oil pan or rear seal

[jolobo64]

64 c 10 350 chevy small block ( mid 70's engine), I have checked all obvious areas for oil leak and I am sure its at the rear main seal or oil pan. Just not sure which one from the two. I had the rear main seal replaced before but maybe the guy didn't do it right or maybe he didn't seal the oil pan back right.

This time Ill do it myself, I have not dropped the pan yet but there is wet (oil) right at the front lip (curve) of the oil pan.I know either way it goes I have to drop the pan but I don't want to replace the rear main if no need and I also am trying not to just do the oil pan gasket and then see if it works and if good , good but if not then I have to drop it again and do them both.

Just wondering if there is a way to tell clearly between the two when I finally drop the pan.

[jjzepplin]

So your question is --- should I do this once or twice? I vote once!

[jolobo64]

Originally Posted by jjzepplin

So your question is --- should I do this once or twice? I vote once!

yea thats pretty much it!!!!! thanks buddy

[cg285]

dye and a black light is one way however in lieu of that clean it real good, dust talcum powder all around the area, run the engine and observe

[jolobo64]

Originally Posted by cg285

dye and a black light is one way however in lieu of that clean it real good, dust talcum powder all around the area, run the engine and observe

I have the light and dye but how can you tell if rear main seal without dropping the oil pan? thats impossible right?

[cg285]

follow the dye trail. if it doesn't come off the crank it's the pan. note: there is typically more of an oil leak with a rear seal vs pan
also i'm not a big user of sealants however the front and rear pan rubbers is one area i use sealant. between the pan and rubber only

[jolobo64]

A few questions for a layman like myself, I dropped the oil pan (well mostly because cross member will not allow full removal but its enough room to work).

I removed rear main seal and oil pan gasket(rear part was chewed a bit, this time I am going with the one piece type) but I am trying to understand something.


1st question, if the rear main seal is above the oil pan and oil pan is sealed properly how can the rear main seal leak?

2nd question when I removed the rear main seal, cap etc I noticed a small hole right in the centre of the I don't know what you call it I think crank, (see pics). Is that normal? I have seen others without it but its such a neat hole, I'm wondering why is it there and whats the difference between one with a hole and one without?

[cg285]

1. personally i wouldn't use a one piece gasket.
2. the rear main seals the crankshaft, not the pan. it would leak past the seal and gravity pulls it to the ground via the pan during it's adventure
3. re: hole - oh my! how do you reckon oil gets to the bearings? turn the crank 90 degrees and you will have a new one without the hole

[jolobo64]

Originally Posted by cg285

1. personally i wouldn't use a one piece gasket.
2. the rear main seals the crankshaft, not the pan. it would leak past the seal and gravity pulls it to the ground via the pan during it's adventure
3. re: hole - oh my! how do you reckon oil gets to the bearings? turn the crank 90 degrees and you will have a new one without the hole

Thanks my man all clear and I have tried the other oil pan gaskets( three pieces ) but like I said all chewed up so I figure let me try something new and I saw fair reviews so we see.

[cg285]

Originally Posted by jolobo64

Thanks my man all clear and I have tried the other oil pan gaskets( three pieces ) but like I said all chewed up so I figure let me try something new and I saw fair reviews so we see.

fwiw i have had a couple, in the shop, that had one piece gaskets and a tube or 2 of silicon goobered everywhere and still had substantial leaks. fixed with the original style 3 piece - but i'm set in my ways with what has always worked

[enaberif]

Rear main seal can leak because of 2 things..

1) They didn't clock the seal meaning that when you install it you want to turn the seal slightly so join isn't at the same join as the cap to block.

2) Not applying a small amount of RTV sealant to the crank block.