blowing oil
Thread Starter
Racer
Joined: Feb 2005
Posts: 374
Likes: 4
From: decatur ga
blowing oil
I need some advise.
I have a 76 vette with a big block in it.I have started to have oil blowing out the valve cover breathers.I checked to compression and all are over 200.What could be the problem?
Thanks
I have a 76 vette with a big block in it.I have started to have oil blowing out the valve cover breathers.I checked to compression and all are over 200.What could be the problem?
Thanks
Pro
Joined: Feb 2012
Posts: 577
Likes: 6
Thread Starter
Racer
Joined: Feb 2005
Posts: 374
Likes: 4
From: decatur ga
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Do you have baffles in the valvecover under the PCV and breather holes? Many aftermarket covers have insufficiant or no baffling. High volume oil pumps compound the problem.
Pro
Joined: Feb 2012
Posts: 577
Likes: 6
Pull the PCV valve and shake it to see if it rattles. Can't hurt to squirt some brake cleaner through it to help clear out any gunk. Also pull the filter and inspect it as they tend to soak up oil quickly when there is a problem with the ventilation.
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Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
You need a complete PVC get rid of the breather and hook into the bottom or the side of the air cleaner like an OEM style.
Compression test is not as accurate as a Leak down test at TDC.
I have seen new builds with good compression but leak down up to 40%
Compression test is not as accurate as a Leak down test at TDC.
I have seen new builds with good compression but leak down up to 40%
Thread Starter
Racer
Joined: Feb 2005
Posts: 374
Likes: 4
From: decatur ga
oil
What is the correct way to do a leak down test? And what will it tell me
Heel & Toe
Joined: Jun 2004
Posts: 22
Likes: 0
From: Tucker GA
A leakdown test will give you comparative readings for each cylinder indicating the ability of the cylinder to "hold" compression. It's not a difficult test to perform but it does take some time.
Here is an article from Car Craft magazine
http://www.carcraft.com/techarticles...r/viewall.html
Here is an article from Car Craft magazine
http://www.carcraft.com/techarticles...r/viewall.html
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
when I fired up my BB, I had a problem of crankcase pressure building up and blowing oil out also,
finally found the aftermarket pvc gromment, was sealing up tight, not allowing the PCV to do its job. modiified the gromment to ensure it did not seal up closed, problem solved.
finally found the aftermarket pvc gromment, was sealing up tight, not allowing the PCV to do its job. modiified the gromment to ensure it did not seal up closed, problem solved.
