Leaking near flywheel

[Praxiss454]

I've noticed a few puddles of oil under my truck lately, and so I finally get under there to look around. This may be a really stupid question, but am I supposed to be able to see my flywheel like this? This *seems* like the origin of my oil leak.

I guess maybe it's leaking from the oil pan gasket or elsewhere and just blowing back to this spot but this just doesn't seem right to me.

[61_FL_Apache]

What engine and trans do you have? that's usually covered up by an inspection cover.

[Praxiss454]

Originally Posted by 61_FL_Apache

What engine and trans do you have? that's usually covered up by an inspection cover.

It is the L6 230 engine, and 3 speed manual trans. Assume it's the SM318 but I don't know how to confirm that. In any case, do you think this would cause a bunch of oil to leak out? Seems like it to me.

[61_FL_Apache]

I had a combo like that on my 65, but dont remember what was covered up or if some of the flywheel was exposed.

[Nanook]

It seems you are missing part of the inspection cover...I can try and get a picture when I am in the shop. Could be a pan gasket or rear engine seal leak.

[Nanook]

Try this....

[Praxiss454]

Thanks Nanook, got a part number by chance? Having trouble finding it for sale anywhere that fits my engine/trans.

[hotrodder]

I don't think the cover is going to cure the leak. Most likley rear main seal, or pan gasket.

[vetnat]

Hi Praxiss. My truck was also missing this piece. 235 and 3 speed manual trans, so the cover looks a bit different on mine. I got the cover from a wrecking yard, but you could try Aspen Auto.

[Captainfab]

You have either a leaking pan gasket or a rear main seal. The missing cover has nothing to do with the leak.

[Praxiss454]

Thanks for confirming, Captainfab, hotrodder. It sounds like in order to change the main seal I'd have to drop the oil pan so I might as well do both at the same time.

[dracko]

Try to get a 1 piece felpro blueline pan gasket. They’re the bees knees compared to the old ones you have to piece together and join with silicone. They also come with little tabs that hold the gasket in place while you install the pan.

[The Rocknrod]

https://www.summitracing.com/parts/FEL-OS34509T/
Best ones I have ever used.

[61_FL_Apache]

I used one on my 61 and loved it!

[geezer#99]

Originally Posted by Praxiss454

Thanks for confirming, Captainfab, hotrodder. It sounds like in order to change the main seal I'd have to drop the oil pan so I might as well do both at the same time.

Whoa! Backup!
Never assume anything!
First order of business is clean up the oil mess. Clean enough to eat off it. Clean enough to see where it’s actually leaking from. Start at the top and work down.
Most of that oil is likely from the valve cover. Somewhere high up and to the front of the motor.
I had a strange leak once on my old 283. Valve cover leaking at the front. Ran down to the pan, along the pan rail and showed up on the tranny shift rods.
So before you put a wrench to it or open your wallet real wide, do yourself a favour and find the source.

[dracko]

Valve covers, timing cover, pan gasket....have some fun and do’em all with good gaskets. You won’t regret it, nice having a 60 year old truck that doesn’t leak.

Of course, it’s a lot more fun if it’s on an engine stand and you don’t have oil dripping in your eye as you put the pan on.

[Praxiss454]

Originally Posted by geezer#99

Whoa! Backup!
Never assume anything!
First order of business is clean up the oil mess. Clean enough to eat off it. Clean enough to see where it’s actually leaking from. Start at the top and work down.
Most of that oil is likely from the valve cover. Somewhere high up and to the front of the motor.
I had a strange leak once on my old 283. Valve cover leaking at the front. Ran down to the pan, along the pan rail and showed up on the tranny shift rods.
So before you put a wrench to it or open your wallet real wide, do yourself a favour and find the source.

Valve cover gasket is new and that area looks clean, but I agree cleaning everything is a good first step. Though I'm not entirely sure how to accomplish that with the engine still in the truck. I've read dollar store oven cleaner is good.

[Captainfab]

To my knowledge, Fel Pro doesn't make the one piece reuseable pan gasket for the 230/250 I6 that the OP has.

Originally Posted by dracko

Try to get a 1 piece felpro blueline pan gasket. They’re the bees knees compared to the old ones you have to piece together and join with silicone. They also come with little tabs that hold the gasket in place while you install the pan.

Originally Posted by The Rocknrod

https://www.summitracing.com/parts/FEL-OS34509T/
Best ones I have ever used.

[Praxiss454]

I didn't see any single piece oil pan gaskets, so I went w/ the multi piece from rockauto. Gonna try to get all that gunk cleaned off this weekend and see what I'm working with before dropping the pan.

[Chevy Fleetside]

Thanks for the thread. Reminds me I have to do my oil pan/rear seal also. woo hoo.

[factorystock]

99% positive the rear main seal is leaking, not the pan gasket, seal probably hard as a rock on an original never rebuilt 50+ year old engine. Very difficult to change out with engine still in truck. There should be a rectangular cover plate in the open area. They are often left off or lost after a clutch job. This is what it looks like and may very well be correct for the 230 250 also https://www.ebay.com/itm/1956-62-CHE...JZGf1X&vxp=mtr

[Railroader]

My 250-6 is leaking also. Replaced once when I did oil pan. Now Pan doesn't leak, seal does.

Any hot tips on replacing seal?

[rvrfoot]

The rear main seal is leaking.

[Praxiss454]

With the help of some kerosene, some degreaser, and a power washer, I cleaned up the engine reasonably well, and then drove it around for a while. Most of the engine looks to be dry/leak free, but it looks like there is some fresh oil by the rear main seal.

I know there are a bunch of threads on this, but I see some conflicting info. On my 65 GMC 1000 w/ the L6 230, do I need to unbolt or loosen the engine, and jack it up in order to get the oil pan off? In my GMC Maintenance Manual, the procedure for changing the rear main seal does not include this step.

I'm not looking forward to dropping the pan. It looks like a PO used gorilla glue or some kind of slight expanding foam to seal the pan. The pan has also been dropped and sprayed blue, but the blue is peeling off and I can see the original red beneath it. So Ideally I'll completely remove the pan, clean it, spray red again, and button it back up.

[Praxiss454]

Originally Posted by Praxiss454

I know there are a bunch of threads on this, but I see some conflicting info. On my 65 GMC 1000 w/ the L6 230, do I need to unbolt or loosen the engine, and jack it up in order to get the oil pan off? In my GMC Maintenance Manual, the procedure for changing the rear main seal does not include this step.

Well, rain in the forecast here for the next week or more, so not sure I'll get a chance to dive into this for a while. One of the drawbacks of not having a garage with enough space to work in.