Colt Case Ingersoll Garden Tractors

Everyone who has an Onan knows they vent crankcase to the breather . This can cause oil buildup in air filter housing . The paper filter love to absobe the oil as well as being sucked down the carb . When cold out an oiled filter does not flow very well making hard to start at times . This is my solution to it . I bought one of these and installed it like so . Short test yesterday , worked well . Was amazed how much water was caught in the can . If works well I will put one on the Snow Blower tractor as well .

Actually, the oil getting as far as the air cleaner is a problem with the engine. It is not a normal thing with age or just the way it goes. It does mean that you have an air leak in your engine crankcase. With a leak, what is happening is that each pulse cycle of the engine, and through the leak, the engine is drawing in too much air. The vented air is picking up some oil on its way out through the crankcase vent.

The tappet cover gaskets can leak, which indicates that your engine is running lean. When it runs lean, it runs hot, so the cover seals are turned to stone and cannot seal like that. The dipstick can leak at the top of the tube for all models and the dipstick tube for the P-Series engines. The crank seal at the cam cover end can also leak, and again, it is usually due to excessive engine heat. You would think that the crank seal would also leak oil, but it is above the oil level in the engine and does not get any high-pressure lubrication.

This whole thing does affect the pulses to the fuel pump as well.

Often, there are many things that are related, and it is part of the diagnostics. This is also why some guys do not like to talk about fixing their stuff. Some guys understand that fixing the engine is almost never fixing one thing. Others do not get that, and they are the ones who "fix" their stuff until it is unfixable by them. It is all part of learning how things work and are interrelated. Nobody is born with that knowledge.

This engine has done this from day one , My other Onan does it as well but not as bad . Both have great compression . Both have had all seals and gasket replaced at one point with no change to oil in breather . I get what you are saying , but have done all that .

The Onan on my 446 for winter snow removal has no crankcase breather problems. I had an Onan CCK on my 646 and it always had crankcase breather problems. After trying to fix that problem I finally repowered the 646 with a Honda and end of problem. Harry

I get paid to fix them. I have fixed that issue. It is not the rings, compression, or even blow-by issue. I am batting 1000 on my tractor rescues. The thing is, we have all mostly bought very old tractors. So, of course, they need fixing.

I will rarely try to override what the engineers at Onan created. I consider the Onan the best engine ever used in a garden tractor, plus the many other applications. A professional leak-down tester is the only tool that can make it an easy job. It is amazing how many air leaks you find when you put about 80 psi into the engine. (Separate topic, but speaking of leak-down, almost every engine has intake valve leaks. It is carbon on the valve face. It is the number one way to increase engine compression.) The crankcase vent fails to control the excessive positive pressure created by the engine's suction pulse.

I have seen that race engines need a catch can for the oil coming out of the engine crankcase vent, so I know that it is sometimes normal. You fixed it your way, and I restored it as much as possible. We each completed it.