Flywheel Seal-Did I do something bad?
 

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

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.

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.

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

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.

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.

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

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

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

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.

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

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.

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.

http://forums.pelicanparts.com/showthread.php?s=&threadid=167287&highlight=cranks haft+seal

http://forums.pelicanparts.com/showthread.php?s=&threadid=268387&highlight=flywhe el+seal

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?

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

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? :confused:

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.

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

from

http://forums.pelicanparts.com/showthread.php?s=&threadid=161348&highlight=flywhe el+seal


Again Wayne quote:

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

from

http://forums.pelicanparts.com/showthread.php?s=&threadid=93923&highlight=flywhee l+seal

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:

http://forums.pelicanparts.com/uploa...1142784291.jpg

http://forums.pelicanparts.com/uploa...1142804618.jpg

http://forums.pelicanparts.com/uploa...1142804642.jpg

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

http://forums.pelicanparts.com/uploa...1149365647.jpg

http://forums.pelicanparts.com/uploa...1149365667.jpg

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.

Chris:
Thanks for the pictures and the threads.

http://forums.pelicanparts.com/showthread.php?s=&threadid=93923&highlight=flywhee l+seal

From what I have seen on this, and other threads, half the people say it doesn't matter, and the other half says: flush (Or a little past flush)
The one reply with picture showing the seal all the way into the recess states that the engine run dry.

When a seal leaks, there could be many different reasons.
Seal not installed square to the crank,
Insufficiant contact of the lip due to rough surface, or worn area on the crank-shoulder, or differences in diameter.
Bore out of round.
Crank not centered in bore.
Seal installed without sealant on the O.D.
Damaged lip during install.

Unless I am missing some unknown factor, if everything is optimal, it should not matter if the seal sits deeper.
And why did Porsche engineer a deeper recess for the main seal but not for the seal in the #8 nose-bearing?
What actual pressure inside the case is applied to the main seal?
Certainly not the high pressure from the pump.

I guess I am looking for someone who installed the seal (With everything optimal) deep into the recess and either had no leak, or can give us actual reasons why this caused problems.

I just replaced my rear main seal in addition to my clutch.

Attached are pictures of the old seal prior to removal. If you examine the pics closely you will see it sits even with the case. I purposely tooks these pics for reference for anyone replacing the seals as this question comes up often. I hope this helps.

I installed my new one flush with the case.

http://forums.pelicanparts.com/uploa...1149436967.jpg http://forums.pelicanparts.com/uploa...1149436986.jpg http://forums.pelicanparts.com/uploa...1149437002.jpg http://forums.pelicanparts.com/uploa...1149437019.jpg

I put it on while I was putting the case halves together. My concern is that it was too far into the case and the squeeze out from the sealant caused the leak. If I did it again I would put the seal in after mating the case. Will take pictures and let you know what happened. Will be working on it tonight.

Howard:
Thanks for the pix; That's what I call a leak!
Looks like it is coming from the lip. I take it that the damage on the seal is from a screwdriver prying it out?
The notch shown on top is meant for "hooking" into the old seal for removal.
What is that red stuff towards the pilot bearing O.D.?
Did you install the new seal dry?

Michael:
Much appreciated. Must have been a lot of "squeeze-out".
Will you install the new seal without any sealant on the O.D.?
My feeling is that a VERY THIN layer of Curil-T will act as a lubricant to ease the new seal in and act as a sealant on the O.D. after.
After more research: It seems that most people install it flush although there are some who went a little deeper. The Porsche installation tool insures that it sits square but will allow to go past the case-edge.
To my mind, the most important issue is to insure that the seal sits square. If it is installed without the tool, the edge serves as a reference point to stay square.
The bore has to be true, the surface on the crank has to be smooth/polished for the lip to ride on.
There is a small hole in front of the seal (Under the #1 bearing) to allow the oil to circulate but, the hole is not on the bottom, it's more to the side.
Some other engines, like my Volvo, have a groove machined all around in the case so that any oil from a leaking main seal is caught and drained out without any harm.
Hope that the second install will work out and any pix are much appreciated.

