Oil leak(s) - Pontiac GTO Forum
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post #1 of 4 (permalink) Old 12-28-2017, 11:10 AM Thread Starter
 
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Oil leak(s)

I have a few oil leaks on my project and would LOVE some help pinpointing the common problem areas.

One of the areas that has me baffled is towards the back of the engine - flat area near the distributor. Do the valley pans leak oil ?

Thanks in advance for your help!

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #2 of 4 (permalink) Old 12-28-2017, 12:41 PM
 
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Valley pans seldom leak oil from the gaskets. Since your engine has a tripower intake on it, I'd bet the PCV grommet which mounts in valley pan in the rearward position, I bet it's seen better days. I've always used Permeatex ultacopper or ultra black when installing the PCV grommets to the valley pans.
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post #3 of 4 (permalink) Old 12-29-2017, 08:10 AM Thread Starter
 
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Originally Posted by Pinion head View Post
Valley pans seldom leak oil from the gaskets. Since your engine has a tripower intake on it, I'd bet the PCV grommet which mounts in valley pan in the rearward position, I bet it's seen better days. I've always used Permeatex ultacopper or ultra black when installing the PCV grommets to the valley pans.
PH - Thanks but my PCV is in the front of the engine. I did replace the PCV and grommet, so I don't believe it is that.

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #4 of 4 (permalink) Old 12-31-2017, 10:51 AM
 
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Quote:
Originally Posted by cij911 View Post
I have a few oil leaks on my project and would LOVE some help pinpointing the common problem areas.

One of the areas that has me baffled is towards the back of the engine - flat area near the distributor. Do the valley pans leak oil ?

Thanks in advance for your help!
PH is correct, valley covers seldom leak if properly installed - so it could be the valley pan. Over torquing the hold down bolts can distort the pan and cause a leak. Aftermarket valley pan gasket too thin allowing oil to seep out. Valley pan gasket was improperly fitted when replaced. Distorted or damaged valley pan. Sometimes when a block has been "zero-decked" the valley pan needs to be trimmed/adjusted to the change in block height/angle created by the block milling - it will be seated incorrectly as the mating surface will be narrowed and the pan too wide and can cause a gasket leak.

The distributor could be leaking oil around the base where it fits into the block. There is a thin gasket that goes between the block & base of the distrib. and would require removal - but I have never had issues without using one so this is a long shot.

There is a plug near the distrib. base which is an oil galley plug. It can be removed and used to plumb an oil pressure gauge into. It is possible the plug may be slightly loose or not seated enough if it was ever removed for engine rebuilding or used for an oil gauge. Check this.

Valve cover gasket or valve cover not seated or loose. An engine builds pressure/blow-by at higher RPM's and it can pressurize the entire engine and literally push/blow oil out of any weak areas - like seeping out through a dried up/shrunked valve cover gasket or lift the valve cover enough to push oil if it is warped or loose (or even the valley pan). Must have valve cover breathers.

Make sure it is not something as simple as when you added oil some of it ran down the valve cover and drained down along the cover's edge and deposited itself on the block area near the distrib.

I have seen in the auto parts stores a kit having a dye and black light used to find oil leaks (or water leaks) which can be stubborn. Have never used one of these, but would if needed as they seem it would be a time saver if all else failed.
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