air blowing out of valve cover.

[obx tsi]

Is this normal? Never noticed this before, but when the car is running if you remove the oil cap you can feel air blowing out from there. Thanks.

 

[hereitcomes]

Well, the engine is pressureized and it creates vaccum. There should be a bit of oil flying out as well if you took the oil cap off.

 

[obx tsi]

Yes it did have oil coming out. I quess with all of the boost leaks maybe it just was not as noticable before. Thanks, I am just so paranoid with this car after my flywheel blew apart on the last one.

 

[Rahdigga8188]

I never noticed this either, because I never had air coming out of my crankcase vent tube. But then i fount a crack in my VC, swapped them, and BAM air out the breather!

 

[atlguyinbama]

Deffinitely check compression. I had a similar problem with having a pressurized valve cover, and low-and-behold, cracked #4 piston. Excess pressur in the crankcase is either from a bad PCV, or blowbye. Change the PCV, and do a compression test.

 

[Oneavenger]

Yes it did have oil coming out. I quess with all of the boost leaks maybe it just was not as noticable before. Thanks, I am just so paranoid with this car after my flywheel blew apart on the last one.

jesus, i've seen a crank fall apart before.

 

[LordDigi]

... either from a bad PCV, or blowbye. Change the PCV, and do a compression test.

After checking the PCV for proper functionality, like atlguyinbama said, do a compression test. Unless something is seriously wrong the compression test should come up just about normal. One thing that would help you out thought would be a leak down test. This test would pin point the leak within the engine allowing you to distinguish where is it coming from ... In this particular case I would assume that the leak is your valve seals allowing some compression from the cylinder to come up through the head and into the valve cover.

http://www.dsmgrrrl.com/FAQs/compression.htm

I do want to make it clear that there will always be a little air/pressure within the valve cover. To check this simply take the oil fill cap off and place your hand over the hole with the engine running. If you can feel the pressure building underneath your hand, then you have blow-by (this is assuming that you replaced or have a working PCV and no obstructions in those lines). Again, this blow-by can be verified by performing a leak down test; take the link below to learn how to do this.

http://www.dsmgrrrl.com/FAQs/leakdown.htm

 

[obx tsi]

Thanks for the replies. I will see what i come up with soon.