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Thanks Al, when I checked the compression with oil in the cylinder it jumped up to around 100 psi. Do you suggest doing a total rebuild rather than just replacing the rings? I would just assume do it right the first time.:) BTW... How many special tools do you need and how hard are they to come by? PLEASE ADVISE, MARK
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Mark, Before I tore it all apart, I would pull the head and valves and ck them out. I'm betting on the valves no more than the compression came up. Good luck, Al Eden
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Hello Mark. When I used to work on cars I would use the compression tester hose and put shop air into the cylinder. You will have to hold the engine on the compression stroke at top dead center because the air will make the engine turn over. May have to turn down the air pressure for a smaller engine. I used a steathiscope or a hose and listened in the carb, exhaust, and crankcase. Usually could tell where the leak was. Might give this a try if possible.
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