Leaking intake on a small block
 

I have just 27,000 miles on the El Camino since I did the new crate engine. The intake manifold is leaking oil. It is a decent leak and I can't ignore it.

I am pretty sure I used the Felpro brand of rubber gaskets. One friend says he prefers no gasket, just the black silicone sealant.

I will replace the intake and valve cover gaskets on Sunday. What would you recommend to use?

oil puddling right around the bolts? Or you mean leaking out the front between intake manifold and block?

on the bolts-black permatex RTV is what I use- cover the first 1/4" of the bolt and torque alternating, starting center of manifold working outward. snug, not too much torque.

on the manifold front and rear don't use a gasket- it will blow and leak-your friend is correct. run a 1/4" bead with a nice fat dab at the ends where the head and block meet, with same black permatex RTV, let it set for a few minutes then set manifold down.

PS if you use exhaust manifolds and not headers, don't bother with gaskets there- go iron to iron. The factory had no gaskets on exhaust manifolds, you don't need them.

Don't forget the distributor gasket..

rjp

If I'm correct you are referring to oil leaking between the intake manifold and the block where they meet to seal the lifter valley. Remove the intake and use a good high temp RTV where the rubber / cork gaskets would normally go; BTW I do not think GM has used rubber / cork at that area.

You might also check to make sure the PCV system is working correctly both on the low (vacuum) side and the high (breather) side. Also poor compression ring seal will contribute to high crankcase pressure.

Thanks guys.

The PVC system seems to be fine and crankcase pressure is normal. The old worn engine had high pressure and the oil filler cap was always oozing. The new engine is fine except the darn leaking intake manifold. The leak is on the front of the engine and the rear of the engine. It is just a messy oil leak.

Thanks for the reminder for the distributor gasket!

What about the valve cover gaskets? I have heard good things about the metal lined rubber gaskets from Felpro. Should I use cork or the Felpro gaskets?

Felpro- cork sucks.

You sure they are bad? The GM ones last a while...

Yep. do not use the end seals that come with the intake manifold gasket set. Just a nice thick bead of rtv, and carefully set the manifold on as straight down as possible. I try not to have to slide it very much , if any once it is set in place. I usually hand tighten all the bolts, and let the rtv cure for a little bit before I go to final torque.

The crate engine did not come with an intake. I installed an Eddelbrock intake that fit my throttle body fuel injection system. I am pretty sure I used the gasket set that came the the manifold. It was rubber and the pieces on the end are very soft now. It is like the oil and heat turned them to jelly. I just wish I knew then to not use the end pieces and just to use silicone.

it's that "corner" between the front of the block and the heads that get me.

Ooh- I mean the Valve cover gaskets- they are better these days... The manifold end gaskets, not so much

The one piece felpro intake gasket is much more reliable, but a ***** to install

THIS.

And set it down perfectly straight.

It's NBD, it's a 350, not a flat-6 :D

9/10 times I do a project on my SC, I'm wishing it was my old LS engine, so much easier.

After a full day in the garage the intake has been R&R and I am almost done. My back gave out before I could finish buttoning everything up.

Another secret no one shared: the distributor will rotate the oil pump as you pull the distributor. There is no way to get the distributor right back down where it came out. You have to jump up on the fender and almost mate with the car to peek down into the distributor hole and rotate the oil pump counterclockwise and GUESS how far to rotate it to get the distributor back down. It will take a few tries if you have never done it before. Then you need to use that funny looking distributor bolt wrench that most old time mechanics have in the toolbox. What a stupid design. It is a good thing they have not built many small block Chevy motors.

If any of you need me to re-seal your intake on a SCB engine just bring it by my house. I charge $9,000 plus parts cash up front. As soon as my assistant Bigfoot that rides the Unicorn shows up we will get started on it.

Actually what is happening when you pull the distributor out is the drive gear on the cam is twisting the distributor shaft as the gears de-mate (they're helical). If you watched as you took it out and noted it's location, you could have started with the rotor pointing in the same direction as it was once it was removed and it would have slipped right in, no muss no fuss.