slivel

Situation. Engine out rebuild. Short block disassembled, cleaned and assembled by reputable (I thought) machine shop. New main bearings, rod bearings, rings, balance shaft bearings, all seals. After reinstall in the car the rear main seal leaked immediately.

We worked with the machine shop but got little satisfaction. They said it was the oil pan gasket. We let them have the car for a few days, and all they did was slop some sealant around a few places and of course it did nothing. So my son-in-law and I changed the oil pan gasket and of course it still leaked because as we said all along that it was coming from the rear main seal area.

So next we replaced the rear main seal, it appeared that the original seal was slightly cocked and not installed square so we thought that was the cause. Not so, the new seal leaked almost immediately. We are fed up - what could be causing this?

This was not my first RMS change on a 944T so I'm confident that we did a good install. A fully freshened engine with a good seal shouldn't leak - but this one does.

Thoughts running through my head are:
1. Crank not straight and too much runout causing the seal to leak. Not likely because the engine is smooth running with no vibration at the flywheel clutch area.
2. Area behind the rear main bearing and in front of the rear main seal is a cavity. There must be some way for oil to get back in the pan - a drain hole I'm guessing. If oil can't get back into the pan and builds up in the cavity it would seem that this could be the cause. Plugged drain?

So here is the question for the wise ones here on the board. What is the likely cause of this leak? Solutions?

Please don't suggest going back to the machine shop. Since short block was delivered to them, they can say just bring back to us the short block and we will fix it which is more work than fixing it ourselves - or at least I thought it was until doing both oil pan gasket and RMS ourselves.
Thanks,
Steve

Teddy952

I replaced my RMS while I was doing my clutch. I thoroughly cleaned the area and tapped in my new RMS with a piece of matching diameter PVC pipe. After starting the engine I noticed a small drip running down from the RMS area. I hoped that a couple of heat cycles would of 'seated' it better. It did not and I had to rip it apart again and redo the seal.

I purchased a new seal, different from the new one that leaked, and bought a tube of Curil-T sealant.

http://www.pelicanparts.com/cgi-bin/...be%20%20%20%20

I can't remember what color the RMS is that worked. I believe one was black an the other was a reddish brown. The sealant along with the different RMS did the trick. Maybe another RLister knows what RMS to use. I do remember the RMS that did not leak was a lot tighter fitting. I can't remember which one sorry....

StyleLab

I used the black one with curil-t. I hear the brown one is better but haven't had any trouble using 2 black ones in the past. You need to make sure you don't tap it in too far and that your bore is free of scoring. Ymmv

Nick

Techno Duck

I used the Elring seal which from what I read is the better of the 3 available. Instead of using the manual recommended Curil-T I used Hylomar. I have the RMS press (seal arbor) I can loan you if you want. Makes seal install a snap.

fortysixandtwo

I wonder if they forgot to add case sealer at the right rear of the lower block assembly.

mtnman82

+1 on the Elring being best. In fact, it's the only one I'd use... I wound up with three different types as the first didn't look like it was going to seal at all, even after I pressed it in. The Elring was the clear winner and I didn't want to have to re-do that job.

Bri Bro

The seal needs to be driven all the way into the seat. When it is, it sits a little in from flush, at the edge of the beveled edge. There is a small slot in the seat and if the seal isn't driven all the way in, it leaks. That is a large seal, if it is pushing in without a seal driver, it can deform and leak. If there is any scratches, groves or foreign material on the crank, it will leak.
https://rennlist.com/forums/4389625-post18.html
https://rennlist.com/forums/4387351-post17.html

Some good posts on the subject.

Tom M'Guinn

I tried the tap it in method and it leaked. So I bought the tool and pressed the seal in evenly all the way until it stopped (per the FSM) and it was fine with no leaks. I did use Curil T on the outer surface. Also, take a look at the crank and make sure it is smooth where the seal rides.

slivel

I used the home made PVC seal tool and it worked fine. We drove the seal in until it seated - a couple of mm in from the edge. The weird thing is that on start-up we ran the engine for about 15 minutes and no leaks at all. So it seals dynamically, but when shut off it immediately starts leaking - about 10 drops. It makes a puddle about the size of 50 cent piece.

We used the Victor Reintz seal both times - the orange/brown one. If and when we redo the seal, I won't use that brand.

To avoid a redo right now - we are burned out on this leak, we are going to try and attach a small sheet of aluminum with JB Weld to the back of the pan and direct the drops away from the crossover. I know that is a crummy band-aid fix but I just can't face a redo right now.

Tom M'Guinn

You can probably find some bolts nearby (oil pan bolts?) where you can attach your bandaid, rather than mucking up the motor with JB Weld.... What oil are you using? If synthetic, you might try dino oil, specifically the kind made for old cars.

Chris Prack

Pack the back of the seal with wheel bearing grease prior to installing it. The grease will keep the spring from popping off the lip of the seal while you are knocking it in.

mtnman82

I have the tool. I put the Victor in first, pressed in all the way, and didn't like the way it fit. The thin 'sealing' rings on the outside of the seal - it didn't look like even one was fully seated where the notch is. I ordered a different seal that looked better (forget the brand, still have it) but then saw a pic of the Elring in a thread here on RL and decided that was the one I had to have. Elring + Curil-T + seal press = no leak for me. I did make a tool with PVC, but the press fits perfect. The press does have an issue with one of the draw bolt holes being off slightly - messed up for such an expensive tool - but it is definitely usable.

Techno Duck

Yea if i remember right 2 or the 3 bolt holes work or something like that. Still works fine. And a thanks again to mtnman82 for loaning me the tool when i did my clutch job about 2 years ago, probably saved me from having to do it again.

I ended up buying the arbor that came up for sale a few weeks ago, figure i will never need it again but who knows. Anyone is welcome to borrow it if they want.

Mike Lindsey

Take 10mm of length out of the spring on the RMS.

slivel

Is shortening the spring something you always do, or just with some brands of seal (like Victor Reintz), or only when you have a problematic crankshaft that doesn't want to seal?