Thread: 283 sbc

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I have a 1966 283 sbc in a Chevelle Malibu. It runs great, does not smoke, and has great compression. While I was replacing the old parts on the engine including: hei distributor, intake, carb, cam, lifters, push rods, rocker arms, and headers. Before I installed I started the car stock. No oil leaked from anywhere. I have a timing cover leak from the one I put on but I will shortly be replacing it. After I would drive the car and park after the parts were installed. I would notice a small puddle of oil. I was wondering if anyone knows what this could be? I don't know if it is the oil pan gasket or rear main seal. I honestly do not know. Any suggestions would be greatly appreciated.

Possibilities: If you used the original stamped steel oil pan, you could have tightened the pan bolts too tight compromised the gasket. What type of rear main seal did you use? Original rope type or 2-piece silicone?

First, welcome to CHR! Glad you're here, and looking forward to pictures of the Chevelle.

On your oil leak question, it's all but impossible to diagnose blind. Like Jack says, it's very, very easy to over tighten an oil pan and squeeze the gasket out from between pan & block. Also, the joint between the pan rails and the front & rear at the mains can be a nasty spot. I like the FelPro one piece blue rubber pan gaskets that come with the four plastic retainers to hold the pan & gasket in place while you take your time to put the other bolts in place. Cleanliness is critical with them - no residue, and clean all surfaces with solvent, like carb cleaner or brake cleaner spray.
You changed the intake, so another easy oil leak is the front or rear valley seal. I throw away the rubber or cork gaskets that come with the intake gasket set for the serpentines front & back, and after sticking the intake gasket to the heads using something like Gasgacinch I lay down a heavy bead of silicone, at least 1/4" OD and let it tack for about five minutes. Once tacky, set the intake down straight, zero lateral movement, and torque it into place. Alignment bolts at the corners of the intake help a bunch with dropping it down straight, with no jockeying for alignment.
The other one that's bit all of us at one time or another is simply missing a hole on a rocker cover gasket, or like the oil pan, getting too strong on the ratchet and squeezing the gasket out. It's amazing how much oil can leak out of a rocker cover when the gasket's not aligned.
Bottom line, if the car didn't leak oil before then it's all but certain that something you've done introduced the leak. I can't see how you would have suddenly developed a rear main seal leak with what you did. Backtrack and look at all of the places you had stuff off and/or loose.

Thanks both for the quick reply. The car was my grandmothers car with 116,000 miles on her. The oil pan hasn't been removed, nor has the rear main seal been replaced. The leak isn't coming from the intake, it's more below the intake, near the distributer. I always use gasketmaker, and I try to never overtighten. It's also not coming from the valve covers. It just leaks after running because when running the engine does not leak much at all. I can go 70 miles and it has barely if any moved on the dipstick. Thanks for the replys! Suggestions are ALWAYS Appreciated.
Thanks

Did you remember the dizzy gasket?

Originally Posted by firebird77clone

Did you remember the dizzy gasket?

Eureka! Good point. I got focused on the pan and rear main seal at the end of the post.

did the car sit for awhile - could the rear main seal have gone hard? did you drive it far before pulling it apart? is the puddle of oil black or red ? it may be the seal on the front of the auto
just a couple of things to think about
good luck , mark

I'd bet a nickel the leak is at the manifold/block interface at the rear china wall, especially if you used the black rubber seals. Most guys throw those over the fence and use a fat bead of RTV at the front and rear.

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"......Did you remember the dizzy gasket? ...."

Good catch on that Firebird. A word of caution on that gasket....do not use any sealer on it or the first time you set the timing will cause the gasket to rip.

As long as you're back there you probably want to take look at the oil pressure sending unit that is down by the base of the distributor. It's a part that's easy to bump when changing the intake and I've replaced several leaking ones over the years.


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There's bound to be a trail of oil from the source on the engine which you can see and we can't. But since we're playing a thousand guesses I'll jump in too.
Does this still have the canister style oil filter? When/if that was changed was the old O-ring removed before the new one installed? Common mistake back when was to leave the old one in because it didn't fall out, and two O-rings won't usually seal properly.

OR it could be a bad oil sending unit at the back of the block behind the distributor...

Originally Posted by Bob Parmenter

There's bound to be a trail of oil from the source on the engine which you can see and we can't. But since we're playing a thousand guesses I'll jump in too.
Does this still have the canister style oil filter? When/if that was changed was the old O-ring removed before the new one installed? Common mistake back when was to leave the old one in because it didn't fall out, and two O-rings won't usually seal properly.

In the Navy '68 lots of very young enlisted around, and everyone looking to save a nickel anywhere they could, for more beer money. One of the "tweet's" (electronics/radio/radar tech) changed his oil & filter on a bone stock '56 chevy, knew nothing of the gaskets and after filling it up took off immediately up towards the main gate, not realizing the trail of oil he was leaving, and wondering what that new noise was that he was hearing..... By the time he stopped the engine was toast, and he was looking for a new ride.

Sorry for the hijack - the old memory was just too strong to pass up.

I started playing a game when I go to the local car shows here in Tucson. The game is "find a Corvette that doesnt have a leaking oil pressure sender".....so far, 8 out of 10 have oil leaks back there. Clean the back side of the engine and find the leak with your fingers after you have driven it a bit.....you'll touch the fresh oil.

That reminds me of what a Navy AFCM at Oceana told me about F-14 Fighters, "If they aren't leaking, they're empty." I had a leaky oil pressure sensor on my '93 Vette.

Thanks for the replys first of all! It has been a ton of help. I think it may be the oil sending unit. I checked it and the bolt is loose. Also is there any particular way of checking if a car's posi is working? Sometimes it will engage and other times it will act like an open fear end.