What causes excessive crankcase Blowby?
When you combine a large cylinder bore, high cylinder pressure through turbocharging, many hours of use and marginal maintenance, excessive blowby is the result. The leakage of any combustion gases, air, or pressure into the engine’s crankcase is considered blowby.
Can too much fuel cause Blowby?
In a GDI engine, fuel is injected into the combustion chamber downstream of the intake valves, eliminating the cleaning effect of fuel washing over the intake valves. This means that blow-by can build up on the backs of the valves even faster, impeding airflow and causing potential running issues.
What can cause high crankcase pressure?
A few things can cause excessive blow-by apart from worn cylinders or rings. Powerful spikes in crankcase pressure are a classic sign of a blown head gasket, or a cracked engine block. This is especially true if the gases coming out of the breather hole carry with them a strong stench of raw gasoline.
Can a blown head gasket cause Blowby?
Registered. Sounds like a head gasket. Worn or broken rings can cause excessive blow by but will not push coolant. You can inspect the cylinder walls when you have the head off.
What does it mean when your blow by tube blows out?
Anymore indicates a valve or ring problem. If you don’t have a gauge setup to measure it just put your thumb over the end of the blowby, you should be able to hold it there without blowing off. Interests:Diesel powered anything, from locomotives to diesel lawn mower!
What happens when you block the blowby at high pressure?
Most often if you have a problem the pressure is considerably higher than the 5 psi I alluded to. When you block the blowby at high pressure the dipstick is the first place that blows out, your thumb will usually feel the higher than normal pressure instantly though.
What should the pressure be on a Cummins blowby?
Not sure on a Cummins but other diesel engine makers say the pressure coming out the blowby shouldn’t exceed 5 psi. Anymore indicates a valve or ring problem. If you don’t have a gauge setup to measure it just put your thumb over the end of the blowby, you should be able to hold it there without blowing off.
What to do if oil comes out of blowby tube?
When you block the blowby at high pressure the dipstick is the first place that blows out, your thumb will usually feel the higher than normal pressure instantly though. A manometer is cinch to make and will cost you 10¢. All you need is loop of clear tubing filled partially with water taped to a 1×4” and  a tape measure.