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Valve cover gasket

763 views 3 replies 4 participants last post by  Nubby55 
#1 ·
It seems I have a oil leak at the valve cover. The PO had installed a new one and had no issues. Can excessive pressure build up in the valve cover cause this. I have been getting blow back. It's a '89 4.2 auto. What would cause the pressure build up?
 
#2 ·
You state you have blow back (blowby). Is the valve cover leak the only symptom? Is it a cork VC gasket? Have you tightened the fasteners?
To start, run a compression check, dry and wet.
Another thing to check is how is the emission system plumbed. Is the PCV valve functioning. Do you have a vacuum gauge?
We need more info in order to be able to help.
Good Luck, L.M.
 
#3 ·
Yeah, what LM has suggested.

You need to determine if you have wear/damage that is creating excessive crankcase pressure. That's what the compression test will show.
If you are good there, then you need to service components your PCV system to fix any cracks, leaks, or blockages that are preventing the system from maintaining a slight vacuum in the crankcase.

https://www.youtube.com/watch?v=PDkCbJOV-28
 
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