Took oil filler cap off today when engine running, and was surprised that there was quite a chuff chuff of gas blowing out of the oil filler cap.

Blipped throttle to 2- 3 k and this chuff stopped?

Is this normal???


Crankcase vent also chuffed once oil cap back on, this stopped less when revved.



Engine is 6000 miles since rebuild and run in carefully - under 3k rpm for first 500 miles, change oil to semi synth, up 500 revs at each 100 miles covered ( so upper rev limited to under 5000 rpm at 1000 miles, oil change to synth oil ) and on to 700 rpm by about 1500 miles. All this at miminum boost, about 7 psi max.

3000 miles oil change, fully synth ester oil, 10 psi boost allowed, 7500 rpm limit.

Not thrashed / run hard, no sustained hard runs or high speed runs.


How long does it take to bed in rings etc.?

Should there be much crankcase pressure / blowing out of oil cap? What is likely cause? Any damage?



Any comments welcome!

Bonzo

 

there should be some air blowing out of the filler cap yes.. if you put your hand on it and rev the engine you should feel a vacuum form.. shouldn't need mega revs for it to occur.

If there was a serious problem you would have oil out of the dipstick hole, filler cap and breathers..

Simon