Oil leak under timing chain cover. NEED HELP!!!

[n8tivetigga]

I am currently restoring a 76 chevy 1/2 ton c10. It currently has a 350 5.7l small block and th350. I've replaced the oil gasket and it still leaked. Next I replaced the timing chain cover, installed a new gasket and leaked. Both atempts I used a 1 piece felpro gasket. Next I purchased a new oil pan and reinstalled a one piece gasket from lopers performance out of Mesa Az which fit more snug than the felpro one, but the leak continues. All atempts, matting surfaces were thourghly cleaned and degreased on engine block using brake parts cleaner, 1/4" bolts were torqued to 7 ft. lbs, 5/16" bolts were torqued to 17ft. lbs. I've noticed the the gap between timing chain cover and oil pan wasn't consistang around the whole radius, lower gap is about twice as wide as the wide looking straight at timing chain cover. I thought new oil pan would fix this but never changed. I'm ready to take the last resort and try a stop leak additive. So if any ones had the same drama and had sucess please hit me up. Keep on Truckin...

[cowboy33713]

Howdy- is the leak not coming from the harmonic balancer seal that is pressed into the timing case cover? if the seal is old or damaged, it will leak. If the sealing surface of the balancer ( where the seal contacts it) is worn enough- it will leak.
Small Chevies used two different seals at the bottom of the timing cover to seal against the oilpan, which one you need depends on the year of the engine.
Back when I had my '67, I discovered this when I had to replace it's timing chain set. The engine was A 350, a transplant ( no such thing as a 350 in 1967!). Fortunately, the gasket set I bought had both possible seals, one visibly fatter than the other.
Hope that helps.

[68 TT]

Originally Posted by cowboy33713

...Small Chevies used two different seals at the bottom of the timing cover to seal against the oilpan, which one you need depends on the year of the engine.
Back when I had my '67, I discovered this when I had to replace it's timing chain set. The engine was A 350, a transplant ( no such thing as a 350 in 1967!). Fortunately, the gasket set I bought had both possible seals, one visibly fatter than the other.
Hope that helps.

Actually there were 350's in 67 but only in Camaro's. First year and only in the SS. Not available in any other car even the Vette that year.

[68 TT]

Originally Posted by n8tivetigga

I am currently restoring a 76 chevy 1/2 ton c10. It currently has a 350 5.7l small block and th350. I've replaced the oil gasket and it still leaked. Next I replaced the timing chain cover, installed a new gasket and leaked. Both atempts I used a 1 piece felpro gasket. Next I purchased a new oil pan and reinstalled a one piece gasket from lopers performance out of Mesa Az which fit more snug than the felpro one, but the leak continues. All atempts, matting surfaces were thourghly cleaned and degreased on engine block using brake parts cleaner, 1/4" bolts were torqued to 7 ft. lbs, 5/16" bolts were torqued to 17ft. lbs. I've noticed the the gap between timing chain cover and oil pan wasn't consistang around the whole radius, lower gap is about twice as wide as the wide looking straight at timing chain cover. I thought new oil pan would fix this but never changed. I'm ready to take the last resort and try a stop leak additive. So if any ones had the same drama and had sucess please hit me up. Keep on Truckin...

Had the same problem when I first got my K20. It leaked even with the right end gasket on the pan and a decent amount of sealant on it. Didn't have the time to yank it back out so I just coated the gap with ultra black RTV. It stopped the leak.

I cleaned it up and did it right when I had to replace the clutch, just used a thicker bead of sealant on the front that I typically had in the past. I have built dozens of small blocks and never had one leak like that until this truck. No problem this time.

[powerdriver 1958]

Any way to get a picture of the gap.that sometimes helps

[n8tivetigga]

Originally Posted by cowboy33713

Howdy- is the leak not coming from the harmonic balancer seal that is pressed into the timing case cover? if the seal is old or damaged, it will leak. If the sealing surface of the balancer ( where the seal contacts it) is worn enough- it will leak.
Small Chevies used two different seals at the bottom of the timing cover to seal against the oilpan, which one you need depends on the year of the engine.
Back when I had my '67, I discovered this when I had to replace it's timing chain set. The engine was A 350, a transplant ( no such thing as a 350 in 1967!). Fortunately, the gasket set I bought had both possible seals, one visibly fatter than the other.
Hope that helps.

Thanks 4 the advise. I'm gonna make that my project 4 this weekend. It won't hurt to change it out anyways. I'll keep you posted.

[72-350]

I am experiencing similar problems. I have also searched multiple forums, most blame the quality of the chrome timing chain cover and have either gone oem replacement or caked on gasket sealer and had success. BUT! I believe cowboy33713 has it right. In most gasket sets or timing cover assemblies containing the gasket that fits between the oil pan and timing cover it is the wrong size. I bought two different brands of gasket sets for the timing cover as well the timing cover assembly with gaskets, and they were all TOO SMALL. I have also put a massive amount of gasket sealer which slowed the leak to a drip. I've just bought the oil pan gaskets which contain the front and rear seals. The front seal is considerably larger and of perfect fit. The front seal that came with the the oil pan gasket set will replace the ineffective gasket from the timing cover set. (Most timing covers come with rubber inserts on either side of this seal meant to sit on the corners of the oil pan) Once you have the new gasket you can remove those inserts, the new gasket will replace those as well. I am about to finish installment RIGHT NOW. Will let you know results. I also found this ------------------------------------------------------------------------------------
"There is a bolt hole that goes into the fuel pump pushrod hole that has to be sealed, if not you will have a leak just a FYI

But don't put too long of a bolt in there or you will run into the pushrod."--------"I have seen more small block Chevys with this Bolt missing. The owners do not understand why it is there. Looks like the bolt does nothing. So the bolt gets removed.

I think the bolt is 1/2 inch long 3/8 x 16 threads."
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[71maligreen]

use an aluminum timming chain cover and just use a dab of silicone on all 4 corners with the one piece oil pan gasket!! make sure all surfaces are clean and dry!! no more leaks