Crank Seal Repair

neilca · 09-26-2010, 02:28 PM

Has anyone repaired the groove in the crank that wears in with the main seal? I have used repair sleeves on other engines, I was wondering if they make a sleeve for the 2.4/2.7 crank with six bolts.

Eagledriver · 09-26-2010, 03:09 PM

I've not heard of a sleeve for that. Might be a good idea though. Most of us just try to put the new seal in at a different depth.

-Andy

Walt Fricke · 09-26-2010, 08:01 PM

There is such a thing, though it is not specific to a 911. Sealsit or something like that. Website, information, etc. It looks like it is easiest to install it on a crank which is out of the engine, but I can see how it could be put in without disassembling the engine. You'd need to know the exact length you needed to cut it to before installing.

Basically it is a very thin walled steel cylinder, which is a bit narrower than the crank snout. It is wide on one end. You put that end on, then use a cylinder larger than the crank and the seal to pull it over the crank. It is so thin it expands a bit, so it ends up locked in place.

When it is in, with the bell part up against the crank parts, you grab the bell end with something and it tears off. This part looks easier to do with the crank on the workbench.

And you have to know just how long to cut it before you install it, because you can't let it interfere with the flywheel. I did not find that information anywhere. Easy to measure the depth of things, but hard to guess how much the bell part affects this.

I decided this was something to do on a rebuild if I still thought grooving was the cause of leaking.

Do a search of posts - that's how I found out about it. Clever system. They make thousands of different diameters. One of them looked like it was just right for a 911 crank.

Walt

AlfonsoR · 10:22 AM

RolyRolo has a good point. If your engine has excessive blow-by, this might lead to oil leak at the crank seals. However, if you do have a grove, another solution I have seen is a spacer.

Normally, when you install a crank seal, you leave it so that its face is flush with the housing. On an engine with 200,000 miles I had a leaky rear main seal and I wanted to make sure that the new seal was not going to leak, therefore i wanted the lip seal to ride on virgin material on the crank. So the spacer is basically a precision ground washer that was 0.020 thick and a few mils smaller on the OD than the seal.

You install the seal as normal, flush to the housing, then set the spacer on top of the seal and knock it in down further until spacer is flush with the housing. Then just remove the spacer. So now, the seal is effectively 0.020 further in to the housing and should be riding on new cranks material. This is assuming you have sufficient depth in the housing to do this.

If the depth of the seal housing is the same as the width of the seal, you could also put the spacer behind the seal so that it makes the seal stick out by the thickness of the spacer, but you need to make sure there will be no interference to other parts.

Walt Fricke · 09-27-2010, 01:02 PM

If the seal is pushed in too far, its backside will rub on the crank. I think the round thin part which serves as a slinger? Not good, anyway.

If it sticks too far out, the external face of the seal will rub on the lip of the flywheel. Not good either.

I know there is some leeway inward.

Haven't measured what it is on the flywheel side, though that would be a simple calculation.

And might vary with the case, as the horizontal exterior aspect of the case at the seal is not, as I recall, machined. It is nice if both halves are in the same exact plane, as that allows you to be sure you have the seal straight. But not essential.

I hate installing seals. At one time I thought I had it down - put a dab of gasket cement on one part of the seal. Install with fingers, with cemented part in a bit more than rest. Then start pressing/tapping seal in. Cemented part helped keep the deep side from popping out when you pressed opposite it.

But I have lost the touch.

Anyone made up a main seal installer? I have both 6 and 9 bolt cranks, and the factory/aftermarket installers for each are really rather expensive. I think I know how the factory installer works, but don't have a lathe or mill to get things all square.

nreed · nreed's Garage

There are two things you can do to fix this problem.

1. SKF Speedi Sleeve #99353 ( not sure if this one is correct for your model - see catalog below )
2. The place where I suspect my seal was leaking from was between the case and the metal part of the seal that mates with the case. Use a non hardening, high temperature paste like Curil T.

Presto no more leaks for me. I put in the sleeve for insurance but I doubt now that was the problem.

