I have a 15 HP OHV Kohler engine that is in a Scotts lawn tractor. When I try to start it, it doesn't fire up, there is alot of blow by coming out the carb. I checked the compression with a tester & there is no sign of any compression. I removed the pushrods so the valves do not open & the blow by still comes out the carb. with both valves closed still no compression.
Any idea what the problem is?
Thanks!
Have you checked for a bad head gasket?
Check the intake valve springs or the intake valve shafts to be sure they aren't stuck open. Another cause could be excessive carbon build up on the intake valve causing them to not seal.
If you've gone this far, you could try a compression leak down test. If you still have the push rods out, you can use or get an adapter that will allow you to pressurize the cylinder(s) with air by removing the spark plug. Apply 70-80 psi air directly to the cylinder (the cylinder may go to BDC (bottom dead center) but if you don't have any push rods, the valves can't open.
Listen carefully - if you hear air leaking out of the carb, it's a bad intake valve. If you hear air from the exhaust, it's an exhaust valve. If you hear air from the crankcase breather, it's piston rings.
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Intake valve was bent & not seating.
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