failed main oil seal

356 Porsche-related discussions and questions.
Message
Author
User avatar
Jim Clement
356 Fan
Posts: 1461
Joined: Tue Oct 26, 2010 10:46 am
Tag: 1957 356 A Coupe
Location: Calgary Alberta

failed main oil seal

#1 Post by Jim Clement »

I recently had my engine rebuilt, and it was tested on the test stand for about 5 hours.
so, was safe to put in the car.. but soon there after noticed a oil leak from the front center of the engine... nice clean oil..

so
pulled the engine and had the fellows find the leak.. it was the oil seal.. picture is attached.
I was wondering if anyone has an idea why it would fail like this. it almost looks like it was burnt..
it has the numbers 60 80 10 then NBR

Any ideas
Attachments
P6290260.JPG
 

User avatar
Vic Skirmants
Registry Hall of Fame
Posts: 9279
Joined: Tue Oct 27, 2009 5:02 pm
Location: SE Michigan
Contact:

Re: failed main oil seal

#2 Post by Vic Skirmants »

Hard to tell from the photo, but is that the standard double-lip seal? With the outer lip un-trimmed? That will rub on the flywheel radius and get burnt, thereby causing seal failure. This has been discussed many times.

User avatar
Jim Clement
356 Fan
Posts: 1461
Joined: Tue Oct 26, 2010 10:46 am
Tag: 1957 356 A Coupe
Location: Calgary Alberta

Re: failed main oil seal

#3 Post by Jim Clement »

Vic,
I think it is a standard oil seal ? a better pic is attached.
what should have been done to it prior to installation ?
Attachments
P6300271.JPG
P6300266.JPG
 

User avatar
Vic Skirmants
Registry Hall of Fame
Posts: 9279
Joined: Tue Oct 27, 2009 5:02 pm
Location: SE Michigan
Contact:

Re: failed main oil seal

#4 Post by Vic Skirmants »

That outer lip should be cut off with a sharp razor blade. I also trim the inside of the outer part. There is a metal part under the rubber, so it's easy to tell how far to cut. This puts it further into the case. Practice on the failed one.

User avatar
Jim Clement
356 Fan
Posts: 1461
Joined: Tue Oct 26, 2010 10:46 am
Tag: 1957 356 A Coupe
Location: Calgary Alberta

Re: failed main oil seal

#5 Post by Jim Clement »

is it the outer lip that should be cut off.. as per arrow ?
sorry for the very poor writing skills on the picture..
Attachments
oil bearing.PNG
 

User avatar
Vic Skirmants
Registry Hall of Fame
Posts: 9279
Joined: Tue Oct 27, 2009 5:02 pm
Location: SE Michigan
Contact:

Re: failed main oil seal

#6 Post by Vic Skirmants »

There are two "sealing lips". Cut off the outer one to avoid cooking it from contact with the flywheel radius.
And yes; also cut off the "lip" you show in the photo.

User avatar
DonCichocki
356 Fan
Posts: 521
Joined: Thu Aug 22, 2013 4:29 pm
Location: Lafayette, NJ

Re: failed main oil seal

#7 Post by DonCichocki »

Jim,
I made a fixture for my lathe so I could grind down the width of the seal to fit flush in the crankcase without altering the sealing lips. You need to get the width of the seal down to .312" (5/15"). This seal was in my engine over 24,000 miles and didn't leak. I changed it out of precaution while doing a cam swap.
Attachments
DSCF0360.JPG
DSCF0363.JPG

User avatar
Dave Wildrick
356 Fan
Posts: 1953
Joined: Wed Mar 26, 2008 2:10 pm
Location: Houston, TX

Re: failed main oil seal

#8 Post by Dave Wildrick »

Jim Clement wrote:is it the outer lip that should be cut off.. as per arrow ?
sorry for the very poor writing skills on the picture..
Here's the outer lip that will burn if not cut off:
FlywhlSealTrim.jpg
Dave Wildrick
Houston, TX
#10230
64C coupe
65C coupe

User avatar
Ron LaDow
356 Fan
Posts: 8092
Joined: Wed Mar 26, 2008 11:45 am
Location: San Francisco

Re: failed main oil seal

#9 Post by Ron LaDow »

Credit where due: Tim Berardelli advises that Wolfsburg West offers 36HP VS Viton seals, without the extra lip at $6.00, retail.
He says, and I believe him, that they are dimensionally interchangeable.
Ron LaDow
www.precisionmatters.biz

