I'm chasing an oil leak on the rear of my 1974 small block (which is in my '62). I've replaced the oil pan and valve cover gaskets with the new super duper Fel-Pro gaskets. It doesn't seem to be a rear main gasket leak because there's no oil inside the bell housing. The oil leak seems to be on the right rear, just under the rear of the exhaust manifold and above the starter. Hard to tell. Can't see much back there. In previous posts, others have mentioned the possibility of plugs leaking on the back of the engine. My transmission is to replaced soon, and I will then have some access back there. I'd like to take that opportunity to button everything up back there. How do I do that? I'd like to order the parts before I lay the car up for the transmission job.
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Re: Rear of (Small)Block Oil Leak
Chris:
Did you check the rear of the intake manifold? Also, make sure that there is a paper gasket between the distribuor housing and the intake. It looks like you have looked high and low for this leak, but sometimes you have to back up a couple steps.
Joe -
Re: Rear of (Small)Block Oil Leak
Chris----
Your problem sounds more like it might be an intake manifold rear seal or a valve cover leak. Valve cover leaks can be very "insidious" with oil ending up just about anywhere below the valve covers. As Joe said, check your intake manifold rear seal for leakage and, also, check to be sure that the distributor gasket is in place as Joe also suggested.
As far as the block plugs go, if it's necessary to look into that, you don't need much in the way of parts. Once you get the transmission, clutch, and flywheel out, you will be able to inspect the rear of the block. Check the area below the 3 oil gallery pipe plugs which "surround" the top of the camshaft rear soft plug and the camshaft soft plug, itself. If there is leakage from one of these sources, it should be readily apparent. If so, the pipe plugs should be removed, cleaned, sealed with a non-hardening sealer, and re-installed.
The camshaft soft plug, if leaking, will need to be removed and replaced. These plugs are available in steel or brass at most auto parts stores. A GM replacement in steel is available under GM #3704158 for a current GM list of $1.45/each.In Appreciation of John HinckleyComment
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Re: Rear of (Small)Block Oil Leak
Here's one way I have used to find oil leaks. Plug one side of the PCV system, attach a hose to the other side and pressurize the system. You can rig a small pump, use your air compressor with a blow dry nozzle, or just blow into the hose. You only need about one to two psi (be careful not to over-pressurize.) The only leak path should be past the ring gaps. which you can usually hear, and you should be able to hear hissing from any gasket leaks, but you have to be close. Get under the car to check low and use the old hose in the hear "stethoscope" to check all the nooks and crannies.
DukeComment
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