SKF Catalog:http://www.skf.com/files/778249.pdf

Schwarzeritter · 09-27-2010, 07:23 PM

A lot of things are possible to repair, if you plan to be nice and drive nice they can get you by for a limited amount of time. But Crankshaft Seal = Replace, not repair, however I know and understand money and budget and so on are tight for many. It depends on how bad the damage is. How excessive the leaking is. Leak-Down / Compression test will give you a idea of you have excessive losses or are waaay out of spec.

If the leak is small and the compression is healthy well then you can repair it.
If compression is bad and the leaking is excessive or the leak is just excessive you
need to replace it.

Good luck-

Walt Fricke · 09-28-2010, 12:21 AM

I wish I had Norm's good luck with Curil T.

I could see visually that my leak was coming not from the crank side seal (because the rubber covered face of that seal was dry, dusty, etc.). But from under the seal OD (ribbed rubber over a steel shell) at the bottom case parting line or nearby.

It would do this with the engine out and the flywheel off after I had cleaned the area all up, which means oil with no real pressure was able to wick itself out. I think after Curil T it may not be leaking as much. Might be wishful thinking, as I am not sure about the next step. Doesn't look like it is coming from the case parting line due to lack of sealant there.

At least it is at a low rate I can live with.

Walt

neilca · 09-28-2010, 03:07 AM

Thanks guys,

This engine is not built yet so blow by is not the problem nor would i suspect blow by could ever blow a main seal. The engine breather is more than adequate to relieve internal pressures. I inspected the crank and found a groove cut in the crank from a previous life. I have used the Speedi Sleeves in the past with very good results. I will check the catalog nreed provided.

nreed · nreed's Garage

I actually used a slightly stickier product from Mercedes-Benz. Part number A0019892520 (called "Special sealing compound"). Similar to Curil-T but available from my local Benz dealer.

Sorry, I should have said this before.

Walt Fricke · 09-28-2010, 12:25 PM

Neil

Since you have used Speedi Sleeves (what I was thinking of - didn't realize SKF had a similar product), could you post something when you are done? How did you cut to length, for instance. What length (or method of determining it) worked. Could the bell end be removed after installation with the crank in the engine already? Or are the dimensions of the bell such that you can just leave it and not have it interfere with the innermost lip of the seal?

My recollection is that the Speedi Sleeve folks don't have one in the right diameter range which is just the length you would want, so shortening a longer one is in order. Someone told me that for cutting to length you could find a wood dowel of the right size, put it into the sleeve, and cut. That way the cut on such a thin metal tube would have a better edge.

It is always good to hear details from someone who has done it. While relocating the seal a bit in or out (and tightening the garter spring) are the most common suggestions for dealing with seal ID problems, these sleeves sound like they are a better mousetrap for the long run.

Walt

neilca · 09-28-2010, 12:37 PM

Will do Walt,

I was thinking to install the sleeve on the crank then put it in the lathe and cut the excess off. If I knick the crank it will be well outside the seal area. I am also cross drilling the mains and grooving the bearings so I will add those pics too.

SuperOldSchool · SuperOldSchool's Garage

I found an 87 for sale which I am seriously looking to purchase. Owner has all records( sent me pdf's). Has 53k on it. He just had the front crank seal replaced. What causes it to leak? Can it be due to lack of use/driving? Thanks!

HawgRyder · HawgRyder's Garage

Chicago Rawhide make seals that have more than one sealing surface on them.
Since they have more than one, at least one should be in a new position on the crank, avoiding the groove that is there.
This is another possibility for you.
Bob

AlfonsoR · 11-05-2010, 08:48 AM

Quote:

Originally Posted by HawgRyder

Chicago Rawhide make seals that have more than one sealing surface on them.
Since they have more than one, at least one should be in a new position on the crank, avoiding the groove that is there.
This is another possibility for you.
Bob

That's interesting. If a lip seal has more than the usual one lip, then the outer most lip will run hotter. The lip seal does need some oil to lubricate and keep cool, so I guess the outer ones might be sacrificial, being that they may not get sufficient lubrication?