Oil on intake???'s

[79 USA 1]

My take is the manifold gaskets wicking oil up through the bolt holes. Far fetched but when I've replaced the gaskets (Twice so far) the fastener holes are always filled with oil upon removal despite sealing the threads. This issue started with the last head rebuild, the guy who did them recommended having the intake "correction milled" to get a better seal due to the heads sitting slightly lower and farther out on the block. Last set of heads he will ever work on for me.
I'm just planning to replace the heads to go on this engine when it gets refreshed this year.
I'm following if someone else has also is having this issue. My younger brother has the same manifold in his 400 sbc and has no problems.

 

[dickeymoore]

Yeah I have been using these same intakes for years and never had a oil leak like this one.

 

[79 USA 1]

Did you have any work done to the heads other than a clean up/true up during a refresh?
The idea of casting porosity was mentioned to me but, that was ruled out due to the manifold staying dry before having the head work done. I had the manifold on the engine for two or three years prior with no problem.

 

[ELCAM]

If things have been milled you might find you need to use RTV for the front and rear valley gaskets instead if the gaskets provided. Also put sealer on the intake manifold bolt threads and put RTV on the bottom of the bolt heads lightly finger tighten them and clean off the excess, let the RTV set up and then torque the bolts.

 

[79 USA 1]

If things have been milled you might find you need to use RTV for the front and rear valley gaskets instead if the gaskets provided. Also put sealer on the intake manifold bolt threads and put RTV on the bottom of the bolt heads lightly finger tighten them and clean off the excess, let the RTV set up and then torque the bolts.

I've always used that method on the china walls at the front and back as well as sealing the threads with RTV. Again this problem reared its ugly head after crack repair that if the rebuilder would have questioned me about I would have NOT had performed. Smog 882 heads were plentiful at the time.

 

[ELCAM]

Where is the crack located?

 

[79 USA 1]

Between the steam hole and the head bolt between the center cylinders on both heads also same area on the between the next cylinder on one head.
In my eyes the heads were scrap but, the guy doing the valve job felt they could be repaired by a machine shop doing his clean up mill work. Don't get me wrong they hold pressure/water and have never overheated but this oil leak without a "witness mark" as to where it's coming from is frustrating.

 

[ELCAM]

Pull a manifold bolt and see if the RTV is still there? If not you need real thread sealer. Think later model stuff you take apart and the sealer is still on the bolt after a decade or more.

Thread sealers I have used:

Permatex 80632 or Form-A-Gasket No. 2 OR Loctite 1158514 or 1527514.

I think even Teflon tape would work better than RTV.

There are also sealing bolts with O-ring grooves cut in the bottom of the head pricey since they are for industrial stuff but they do work.

 

[dickeymoore]

I used the Permatex 80632 on the intake bolts

 

[ELCAM]

Above you said you sealed the bolts with RTV so I mentioned the other products.

Two ideas, pull some or all the manifold bolts and see if there is oil up at the head level, and with it fully warmed up see if there is pressure in the crankcase maybe one of those cracks is not sealed up and exhaust or compression gases are getting into the crankcase pressurizing it,