383 valley pan

[Ray70Chrg]

Just pulled Carter afb carb to rebuild it. Also the intake manifold to clean it up and reseal it. The valley pan had lots of oily matter towards the rear portion. Is it common to find a oily mess there? I took it all apart also to reseal. There were no gaskets at all, just rtv crap. 1st time doing this and thought valley pan would be fairly clean if everything was sealed properly. Will replace valley pan so heat riser will be blocked. It is practically a solid block of carbon anyway.

 

[Kern Dog]

The intake manifold bolts need sealant. They thread directly into the lifter valley with oil splashing around and crankcase pressure. Oil will migrate up from the threads and rest on top of the valley.
The factory just put the valley pans on without gaskets. I use them since I have aluminum heads. I'd suggest using thin gaskets for any engine.

 

[BSB67]

KD, or someone, can you explain the exact path that the oil takes to end up in the belly of the intake pan? Are the heads of the intake bolts also swimming in oil?

I've probably R&R'd 50 intakes, and don't ever recall this happening, and have never used a thread sealant.

 

[Darter6]

Hard to believe but true. I call it oil wicking.Happens on small blocks too.A touch of thread sealant is all they need.

 

[1967coronet]

I have seen it also, for what ever reason oil will run/wick uphill. No pressure in the valley but oil will run up the bolt threads and onto a pan.

 

[Don Frelier]

I just use a very thin film of black RTV.
I wouldn't call it crap it's a very good sealant used correctly.

 

[BSB67]

But how does it get to the pan? If it does not come up through the head of the bolt to the top of the intake manifold first, it can only get there by means of a leaking intake gasket/pan. And guess what else is leaking if that is the case.

I think you fix the leaking intake gasket.

A bolt will not wick anything, but there can be pressure in the motor.

 

[Ray70Chrg]

Thanks to all for your relies. Actually the the bolt holes were full of sealant and it was a bit of a job getting it completely out. the rest of the sealing process was questionable since no gaskets were used at all. Hopefully I'll be able to seal it better. Some of the bolt heads were oily on the right side middle. I think that's the area where some of the oil was getting past the assembled parts. And yes this whole adventure was started because of very low manifold vacuum. I'll also add that all bolts were tight including 3 each on the valley pan end hold down metal strips.

 

[cheeseburgerhead69]

The bars at each end of the valley pan can leak if you don't get rtv applied to the corners well enough. Make sure to tighten the 3 bolts on the front and back evenly. Put a bit more sealer at the corners between the valley pan and the cylinder head. There are no gaskets for the valley pan on a big block, just the small blocks have seals at front and back.

 

[Demonic]

Check the aftermarket intakes against the head, sometimes the machining is off. Indy or someone had a procedure on the web about checking crust with wax string or Plastigauge.

 

[Daves69]

Don't overlook a possible crack in the pan bottom itself due to blow-by pressure making it flex constantly.

 

[Durandal25]

Surface tension will draw the oil up a little each time, and the crankcase pressure will cause it to push past the threads. #2 sealer works perfectly

 

[Kern Dog]

KD, or someone, can you explain the exact path that the oil takes to end up in the belly of the intake pan? Are the heads of the intake bolts also swimming in oil?

I've probably R&R'd 50 intakes, and don't ever recall this happening, and have never used a thread sealant.

Crankcase pressure, right? Blowby? No matter how tight the bolts are, there is still some clearance between the threads of the bolt and the threads of the heads. Oil vapor can leak out and reform as a liquid.

 

[1967coronet]

But how does it get to the pan? If it does not come up through the head of the bolt to the top of the intake manifold first, it can only get there by means of a leaking intake gasket/pan. And guess what else is leaking if that is the case.

I think you fix the leaking intake gasket.

A bolt will not wick anything, but there can be pressure in the motor.

Guess it could be lack of or faulty PCV. Valve. Could be intake leak . But like the op I have seen oil laying on top of the valley pan with no good reason for it to be there.

 

[BSB67]

Crankcase pressure, right? Blowby? No matter how tight the bolts are, there is still some clearance between the threads of the bolt and the threads of the heads. Oil vapor can leak out and reform as a liquid.

You are totally missing my point. Read carefully.

 

[BSB67]

Guess it could be lack of or faulty PCV. Valve. Could be intake leak . But like the op I have seen oil laying on top of the valley pan with no good reason for it to be there.

Even with a properly functioning PCV, there will be a slight positive pressure in the motor. But as mentioned, that still does not explain why it shows up in the pan

 

[Kern Dog]

You are totally missing my point. Read carefully.

Don't take this tactic with me. If you think you have a legitimate point, restate it.
The FSM states to use a sealant for this very reason. Oil vapor travels up through the intake mounting holes. I've seen oil puddles in the valley pan and the underside of the intake wet.Rick Ehrenberg wrote of this a few times as well.

 

[BSB67]

Okay. I'll write more slowly then. The bolt hole, and bolt threads are not "sealed", as mentioned several times, and can transfer oil - I agree. The oil travels up the bolt threads/bolt hole. Okay. But, how does it get from the bolt hole to the outside of the pan, if it does not come out at the bolt head. Only one way. It leaks between the intake surface/pan gasket/head. This is suppose to be an air tight seal to at least 20 in of Hg. But if it leaks oil and ambient pressure it cannot be sealed.

If you put sealant on your bolt threads to fix the oil issue, you are putting a band-aid on the symptom, not the problem.