I just put a B16a in my integra. Dont ask why I needed a car and this was the first montor I could grab. When its at idle and I pull the oil fill cap air pumps out like you have you hand by the exhaust tip. When I give it gas it stops. Is this ok. I know it aint normal. Whats could cause it..

Thanks

 

Maybe the PCV valve isn't working properly or you have excessive piston ring blow-by or a combination of both.

 

I was told the motor was from a 99 civic si with under 40000 miles. Its had a totally rebuilt head. This is a local dealer that has a very good rep. Thanks i look into that.

 

Sounds like normal crankcase pressure to me. At lower rpms, the pressure in the cylinders has more time to leak past the rings, at 4k, it doesnt have enough time to leak past.....plus there is probably something to do with the PCV system, but that relieves pressure.

 

Pcv valve checked ok. Pulls a vac and rattles when shaken.