Excessive vacuum in crank case?

[Minstadave]

I've been getting awful MPG recently and have noticed that if I remove my oil filter cap whilst idling the cap is hard to remove, once I get it off the engine is sucking air in via the oil filter cap and the revs rise.

Is this normal? I think I may have a knackered PCV valve. Is it a DIY replacement job?

 

[Minstadave]

Anyone know if it's normal for the 2.0T to suck air through the dipstick and oil cap at idle?

 

[OVRA3]

If I take mine off or pull the dip stick I the car runns rough and tries to stall... Is that what you mean?

 

[MrLapou]

sounds normal to me with filler cap off.

 

[Minstadave]

sounds normal to me...

When I take the oil cap or dipstick out it starts sucking loads of air in and the revs rise. It's meant to run rough normally.

 

[OVRA3]

When I take the oil cap or dipstick out it starts sucking loads of air in and the revs rise. It's meant to run rough normally.

Dont think so mate, when you take off the cap it should shudder and struggle... Sure someone who knows more will be along soon

 

[RobinA3]

Yes there should be a vacuum inside the engine. The crankcase pressure should always be negative so when you remove the filler cap or dipstick when the engine running it will run like a sack of **** as unmetered air (air which is not measured by the airflow meter) is entering the engine.

 

[wuta3]

I've been getting awful MPG recently and have noticed that if I remove my oil filter cap whilst idling the cap is hard to remove, once I get it off the engine is sucking air in via the oil filter cap and the revs rise.

Is this normal? I think I may have a knackered PCV valve. Is it a DIY replacement job?

I had a rough idle, with reeealllyyy hard to remove oil cap etc and it was the PCV. It's an easy job on your drive. I gave the tubes a good clean too because they were caked in crap.

 

[becks2012]

Yes you require a new PCV valve the oil filler cap should not be that difficult to remove when engine on idle 5 min job