Freaky leak of oil in my 84..

[buddy84GMC]

I have an 84 GMC Sierra with a small block 400 in it.  I am having a problem with oil leaking from the oil breather cap which has been replaced with a oil cap with a filter in it.  Before that, I had added a PCV to it.  I thought this might help to relieve some of the oil pressure in the valve covers but it still comes out when under load.  It does not leak all the time except when I turn the truck off and of course press the gas.  Ant ideas on why this is happening?  The oil cap breather filter is completely filled with oil.  Oil coats that valve cover only and leaks down the side of the engine when I turn it off and only drips till the oil temp cools.  Thanks a lot.

[VileZambonie]

On one valve cover you should have a PCV valve. On the other valve cover you should have a breather. Is this how you are set up?

[Lt.Del]

Does the valve cover w/ the cap have a baffle?---piece of metal inside the cover just below the hole for the cap, that keeps oil from blowing up into the fill cap.

http://store.summitracing.com/egnsearch.asp?N=700+115+%2D152184&D=%2D152184

[buddy84GMC]

On one valve cover you should have a PCV valve. On the other valve cover you should have a breather. Is this how you are set up?

Yes, that is how its set up

[buddy84GMC]

Does the valve cover w/ the cap have a baffle?---piece of metal inside the cover just below the hole for the cap, that keeps oil from blowing up into the fill cap.

http://store.summitracing.com/egnsearch.asp?N=700+115+%2D152184&D=%2D152184

There was baffles on the old covers that were on the truck...these are cheap Edelbrock steel chrome ones from Advance and they do not have the baffle.  I am trying to think if the old covers leaked out the cap or not?  Cant remember.  Thanks and I did not even think of something that simple! 

[VileZambonie]

If your PCV valve is functioning and you have a breather on the other side then the baffle is your problem unless of course you have extreme blow by

[buddy84GMC]

If your PCV valve is functioning and you have a breather on the other side then the baffle is your problem unless of course you have extreme blow by

I thought it was a lot of blow by as well, but thats why I put the crankcase ventilation on it and the breather, though there is no baffle on these valve covers.  I could try that first unless 400s are known for a lot of blow by.  This is the only leak the truck has and its drivin me nuts!  I could always use the old valve cover and run it with that...this luckily is the good valve cover, the other one was installed 180 degrees the wrong way by the previous owner, but I never turned it back since I did not hear any knocking...but the rocker slowly ate the aluminum valve cover away till it cracked when under pressure!  That had to of course happen on a 2 and half hour road trip back to college...turned into a 10 and half hour trip!  Thanks guys..let me know if high extreme blow by is normal for a small block 400?

[VileZambonie]

blowby is the result of poor sealing piston rings. If you pull out the dipstick while it's running do you feel pressure over the dipstick tube? Odds are it's probably just your cheap unbaffled vc's

[buddy84GMC]

Thanks a lot for the help.  Iwill have to throw the old one on and see.  Take care