Flywheel Seal-Did I do something bad?

73TCoupe · 05-31-2006, 06:19 AM

In replacing all of the seals and clutch on my engine I got to the point of putting my flywheel seal in yesterday. I actually used a plastic cup that matched the diameter of the seal exactly to tap it into place. (I cleaned it and snuck it back into the cupboard before the wife got home.) I went easy with it but it seemed to go too far into the case. It is much further in than the one I took out.
Is it supposed to be all the way in or even with the surrounding engine case surface? Will it seal correctly? Is this a problem?
I didn't think much about it and put the flywheel and clutch on. I got to thinking about it once it was in. Hopefully I didn't crush it or damage it.

Thanks,

Steve

Superman · 05-31-2006, 06:29 AM

I'm no expert on the exact geometry of that mating surface, but I have a strong guess that there is nothing whatsoever wrong with your installation method.

Gunter · Gunter's Garage

Steve:
I am working on an engine and noticed that there is enough space in the recess to have the seal sit deeper. I cannot see a problem because the crankshaft has a large enough seal-area.
In Wayne's books, he doesn't refer to this issue.
It is possible that the seal will be pushed back against the flywheel by oil pressure when running.

73TCoupe · 05-31-2006, 07:43 AM

Thanks guys. I saw that the recess is pretty deep. I wasn't sure how far to press the seal into it. I was worried that I may have damaged the seal by running it into the rear of the recess but don't think that is likely. It would probably take a lot of force.

-Steve

Superman · 05-31-2006, 09:09 AM

Running the seal to the back of the recess is not the problem. The potential problem is if the business surface (the interior lip that rides against the crankshaft) is not engaging a flat, smooth surface. It sounds like it is still engaging a flat, smooth surface, so there is no problem. Frankly, automobile crankshafts can get worn under that seal. Imagine that, rubber wearing steel away. Yup. And then, the trick is to install a seal in such a way that the lip is not engaging the crankshaft against that same worn surface.

73TCoupe · 05-31-2006, 09:18 AM

The crank was in good shape all the way in to the case so I don't think that will be a problem. I am probably over-analyzing the situation.

MBEngineering · 05-31-2006, 11:51 AM

HI IT IS IN TO FAR and will have to come out, as you have the seal in to far it now has partly blocked off the oil return holes for the oil to return in to the crankcase, expect a oil leak when the oil pressure is up high!!!

regards mike

CBRacerX · CBRacerX's Garage

See engine rebuilding forum for lots of details on this very concern.

Remove and install flush with case or just a bit indented.

Gunter · Gunter's Garage

I didn't see any documented proof that the position of the main seal in the case is the cause for leaks. Please, show me what I am missing.
On page 135 of Wayne's book, the main seal is clearly past being flush with the case. So, how far is too far?
Some posts refer the the seal wearing a tiny groove into the shoulder on the crankshaft and recommending a slightly different position so the lip of the seal rides on a new surface.
Is there someone who can state with certainty what problems occur when the seal sits deeper in the case?
I would love to hear from someone who has installed the seal past flush into the case and experienced no problems.
So far, just looking at the issue: As long as the seal is not damaged, sits square in the bore, has a clean surface to run on, why should the position be a problem?
None of the books by Bruce Anderson, Wayne Dempsay, or the Bentley Manual warns against seating the seal too deep.
Anyone?

73Tcoupe: Let us know if you have a leak from the seal, please.

MBEngineering · 06-02-2006, 01:50 AM

HI the info you require is 2POSTS up or as it not come up on your screen, at 2100 post i would have thought you would have got the hang of this posting and reading system???????

regards mike

Gunter · Gunter's Garage

I asked JW about this and he is not too concerned.
With the seal deeper in, the lip will ride on a new surface on the crank.
Using Curil-T on the O.D. will help to prevent a leak from that area.

Superman · 06-03-2006, 07:21 AM

The assertion that this will block an oil passage needs to be checked out. I am skeptical, but would almost insist on seeing a seal seating surface myself before deciding whether to tear things down again. I suspect there is no oil passage there to block, but JW would know, and a peek at any two matching naked case halves would solve the riddle.

CBRacerX · CBRacerX's Garage

Rear Main Seal Hell

Crankshaft Flywheel seal

Gunter · Gunter's Garage

To my thinking, oil pressure from the pump is applied to main bearings, crank bearings, cam bearings, pressure-fed tensioners, etc.
Inside the case, there shouldn't be very high pressure against the seals; only slight differences in pressure from the twirling crank/rods/pistons.
None of the books/manuals warn against installing the main seal too deep. If this was an issue, there would be some reference to this.
Anyone?

CBRacerX · CBRacerX's Garage

You seem determined to ignore common experience with this issue. Best of luck with the rebuild!

Gunter · Gunter's Garage

Blah, blah, blah.
Where is the documented proof that this is a problem?
I would love to see some facts, not just conjecture.
The examples cited had nothing to do with position, they had problems with out-of-round in the case-bore and other issues.
So far, I have just seen wild suppositions about installing too deep.
If someone like JW doesn't have concerns, who are we mortals to doubt?

88-diamondblue · 06-03-2006, 08:39 AM

Just put my engine back together. Fired it up Wednesday night. Engine runs great but the flywheel seal leaks. It is pushed all the way back into the recess. Just like the picture in the rebuild book. In searching on this even Wayne recommends it just to be below the edge of the case. The engine is already out and the trans, clutch and flywheel are off. It is the seal that was leaking. New one goes in Sunday night.

CBRacerX · CBRacerX's Garage

Wayne quote "I don't think it matters, but just for reference, I make them mate flush with the surface..."

from

Fly Wheel Seal

Again Wayne quote:

"It should be flush or a little below the surface of the case."

from

How far does flywheel seal protrude?

There is a good picture in the first thread of the area behind the seal, but we really need to see a picture of the area without the seal and crankshaft to get the details clear. These pics from my current rebuild is not quite what we need, but you can see that the bearing oil feed must produce oil flow on both sides of the bearing, and there is nothing but the flywheel seal to keep it from leaking:

CBRacerX · CBRacerX's Garage

Note this is a 964 case, I will have it back in house later next week. This is the closest to what we need to see, but is not quite the full picture

Gunter · Gunter's Garage

Quote:

Originally posted by 88-diamondblue
Just put my engine back together. Fired it up Wednesday night. Engine runs great but the flywheel seal leaks. It is pushed all the way back into the recess. Just like the picture in the rebuild book. In searching on this even Wayne recommends it just to be below the edge of the case. The engine is already out and the trans, clutch and flywheel are off. It is the seal that was leaking. New one goes in Sunday night.

Michael:
Thanks for the update; Please, tell us more.
Did you install the seal with the case-halves together?
Or did you slip it on the crank, like in Wayne's book, and then put the case together?
Did you use Curil-T on the O.D. of the seal before installing?
Is the leak coming from the lip riding on the crank?
Or from the O.D.?
Can you determine why/where the new seal leaked?
The picture in Wayne's book clearly shows the seal somewhat recessed (1/8") but not all the way in.
The bore in the case is the same diameter all the way; the shoulder on the crank is wide enough to allow the inner lip to run on it even if the seal is a little deeper than flush.
To my thinking, if the seal sits square to the crank, the bore in the case is true, Curil-T is used on the O.D., the lip is not damaged and has good contact, what would cause a leak?

And, why would Porsche leave that much room in the case/bore for the main seal to sit and the other seal on the #8 bearing is installed all the way into the recess?

Michael: please, let us know how the new seal works and what you did different this time to install.
Many thanks.