QuestionI have a 1959 Corvette that has been "frame off" restored but I have an oil leak that "appears" to be coming from the rear of the oil pan. How do I tell if it is the pan seal or the rear main seal? I don't want to rush to conclusions nut if it is a rear main what tricks/kits do you recommend for changing it w/o dropping the crank? The leak is about 6-8 drops over a weeks period.
AnswerHi, John:
Drain the pan well and let it sit overnight with no oil in it.
Remove all of the pan bolts and drop it straight down. Make sure your hands are clean and no oil is spilled anywhere, as you want to inspect the sealing surface at the rear main on both the lip of the pan and the recess in the rear main cap. Oil showing on either surface could be an indication of a leaky pan rear seal. If the surfaces are dry, it's the rear main (unlikely!).
Whether the rear main is the rope style or the elastomeric style ('the changeover was sometime in '59), there's a kit made to replace it without dropping the crank.
The rope seal kit will come with two pieces of seal material, a T-handled corkscrew type puller to pull out the old upper half, and a "Chinese handcuff" type of T-handled puller to install the new rope. You'll have to pull the coil wire and use a remote starter switch to rotate the engine to help pull the old upper seal half out, and the new upper seal half into its groove in the block.
Be sure the seal is trimmed properly (NOT flush with the cap, but protruding about 1/16" on each side; this provides the "crush"necessary to give a full circumferential seal.
The elastomeric seal is driven out with a punch or drift, and the new one pulled in with a similar tool included in the kit as well. I believe both kits are made by Lisle.
Either way, replacing the pan seals and rear main halves is about a 2 hour job and nothing to be hesitant about.
BTW, I always use "Form a Gasket" liquid (#3) and paste (#1)when fixing old Chevy pans; they didn't have silicone in those days...just call me old-fashioned!
--Paul
