greghennings

Hello, I purchased a 76 corvette a month or so ago and i'm going to start doing some projects on it, thought i'd find a forum for some help, so i'm just kind of testing the waters here.

Now, i'm mechanically inclined, i'm good with tools. But I've got a lot to learn yet about this corvette. This will be my first project car so take it easy on me if i sound like an idiot .

Now I've got a question that's probably unanswerable without being here to look at it, but I've got an oil leak that seems to be coming from between the engine and transmission. It appears to be dripping out the little hole at the bottom of the flywheel shield. Problem is from driving the car around, there's oil on everything.

Without tearing to much apart right now, I've removed the flywheel shield to get a better look, but my headers are in the way and i can't get the shield fully off. But what i can say is the flywheel is total void of oil despite everything around being covered in it.

I didn't know if there was a typical seal or gasket on the rear of these engines that cause problems or not is really what i'm asking. i was thinking like a seal for the crankshaft but if there's no oil on the flywheel well....

Now also, i bought the car and there were no oil leaks under it, even after being test drove the night before. But at the time i bought it, i noticed my oil pressure gauge was around 40-45. But something changed one day and it jumped to 75-80. Now, everyone I've talked to say more pressure is better, but i'm curious, would this increase in pressure be forcing oil out of a seal or gasket? And why the jump? Or why was it low to start?

Next spring i plan to have the car repainted, so if i have to pull the engine out to fix something now would be the time i suppose.

Thanks!

A88FXRS

rear main seal around crank could be the problem. also rear cam plug or galley plugs above crank could be leaking. oil pressure can not increase by itself. either faulty gauge or sender, do not believe a 76 is the old mechanical type setup.

vetteguy22

From what you say, it sounds like when you pulled the flywheel inspection cover, the flywheel and that area is void of oil? If so the the rear main seal is not at fault. The intake manifold at the back or maybe the valve cover gaskets could be leaking. Only way to know for sure is to completely clean the engine, then track where it is coming from.
As far as the oil pressure, you could install a temporary mechanical gauge to test the actual pressure, then go from there.

dgood

Also check around your distributor to see if it is leaking from there.

greghennings

hey thanks guys. Yeah its sort of hard to pinpoint the leak right now, the inspection plate on the flywheel is covered in oil, the surrounding area is oiled, but the actual flywheel itself it dry and a little rusty.

It only leaks for a while after being driven, it doesn't continue to leak day after day if that helps any.

I will try to take a closer look at the areas you guys described tomorrow, i can round up an oil pressure gauge too.

Vette5.5

Easiest way I know of to trace a leak, is putting some UV trace dye in the oil, and later scanning around with a UV light. You can now get a 40 led UV flashlight online, for about $20 bucks. You can get different colors of the dye for cooling, A/C systems, ext.

worship79

Did you check the pan bolts?

gcusmano74

The rear main seal on an old SBC is a bit notorious for leaking. The newer cars have an improved seal design. The only cure is to take everything apart down there and replace it. Very time consuming and expensive.
Sometimes an oil filter gasket will leak.
If it's not too bad, just put a piece of cardboard on the floor under it. Change it once a month. Done.

drwet

Check your oil pressure sender. Its located at the top of the block just to the left (drivers side) of the distributor. Mine failed a couple of years ago and drove me nuts looking for the oil leak. By the time I found it I was losing half a quart a week. The body of the oil pressure sender cracked and the leak kept getting worse. The oil ended up just about exactly where you described.

greghennings

i've gotten to the solution of my problem, set my aim on the rear seal. Pulled it apart, sure enough, your supposed to put some RTV compound between the cap and the block to finish off the seal. That was never done. Got a new seal and some dope to put on it and a way we go.

New question though, in my surfing around about this problem, i read something about priming the oil pump once reinstalled. Whats the procedure for that or is it even necessary?

Thanks!

TimAT

Not really necessary for an engine that has been running. IF you replaced the oil pump then I'd say yes. The original pump will have enough oil in it that it'll pickup immediatly so no issue. All the engine oil galleys will still have oil in them too.

RTV between the cap and the block is not the best idea. THe RTV is too thick to squeeze out and may not allow the cap to seat correctly. That's why GM originally didn't use RTV in there.

greghennings

Thanks Tim, i tried to follow the instructions you left in a previous thread actually i found here...

http://forums.corvetteforum.com/c3-t...-qestions.html

i suspect that maybe i read the post wrong, i found a similar posting on another website and they said to do the same thing here...except you can see by the picture they messed a little and put rtv on the seal itself, which they edited the correction not to.

http://www.corvettehacks.com/article5.html