rear main seal

[dede911]

Hi,

I have a small grove in the cranckshaft surface where the seal lip runs.

Should I install the seal a little bit deeper?

What is a little bit?

The previous seal was flush with the case

Tx,

dede

[Superman]

I've heard there are oil ports behind that seal that can be plugged by a seal that is installed too deep.

[dede911]

I could also install it 2 mm out of the case...

[Superman]

Keep asking. Someone here should know. I frequently place seals into locations where they will not run on the old, tired shaft locations. So, it's a good idea. Someone will know whether this can be done safely on the 911 rear main seal.

Sometimes, seals are made which have the lip in a different location from stock, so that the lip is in a new spot while the body of the seal is in the same spot. But I don't know if this seal is available in that configuration.

[KTL]

Yes. You can install it deeper but you do not want to "bottom it out" otherwise it will pop out like Super said due to the drainback holes being clogged- a buildup of oil pressure will push it out.

I have the RMS installed a smidge deeper than flush-with-the-case on my 3.2 engine and it works fine. In your situation, if you don't have the factory seal installer/press tool, I would do what you suggested and install it protruding a bit from the case. It's easier to leave it sticking out a bit than to decide how far is too far when driving it past the case surface.

As long as you've got good engagement of the seal OD, you should be fine. I'd leave it sticking out as little as possible to still keep the sealing lip on the crank in a fresh location.

[88911coupe]

What keeps the seal in place after installation? It seems like it could meander in and out a little at the crank turns or am I missing something...

[KTL]

The press fit of the OD of the seal keeps it in place. A smear of oil around the inner lip and OD are good to help the seal slide in without tearing the rubber covering.

Wayne's book recommends Curil T around the OD of the seal, but I just can't buy into that. Curil T is a non-hardening sealant, sure, but there's no need to seal the OD of the seal- that's what the rubber does! Plus there's been instances of peoples seals coming out when using the Curil T. I say install with nothing more than a light swipe of oil and you're gold.

[dede911]

In the past I have been building a few (non P) competition engines, and always managed to get them oil tight. If I had any doubt about the crank surface, I installed a speedi sleeve...

This is the first time I work on my P engine and read a lot of horror storys about the RMS...this in combination with the grove I found, makes me nervous...

At this moment the seal is 2mm out of the casing. Before installation I lightly coated OD and ID with some grease so that like KTL mentioned it easily slides in.

I ordered a spare seal (will get it tomorrow) in case...

Should I leave it as it is, or removing the seal again and measuring everything out to try to install it deeper?

I'm sure that there is a lot of experience on this forum

Please help me to do it first time right

Tx,

dede

[Jim Sims]

Ted Robinson used one of these sleeves to restore a grooved RMS land on '73 911 crankshaft I sent him for inspection and polishing:

http://www.chicago-rawhide.com.au/Products/speedisleeve.htm

[dede911]

OK

What have I decided ?

This morning I spoke with an official P mechanic about this prob. He was not happy to leave the seal 2 mm out of the casing. It is true that the engagement is the casing is not 100% because the max stress in the metal carrier is only reached after being completely in the housing.

I cut a piece from 1" from the old seal and test fitted it to check the exact position regarding the grove and the oil hole in the casing.

Based on this measurement, I decided to install the seal 2 mm deeper than flush.

Thanks for your support

dede

[MBEngineering]

HI dede911
Just be careful when you put the seal is and NOT like the one below, as you can see the seal is fully in and blocking all the oil return holes for the rear main, and is touching the flange on the rear of the crank, this seal is in approx 4-5 mm to far. If the lip on the crank is bad then get it polished out, if not then I would remove the seal spring and remove approx 1mm from the end of the spring and then fit the oil seal in the correct poss' flush with the case.







regards mike

[goldsc78258]

I went thru the same ordeal, I installed the seal too deep and it was leaking oil like crazy.

Did some reading on several posts here and reinstalled it flush with the case and there is no more oil leaks.

I didn't shorten the spring but that sounds like a good idea

[dede911]

Mike,

Tx for your reply

I put it in exactly 2mm

Do you think this is OK?

Tx

dede

[goldsc78258]

I went thru the same ordeal, I installed the seal too deep and it was leaking oil like crazy.

Did some reading on several posts here and reinstalled it flush with the case and there is no more oil leaks.

I didn't shorten the spring but that sounds like a good idea

[dede911]

Goldsc,

did you installed it also 2 mm deeper than flush, or botommed it out?

dede

[MBEngineering]

HI dede
should be OK , as long as it is square to the case, as I posted the seal was fitted in the photo way to far in at a prox 4-5 mm.

regards mike

[dede911]

Mike,

the seal is absolutely square to the case.

I made a gauge to check the distance seal-case: it is exactly 2mm checked around the seal.

Regards,

dede

[goldsc78258]

I installed it completely flush and it worked perfect

[dede911]

Job done...


droped engine , replaced clutch, replaced seals gearbox and engine, major service on engine, shroud powder coated., valve covers glass blasted..

gearbox shifts very smooth...completly different than, before...also 915 boxes can be smooth...

Thanks to every on the forum

Regards,

dede