Now I know why you cannot push all the way into the case
 

I got my 964 case back from the machine shop today. Take a look at these pics, there are two drain holes behind the seal, and if you push the seal all the way into the case you will absolutely block them. Then where will the oil go?

Yeah, exactly :)

http://forums.pelicanparts.com/uploa...1149739103.jpg

http://forums.pelicanparts.com/uploa...1149739127.jpg

HI maybe you can see now why you do NOT put the seal all the way in, not only the hole blocked off, the inside of the lip on the seal is up against the case as well (have just pulld a 3.6 in bits and checked), so very little or no oil return, oil presure from the rear main will build up and you have a leak!!!.
did your mum not tell you to put things back where got it from?? IE; put the seal back as you found it, flush with the case, P9126 fits the seal just in from the edge of the case.

regards mike

Thanks Chris:
The question was about going a little past flush, not to push the seal all the way in.
Your pictures doesn't show the bearing.
The #1 bearing is different from all the others and has a shoulder on each side making it impossible for the seal to block the holes even if the seal is all the way in.
I am not promoting to install the seal against the #1 bearing; I am saying that I cannot see a problem with going a little past flush.
After looking at different posts, some people have gone a little deeper without problems.
There can be a variety of reasons for a leaking main seal other than position. Most seals are installed flush and still leak because of other factors.
Please, install the #1 bearing halve and measure the distance from the case edge to the bearing shoulder; then measure the thickness of the seal and give us the numbers.

Damage is from screwdriver. I have no idea what was that red stuff. I lightly coated the inner portion of the seal with fresh oil then tapped it into place with a block of wood.

These are the pictures after removing the leaking seal. I used yamabond 4/Threebond 1104 to seal the outer perimeter of the new seal. Was so impressed to see how it sealed the cam towers to the heads. Had to remove somehing to fix it and the sealant sread was perfect The first picture of how it looked after being installed the first time. The first time I used yamabond 5 to seal it.


http://forums.pelicanparts.com/uploa...1149826236.jpg

After removing the leaking seal
http://forums.pelicanparts.com/uploa...1149825455.jpg

New one installed and did not leak after a 25 mile run to start the breakin. :D
http://forums.pelicanparts.com/uploa...1149826433.jpg

Howard: Just oil on the lip but no sealant on the O.D.?
Thanks Michael: Good news: No leak. Great pictures, ignore my PM.
I wonder if the 3.2 case is different from the 3.0 because I don't see the overhanging shoulder from the #1 bearing in your second picture.
In Wayne's book, page 130/131, the end of the crank-area shows different: The side of the #1 bearing creates a groove/channel for the 2 oil holes, the crank has a portion on it to be in front of the #1 bearing when installed.
Is the 3.2 case different from the 3.0???

The #1 bearing has thrust-flanges to control axial play of the crank.
The crank has flanges to fit precisely into the #1 bearing leaving a groove/channel for the 2 oil holes in the case.
When removing the main seal, the outer thrust-flange of the crank should be visible.
When removing the old seal, how deep is the recess in the case? xx mm?
How thick is the main seal? xx mm?
Is the case from a 3.0 different from a 3.2 in the main seal area?

Expert comments, and measurements, much appreciated.

Why is the thrust-flange from the crank not visible in this picture?

http://forums.pelicanparts.com/uploa...1149953480.jpg

That's an optical illusion from that photo and the lighting - it's basically flush with the case - I use the end of a tool to tap it in, using the case as a stop-point. I'm not sure why that photo looks like it's not flush, but at that point, it is, or at most, it's about a 1/16th of an inch into the case.

-Wayne

Here's a better photo:

http://www.pelicanparts.com/techarticles/911_clutch_replace/pic15.JPG

-Wayne

Great shot of an old, leaking main seal.

Wayne: My question still is:

On the engine you rebuild for the book: Was there any leak from the seal shown about 1/16" past flush on page 135?

Much appreciated :)