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my dad has a kohler model ch25 spec68543 it is running rough has white smoke coming out of the breather tube. the coils checked good new plugs did a compression test 150 psi on one other one 120 psi any help would be greatly apricated...

bear369 said:

my dad has a kohler model ch25 spec68543 it is running rough has white smoke coming out of the breather tube. the coils checked good new plugs did a compression test 150 psi on one other one 120 psi any help would be greatly apricated...

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What does “running rough” mean specifically? How many hours? Regular oil changes? Checked the cooling fins and engine for debris by removing shroud and tins? How did you check the ignition coils? Also, need to do a leak down test. 120 plus psi on cylinder should be plenty to run well.

Tiger Small Engine said:

What does “running rough” mean specifically? How many hours? Regular oil changes? Checked the cooling fins and engine for debris by removing shroud and tins? How did you check the ignition coils? Also, need to do a leak down test. 120 plus psi on cylinder should be plenty to run well.

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Kohler Command says 160 minimum per Kohler

used an echo pet 4000 spark tester cooling fins are clean it just happened the other day cold or hot it just runs rough a slight popping sound in the muffler as far as hours don't know dad's lawn mower did not think to check it.. oil changes every cutting season has a small lawn had replaced the other head gasket years ago with the updated new designed one checked oil level good no smell of gas in it. he doesn't have an air compressor for the leak down test..

Is it OHV? Adjust the valves?

Fuel or water in gas? Drain and refill tank. Replace fuel and air filters.

Cfs said:

Is it OHV? Adjust the valves?

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Why do posters just throw something out just to hear their heads rattle?

Why don't you do your homework first before sounding like an idiot? Valves on this engine are auto adjusting due to hydraulic lifters.

Does it use any oil?

Freddie21 said:

Fuel or water in gas? Drain and refill tank. Replace fuel and air filters.

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I agree. Sounds like moisture in the gas to me.

thanks to all that posted.. we pulled the head on the side with the lower cylinder pressure found a bad head gasket.. crack near the exhaust valve blow back in the crankcase will report back after we change it..

bear369 said:

thanks to all that posted.. we pulled the head on the side with the lower cylinder pressure found a bad head gasket.. crack near the exhaust valve blow back in the crankcase will report back after we change it..

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Probably should go ahead and change both while you are working on it. Not that much more work to do the other head when the engine is already basically torn down.

I always replace them as a set. Not as fimiliar with the CH but the CV. First one I ever tore down with blown head gaskets I took one look at it and said it needs fire rings on the gasket. 20 years later they finally did it. Best indication of a blown head gasket is a fouled plug. Compression test, cylinder leak down test and crank case vacuun test may not show it. Have never missed one yet.