Oil Problem

[deanodominy]

I recently removed my oil filler cap and found that there was air blowing out. It was not excessive but is this normal. Could anyone help me with this please. I was a;ways under the impression that you were only suppose to get a vacuum. Any suggestions would be very helpful.

[GT4 BOOSTER]

check the rocker cover ventilation hoses ( breather pipes ) arn't blocked

[andy_twincams]

there should be some pressure,but not loads

[sotal]

it should blow some oil out just not loads, I did lots of tests because I was losing oil and a friendly mechanic did a few tests etc, he took the cap off and a bit of oil blew up (enough to make his hand quite wet) he said that didn't look too much, but to check to make sure he took the dipstick out with the engine running and nothing came out of there so he said it was fine.

[mikeb]

Increase the revs and it should stop. It is an effect that occurs due to the pistons moving slowly and pumping air around inside the crankcase. At higher (1500 rpm upwards) the pistons are moving fast enough that the air behind them just compresses and equalises instead of being pushed around so much, and the blowing effect from the oil cap should reduce. If not, then you may have a blocked breather or broken piston ring.