Oil Pool in Top Recess on Intake Manifold

[Thomas S.]

Stock 63 / 327 / 340 SHP.

I have a strange situation whereby after driving, I get small pool of clean engine oil in a recess / valley on the intake manifold. I was told that this could be from a worn throttle shaft and that it could be the residue left over from a slight gas leak. There was never any residue on the bottom of the Carb or any of the shafts, nothing on the PCV or vacuum hoses and nothing directly next to the gasket area were the valve cover meets the head. Since I was having the carb restored anyway I wasn't concerned.

With the newly restored carb (shafts re-bushed) I was surprised to still see the same pool of clean engine oil whenever I finished a ride. There is still no obvious source for this oil and if the car is left idling for a while no residue appears. Anyway, even if the gasket was suspect, the oil would have to flow up and over the casting to end up in that recess. I also can't see how oil from below the manifold could get pass the manifold bolt adjacent to where the oil pools. Before I go the ultra-violet dye route, I though I would check in with the membership.

Any clues on this.

[Joe L.]

Re: Oil Pool in Top Recess on Intake Manifold

Stock 63 / 327 / 340 SHP.

I have a strange situation whereby after driving, I get small pool of clean engine oil in a recess / valley on the intake manifold. I was told that this could be from a worn throttle shaft and that it could be the residue left over from a slight gas leak. There was never any residue on the bottom of the Carb or any of the shafts, nothing on the PCV or vacuum hoses and nothing directly next to the gasket area were the valve cover meets the head. Since I was having the carb restored anyway I wasn't concerned.

With the newly restored carb (shafts re-bushed) I was surprised to still see the same pool of clean engine oil whenever I finished a ride. There is still no obvious source for this oil and if the car is left idling for a while no residue appears. Anyway, even if the gasket was suspect, the oil would have to flow up and over the casting to end up in that recess. I also can't see how oil from below the manifold could get pass the manifold bolt adjacent to where the oil pools. Before I go the ultra-violet dye route, I though I would check in with the membership.

Any clues on this.

Thomas-----


This is an age-old problem with Chevrolet V-8 engines. It is caused by oil "wicking-up" through the threads of intake manifold bolts that go through to the lifter valley. The way to correct it is to remove the bolts that go through to the lifter valley. Next, scrupulously clean both the bolts and the tappings in the head.and apply high temperature sealant to the threads. Re-install and torque to spec.

[Thomas S.]

Re: Oil Pool in Top Recess on Intake Manifold

Thomas-----


This is an age-old problem with Chevrolet V-8 engines. It is caused by oil "wicking-up" through the threads of intake manifold bolts that go through to the lifter valley. The way to correct it is to remove the bolts that go through to the lifter valley. Next, scrupulously clean both the bolts and the tappings in the head.and apply high temperature sealant to the threads. Re-install and torque to spec.

Thanks for the fast reply. I suspected that bolt but didn't realize this was a common issue. I guess I should be glad it's only one of them!

Thanks

[Mark E.]

Re: Oil Pool in Top Recess on Intake Manifold

Thomas,

No worries, this isn't a serious problem. Whoever installed the intake just didn't seal the threads of the bolts which go through to the lifter valley. Either they weren't experienced with assembling Chevy V8s or didn't care.

[William F.]

Re: Oil Pool in Top Recess on Intake Manifold

High Temp Ultrablack silicone gasket maker on threads worked best for me.

[Noel B.]

Re: Oil Pool in Top Recess on Intake Manifold

I had the same issue. I removed the manifold bolt, cleaned it and put sealant on the threads. Reinstalled and no more oil pool.

[Gene M.]

Re: Oil Pool in Top Recess on Intake Manifold

A jar of teflon seal works wonders on threads that wick up oil.

[William F.]

Re: Oil Pool in Top Recess on Intake Manifold

A "jar"?? Same as a tube of Teflon sealer or something different?

[Ed S.]

Re: Oil Pool in Top Recess on Intake Manifold

I am going to resurrect this thread for further discussion. I had the same problem with my all stock 64 L76. Six months ago it was a bolt near the # 1 cylinder. I pulled the bolt, cleaned the male & female threads, applied high temp thread sealer - problem solved. A few days ago it was a bolt above the # 2 cylinder. Here is the strange part. The recent pooling of oil (above # 2) developed after the engine sat and did not run for 3 or 4 days. When I first noticed the small pool of oil I cleaned it up. Did not start the engine - 24 hours later, puddle was back. The explanation for the formation of these puddles is that the oil "wicks up" the threads. How in the hell does oil flow up? Is Rotella also anti-gravitational? The source of the oil is not under pressure - based on everything I know about physics fluids do not flow up hill. Can anyone explain how this happens or...... do I have a more serious problem to investigate?

[Rich G.]

Re: Oil Pool in Top Recess on Intake Manifold

Maybe not the same thing, but in my airplanes engines when sitting the oil will wick UP the dip stick making the reading higher than it really is. Wiping the dipstick and re checking shows about a half quart lower.

I have no idea why this happens.

Rich.

[Thomas S.]

[Ed S.]

Re: Oil Pool in Top Recess on Intake Manifold


Capillary Action: Sometimes capillarity, capillary motion, capillary effect, or wicking, is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper and plaster, in some non-porous materials such as sand and liquefied carbon fiber, or in a biological cell. It occurs because of intermolecular forces between the liquid and surrounding solid surfaces. If the diameter of the tube is sufficiently small, then the combination of surface tension (which is caused by cohesion within the liquid) and adhesive forces between the liquid and container wall act to propel the liquid.

Thomas - thank you!

[Christopher R.]

Re: Oil Pool in Top Recess on Intake Manifold

i had the same issue on my 72 L48. Thanks for the advice on this one because I could not think where it was coming from but now I do and will fix that this weekend!!

[James N.]

Re: Oil Pool in Top Recess on Intake Manifold

What is the best practice for cleaning the female threads in the manifold when it's installed?

[Ed S.]

Re: Oil Pool in Top Recess on Intake Manifold

I use Q-tips, dip one end in acetone, hold the other end with a pair of needle nose pliers and just swirl the wet end around in the hole against the threads. I did 5 or 6 Q-tips before the last one came out clean.