Who has done this without pulling the engine and how successful were the results? (1980). What seal is recommended, what oil pan gaskets are best to use? Thanks in advance.

 

This is pretty good - Hope this helps

........................................ .............................. tom

You Tube

 

I did it a couple years back. It was fine other than taking 3 times as long as I had planned. Felpro 2912 is the one to get.

 

In the video, the mechanic left one end of the seal extended out of the bearing cap. Looks like a good idea, but the nanual shows the seal flush with the bearing cap. Any thoughts on this?

 

It was at the end of video - think he needed both hands

But Yes, both ends of the seal need to be flush with cap and block

........................................ . tom

 

That was a method that was done a number of years back that the theory was that, that gap in the seal and the gap in the cap to block did not coincide.

 

I offset them. No leaks

 

Yes i read about Seals
letting the ends protrude
trim ends flush
add dab silicon to ends of flush seals
above plus on machined surface of main cap

........................................ ....................... tom

 

I did mine last week and have done a couple more in the past. It only takes a couple hours to do. I've always offset the seal and have had no problems. Don't cheap out and buy a good seal.

 

I like the idea of an offset seal. Any difficulties getting the seal offset inserted properly without damaging it?

 

The seals come with a little shoe horn type tool to help slide it in.

 

Not if you're careful.

I've done a couple of rear main seals on C-3s, over the years, and I've always offset them about 1/8'-3/16". I also dab a little RTV on the main cap, as shown in the picture in a previous post.

The trick, when offsetting the seal, is when you ease the main cap in place, have the bolts CLOSE BY, so after guiding the ends of the seals in place, you hold the main cap snugly in place with one hand, and install at least one of the bolts, with the other hand, so the cap doesn't drop out of place.

The easy part, with a C-3, is that the engine sits far back enough in the chassis, so the oil pan can be dropped without having to raise the engine from the engine mounts. With respect to pan gaskets, I don't know the part number off hand, but go with the Fel-Pro 1 piece gasket, with the steel inserts.

Also, while you're in there, (famous phrase!!) I'd recommend installing a Melling or Moroso oil pump driveshaft, the one with the steel retaining collar.

 

Hey Z06

Take a moment and explain each photo. Not sure what the second shows...pointer at the main cap

 

How do you tell the difference between a rear main cap seal leak or a rear oil pan gasket? I replaced all the oil pan gaskets couple of years ago and see I'm still seeing a leak...thinking its the rear main seal.

 

Unfortunately, it's very difficult to differentiate between the two, other than to say that if the oil you see is on the rear of the pan, it's likely the pan gasket. If the oil is migrating into the bell housing, it's most likely the rear main seal. Probably a good rule of thumb, is if you suspect it's the pan gasket, and plan to replace it, replace the main seal too, since you're already over half way there....

That might not be the best advice, but I'm not sure what else to say.

 

Photo #1 - shows where you would put silicone on the rear main cap machined surface - to insure no leaks

Photo #2 - the pointer is just pointing to the rear main cap installed and the grove where the rear oil pan gasket goes

Photo #3 - shows a removed rear main cap with a worn/bad rear main bearing - meaning you had better give a look at the crank for wear/groves

................................. tom

 

If you offset the seal, the joints created are NOT on the same splitline as the bearing block. It helps to 'heal' the joints in the seal with the added support without that splitline.

Clean the ends of the seal halves with a good solvent to eliminate all oils/greases before dabbing on the sealant. Also, put very little sealant on the seal ends; you don't want it to squish out onto the working area of the seal.

 

With the weather cooling here, I thought I would go ahead, change oil and determine where the leak was coming from. It was red and seeing no wet on the oil pan, concluded its coming from the transmission. The flywheel cover had a drop hanging from it while the tranny pan was wet. Oil pan...dry!

But, no main seal leak. I did go ahead and order that one-piece oil pan gasket...that sucker is thick. It came with the bolt kit including the four longer bolts. But my cork gasket is holding up nicely.

So what am I looking at in terms of getting at the tranny leak. I'm assuming its where the shaft enters the engine/flywheel.

 

Transmission oil may be leaking from the front seal on the transmission (charging pump seal) into the inspection cover area; or it could be leaking from some external area and running down the outside of the inspection cover. You must thoroughly clean the outside of the inspection cover and then run your test again to know which scenario you really have.

If the leak is emanating from INSIDE the inspection cover, there is really nothing you can do for it short of a rebuild of the transmission. Can you replace JUST the input seal[s]? Yes. But, the seal in not the problem. The CAUSE of such a leak is the wearing out of the input bushing which allows too much side motion of the shaft...and THAT causes the seal to wear out. Change just the seal and 6 months later (or less) you end up with the same problem. PLUS, the internal seals and friction plates are probably getting well worn anyway, so you might as well just get it rebuilt and be done with it. (Or take that opportunity and swap it out for a rebuilt overdrive auto tranny! )

If the leak is running down the OUTSIDE of the inspection cover, it is likely coming from the trans pan gasket or some external seal in that area. Again, clean the area of ALL oil, drive the car some more, and find the REAL source of the leakage. Then you'll know what to fix.

 

Got it! Watched a Youtube video with a guy removing the pump from a THM 350 with what looked like a flywheel puller but adapted to that tranny pump. So I've got the visual. I may also have a shifter shaft seal leak but I'm sure the fluid would not migrant upward to the flywheel cover. Looks like something much more manageable.