Actually if it's an issue of sealing it's better to mill the intake surface of the head. That way if you are swapping intakes like the poster is doing they always remain stock, can be used on other builds and sold as a stock intake..
Oil on intake mating surface- is this normal?
- Thread starter Frankb
- Start date
Geoff 2
Well-Known Member
Sealing the intake bolts. You do not need a sealer on them, buuuuuuuuuut it is a good idea...
[1] The crankcase gets pressurised from blow by. After time, if the bolts do NOT have sealer on them, the oil will wick up the threads & leave a mess around the bolt heads. Loctite 567 is a good sealer.
[2] A bolt without sealer on it does NOT cause oil to be drawn into the intake port. Oil in the intake ports means that the gasket is not sealing.....
[1] The crankcase gets pressurised from blow by. After time, if the bolts do NOT have sealer on them, the oil will wick up the threads & leave a mess around the bolt heads. Loctite 567 is a good sealer.
[2] A bolt without sealer on it does NOT cause oil to be drawn into the intake port
BSB67
Well-Known Member
It is common for people to believe that oil collecting on the valley pan is from the bolts. It is not. Oil on the manifold is a different story.
I’ve probably R&R 100 BB Mopar intakes. Never had oil on the manifold. If crankcase pressure is the cause, why don’t they all leak? Why is using a sealer not in my four service manuals?
The simple physics of crankcase pressure potentially pushing (not wicking) oil out the top of the bolt/washer/manifold interface onto the intake manifold is sound, but the evidence suggest that if you do, you likely have something else going on.
I’ve probably R&R 100 BB Mopar intakes. Never had oil on the manifold. If crankcase pressure is the cause, why don’t they all leak? Why is using a sealer not in my four service manuals?
The simple physics of crankcase pressure potentially pushing (not wicking) oil out the top of the bolt/washer/manifold interface onto the intake manifold is sound, but the evidence suggest that if you do, you likely have something else going on.
Last edited:
Geoff 2
Well-Known Member
All engines have crankcase pressure. How much depends.....
I have seen dip sticks pushed up out of the tube because of excessive crankcase pressure...
Whether or not all of the intake bolts will develop oil residue over time will depend on the mating surfaces of the bolt head [ & washer if used ] & the intake surface.
I have seen dip sticks pushed up out of the tube because of excessive crankcase pressure...
Whether or not all of the intake bolts will develop oil residue over time will depend on the mating surfaces of the bolt head [ & washer if used ] & the intake surface.
Jonas Nordstrom
Well-Known Member
I once got oil in my tub under the intake...guess what, it was the bolts. Some sealer on and dry like a desert.
BSB67
Well-Known Member
Was there oil on the intake puddling under the bolts, and running down onto the pan?
Similar threads
