Intake Manifold - Oil Leak???

[Hokie93]

I've been cleaning up all the little leaks around my engine and I'm down to just two, and one I need help with. It's been a while since I've done much to a car on my own, so forgive me if this is a dumb question.

The leak looks to be coming from the top rear of the 302 in my 76, could it be coming from the intake manifold? While it looks like that's the case, my common sense says it can't be, there's just air and gas up there. If so, how many hours will that take the average do-it-yourselfer to replace?

PS: I just had the rear main seal done at the shop, so I don't think it's that.

 

[Wyflyer]

The intake gets oil splashed on it from below, from the lifter galley and push rods. Most of the time, if we were to pull our intake off it would not exactly be dripping with oil, but it would be oily just the same.

Rant & Rave alert:
I often recommend to people they check their PCV valve because it keeps it from building positive pressure and blowing oil out of every seal on the engine. The rings and valve guides lose some compression into the engine and if the PCV plugs up or the valve cover breather plugs up, the combination of heat and pressure will ruin seals, even new ones.

Sorry, i had to get that out of my system! Anyhow, it's not a big thing to change an intake, but i'd do a little snooping first. I'd wash it all down with solvent or brake cleaner, then run it and watch it and find out for certain where it's comiing from. I mean, the exact seal and the exact spot it's dripping.
Edit: Oh yeah, I forgot to answer your question about how long... If you haven't done one in awhile it could be an all day thing but shouldn't be longer than that. If you prepare well it should be a 3 or 4 hour task.

 

[ep67bro]

It sounds like the intake. It is a common leak spot where the intake meets the block. Like the post above said if the PVC valve is bad it can cause it to leak, an over tightened intake, or an old dried out gasket can be a cause. Some people just use RVT sealant and dont use a new gasket. I like to use a new gasket and a little RVT. I have done this with two small blocks and a big block with good luck. Time to do it should be a couple of hours if you got all the tools and gaskets ready. Make sure you use a torque wrench to tighten the bolts back down.

 

[broncnaz]

Very common especailly if the valley gasket was used. That area of the intake doesnt lead to the combustion chamber so its not air/fuel. Its basically open to the internal engine. To much blow by ie piston rings worn, bad PCV valve or just old gaskets will allow this leak. Shouldnt take more than 2-3 hours on a bronco to fix it. I've tried using the valley gaskets in the past but they seem to get squeezed out and start leaking again. Since I used RTV I've had fewer problems with leakage.

 

[justinoshea]

I had hell getting that leak fixed on a new engine. finally got it stopped by cleaning the block surface down to bare, fresh metal so the RTV would stick. No gasket, just a fat bead and let it dry a little before assembly. The TFS intake instruction said to toss the gasket too.