E Rutherford
356 Fan
Posts: 348
Joined: Tue Oct 26, 2010 2:21 pm

Re: failed main oil seal

#10 Post by E Rutherford »

We sell the viton rear main seal without the lip seal. Its not $6!
Just checked Wolfberg and they say its a viton seal for $6. Good thing I didn't bet the house!
ed
klasse356

User avatar
Greg Bryan
356 Fan
Posts: 3692
Joined: Sat Oct 04, 2008 1:05 pm
Location: San Pedro, CA 90732; Fallen Leaf, CA 96150
Contact:

Re: failed main oil seal

#11 Post by Greg Bryan »

Don - thanks for posting your findings on "thinning" the seal. I've noticed that the current seals seem to be over-flush to the case.
The two lips are a modern advance over the single lip. The area between the two lips should be filled with grease. I will try your .312 dimension next time I need to modify a seal.
Greg Bryan

User avatar
Albert Tiedemann
356 Fan
Posts: 1229
Joined: Thu Apr 03, 2008 2:46 pm

Re: failed main oil seal

#12 Post by Albert Tiedemann »

DonCichocki wrote:Jim,
I made a fixture for my lathe so I could grind down the width of the seal to fit flush in the crankcase without altering the sealing lips. You need to get the width of the seal down to .312" (5/15"). This seal was in my engine over 24,000 miles and didn't leak. I changed it out of precaution while doing a cam swap.

Sometime back a poster remarked that he had found a source for an 8 mm wide seal with the other original dimensions. I am not sure if the material compositions were stated. However, a seal of this width can be installed flush to[as mentioned in the quote] or deeper into the crankcase receiving bore. In either case, and particularly the latter, the sealing lip is likely to avoid the groove, if present, worn in the flywheel hub. Other causes that promote seal failure are many and aside with non compliant seal geometry include installation skewness, sealing surface diameter and roughness and eccentricity, seal surface grooving [deeper than surface roughness], initial dryness of interface and the list is likely much longer. $6 for a single lip Viton seal is a real bargain, but I doubt that you need this newer material.

If you are tapping the seal in with an appliance or using same in support of the Factory recommended tool, Matra 204 or Zelenda US 204, take a look in the classifieds at my offering, aft-P73b to alleviate all pitfalls of the inexperienced installer. First time users get it right the first time. Square to the bore and to the right depth. With a small modification,[similar to that on the driving surface of P73] the tool will finish the seal to any depth greater above the bottom of the crankcase bore on the interval 8 < d < 10 [mm, of course]
Last edited by Albert Tiedemann on Sat Jul 01, 2017 9:34 pm, edited 1 time in total.
Albert Tiedemann, C356C
"The Hermit"

User avatar
Herlin E. Woolery
356 Fan
Posts: 167
Joined: Thu Mar 27, 2008 8:45 pm
Location: Ontario, Calif.

Re: failed main oil seal

#13 Post by Herlin E. Woolery »

In trimming the main oil seal would that be for the T2 engine and later year engine's , thinking when i replace my flywheel , main oil seal I don't remember trimming the main oil seal in my T 1 engine and so far no oil leaks.
Albert buy having the right tool then there is no need to trim the main oil seal?

Herlin

User avatar
Albert Tiedemann
356 Fan
Posts: 1229
Joined: Thu Apr 03, 2008 2:46 pm

Re: failed main oil seal

#14 Post by Albert Tiedemann »

Herlin E. Woolery wrote:In trimming the main oil seal would that be for the T2 engine and later year engine's , thinking when i replace my flywheel , main oil seal I don't remember trimming the main oil seal in my T 1 engine and so far no oil leaks.
Albert buy having the right tool then there is no need to trim the main oil seal?

Herlin
Use of aft-P73b does not alleviate unwanted scenarios associated with untrimmed seals. I have used only single lip seals in the engines that I have rebuilt.
Albert Tiedemann, C356C
"The Hermit"

User avatar
GregVandenbussche
356 Fan
Posts: 339
Joined: Wed May 29, 2013 5:36 pm
Location: San Francisco

Re: failed main oil seal

#15 Post by GregVandenbussche »

you can also have your flywheel machined to get the proper surface for second lip
Bt5 Super - used to be fjord green, was painted brass, then brown... sadness

Post Reply