Oil in intake and head intake passages

[Jack O.]

Re: Oil in intake and head intake passages

Joe,
I cleaned everything up and fitted the intake, without gaskets, to the heads. Everything appears to fit good except that there is ~3/16" gap front and back. Is this acceptable considering that the gasket set usually comes with fairly thick rubber end gaskets? Also, the bolts line up nicely and can be started by hand.
Maybe I'm barking up the wrong tree. Most the posts about this problem indicate high oil consumption and blue smoke neither of which I have. My plugs burn pretty clean also. How did you check that you had or had not corrected your problem? Did you notice continued high oil consumption or did you actually pull the intake and look? I believe I'd have to do the later. Does correct PCV operation involve more than simply ensuring their is sufficient vacum to the valve and that the valve is working correctly? Thanks again for all help!
Jack

[Joe L.]

Re: Oil in intake and head intake passages

Joe,
I cleaned everything up and fitted the intake, without gaskets, to the heads. Everything appears to fit good except that there is ~3/16" gap front and back. Is this acceptable considering that the gasket set usually comes with fairly thick rubber end gaskets? Also, the bolts line up nicely and can be started by hand.
Maybe I'm barking up the wrong tree. Most the posts about this problem indicate high oil consumption and blue smoke neither of which I have. My plugs burn pretty clean also. How did you check that you had or had not corrected your problem? Did you notice continued high oil consumption or did you actually pull the intake and look? I believe I'd have to do the later. Does correct PCV operation involve more than simply ensuring their is sufficient vacum to the valve and that the valve is working correctly? Thanks again for all help!
Jack

Jack-----


High oil consumption (1 quart in 300-500 miles) and smoking were always the "signal" to me that the problem had not been corrected. Removing the intake manifold and visual inspection always revealed the same thing.

3/16" gap at the manifold ends should be enough. However, if the gasket get's "squeezed out", that's another sign of a problem. Machining the manifold end surfaces is only a "band-aid"; it does not solve the underlying problem. You can also just use silicone RTV instead of the end seals. This seals better.

PCV operation basically just involves making sure hoses are in good shape, valve is clean and the proper one, vacuum is as it should be, AND that valve cover oil baffles are present.

[Robert M.]

Re: Oil in intake and head intake passages

Hi everyone,
I pulled my intake manifold ('69 427/435 but I'm running an LS6 intake) and have found oil in the intake as well as in the intake passages of the heads.

When you say you see oil in the intake, do you mean directly beneath the carb? Is it present in all runners or just a few?

If the oil is directly under the carb wouldn't that indicate a problem with the pcv sucking oil up from the rocker covers, possibly due to a build up of oil or a blockage preventing it from draining back to the crankcase?