Example of excessive crankcase pressure

kohler command pro ecv650 efi with excessive crankcase pressure

[@rhinely850]

Crankcase pressure fluctuation is also normal, and can be caused by the downward stroke of the under side of the piston on both intake and exhaust stroke. The upward stroke (top of [piston) compresses the gas/air mixture, and 2 strokes later pushes out the exhaust gases above the pistons. It is not always due to blow by pressure past the rings during combustion.

[@projectblack2462]

I have 2 push mowers thatll do that. But they still pull a vacuum. My small engine guy says as long as it pulls a vacuum and doesn't read pressure, then its okay. He says the crankcase ventilation system is circumvented when you remove the oil cap. So itll mist some oil out. Bad blowby will cause the oil to smell like fuel and make it flammable. Yours does seem way excessive. You can see combustion gases coming out of the crankcase.

[@brettbuiltit7504]

Its definitely excessive. A new crankcase breather got it running better to finish out the season. Its got over 2000 hours on it. Blow By for sure. Its getting rebuilt as soon as the snow flies.

[@projectblack2462]

@@brettbuiltit7504 lol. Well at over 2000 hrs it dont owe you anything. Thanks for the vid!

[@techman1274]

Blow by can be caused by a failing head gasket. Did you do a compression check? Its cheap to replace the head gaskets and adjust the valve lash and rebuild the carburetor. That engine sounds like it runs to smooth to be blow by.

[@acruzcruz8578]

Hello I read the other comments. I have the same problem. I was asking if you replaced the entire block of the motor or just the breather cap? I’m a bit confused, it will help me a lot if you can explain to me. Thanks

[@reekinhavok420]

my brand new timecutter does this im calling kohler they better fix this crap not even one hour on it

[@xx3868]

Hi, i have a little Yard King 4 stroke 24.5cc and i realized the valves are all one part with the cylinder SO is there a path for the pressure to go up into the valve area past the rods and out through that hose there as they also have another hose and nipple on side just under piston area which sends out lot of oily goo into the air cleaner then it goes up a tube and gets sucked into the carb and burnt. Makes the carb throat a little dirty perhaps. So 2 hoses going to Air Cleaner. question- If the gases from crankcase cant get up to the top out through that top hose i HAVE to have that oily hose breathing going to A/Cleaner and CANT Block it off? or crankcase gases will explode seals? So other option is maybe connect a fuel filter to end and let it take all the crap and change it but it would also allow backflow back into CC?. so no good? Any ideas.. thanks?

[@COFFEE-e3p]

causes / fixes ???

[@michaelhenderson168]

How did you fix it?

[@brettbuiltit7504]

Put in a new crankcase breather to get me through the season. Theres plenty of blow by too, probably why it was throwing oil 5 feet out of the cap. As soon as the snow flies its getting rebuilt. Its got well over 2000 hours on it.