Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 Engine Rebuilding Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Slumlord
 
Porsche_monkey's Avatar
 
Join Date: May 2001
Location: Canada
Posts: 4,985
Rear Main Seal Hell

Just rebuilt 2.7, did everything (except case machining). Runs great, had a few small oil leaks I couldn't live with, (valve covers and intermediate plate on front), which I fixed easily when I pulled the engine.

I also had oil leaking out my main rear seal. (Yes I used Curil-T). I replaced the seal, re-installed the engine and it still leaks! ( It drips after one to two minutes of running).

I just pulled the engine (I'm getting quick at this). It is not a case leak, it is leaking around the shaft seal.

On inspection the seal does not appear to be snug enough on the shaft. I could push a thin strip of paper easily between the seal and the shaft.

What could cause this? On inspecting the case the crank is central but the OD of the case is oval by .004". I do not think that is too much for the seal. I don't think the crank is undersized, but I won't be able to mic it until Monday AM. Is there anything that I could have done wrong on assembly to cause oil pressure behind this seal?

It also appears that if the seal is pushed too far it can push the shaft seal against crank shoulder, this would definately cause or at least encourage a leak. I may have pushed it in too far. (twice?)

I was thinking of slightly shortening the spring in the next seal and aligning the bevel of the seal with the bevel on the case when I push it in. I also plan to fill the engine with oil and tilt it at 45 deg before re-installing as a seal check. (I am afraid I'm wearing out the body mount threads with all the removal and reinstallation )

Are there any shaft kits/sleeves (a la N.A. cars) for worn shafts?

Wayne, John Walker, anybody
Old 06-11-2004, 02:06 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Author of "101 Projects"
 
Wayne 962's Avatar
Hmm, this is an interesting question. You've replaced the seal twice now, and still have a problem. Did you get the seal from us, or did it come from another source (could be cheapo seal?). How's the surface end of the crank there - any scratches?

You know, I've read this four times, and I can't figure out which seal you're referring to? The pulley seal or the flywheel seal? "main rear seal" means pulley seal (rear of the car). Yet, you mention the crank shoulder, which sounds like the flywheel seal.

Please clarify.

-Wayne
__________________
Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of:
101 Projects for Your BMW 3-Series • 101 Projects for Your Porsche 911 • How to Rebuild & Modify Porsche 911 Engines • 101 Projects for Your Porsche Boxster & Cayman • 101 Projects for Your Porsche 996 / 997 • SPEED READ: Porsche 911 (October 2018)

Check out our new site: Dempsey Motorsports
Old 06-11-2004, 03:38 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Slumlord
 
Porsche_monkey's Avatar
 
Join Date: May 2001
Location: Canada
Posts: 4,985
Yes, I think I have the proper seal. I bought a bunch of stuff from you Wayne, but not this seal. It is a silicone 65x85x10 orange-ish, it looks just like the one in your book, and the one in your web-site. I can't remember the manufacturers name, but I will get it for you. Original came with my seal kit, second one (same brand) from a reputable P-car parts shop.

I apologize for my V-8 terminology, it is the flywheel seal.

I believe the surface looks A1, but I will look again and check the size with a micrometer Monday AM. (I did inspect my crank on tear-down, and I measured the bearing surfaces, but I do not recall measuring the end sizes.)

Given the work I've to this engine done it is awful to be stuck on what should be a simple seal....

Last edited by Porsche_monkey; 06-11-2004 at 04:52 PM..
Old 06-11-2004, 04:47 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Author of "101 Projects"
 
Wayne 962's Avatar
Sounds like there might be something wrong with the machining? .004" is a awful lot. Was the case align bored? It's possible that the the case was improperly bored and was offset from the flange with the flywheel seal. This would only show up with an oil leak and a poorly fitting seal, as the other holes are all drilled together.

"On inspection the seal does not appear to be snug enough on the shaft. I could push a thin strip of paper easily between the seal and the shaft."

All the way around the shaft? Or only on one side? It's odd, but your seal sounds too big...

-Wayne
__________________
Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of:
101 Projects for Your BMW 3-Series • 101 Projects for Your Porsche 911 • How to Rebuild & Modify Porsche 911 Engines • 101 Projects for Your Porsche Boxster & Cayman • 101 Projects for Your Porsche 996 / 997 • SPEED READ: Porsche 911 (October 2018)

Check out our new site: Dempsey Motorsports
Old 06-11-2004, 05:40 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Author of "101 Projects"
 
Wayne 962's Avatar
They do make undersized flywheel seals for cranks that have been turned. They are a 1/2mm undersized. What are the dimensions of your crank, and did you use undersized bearings?

The undersized seal is here:

http://www.pelicanparts.com/cgi-bin/ksearch/pel_search.cgi?command=DWsearch&description=90110291100

-Wayne
__________________
Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of:
101 Projects for Your BMW 3-Series • 101 Projects for Your Porsche 911 • How to Rebuild & Modify Porsche 911 Engines • 101 Projects for Your Porsche Boxster & Cayman • 101 Projects for Your Porsche 996 / 997 • SPEED READ: Porsche 911 (October 2018)

Check out our new site: Dempsey Motorsports
Old 06-11-2004, 05:42 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Slumlord
 
Porsche_monkey's Avatar
 
Join Date: May 2001
Location: Canada
Posts: 4,985
When I saw the drips under the car, I was sure that this was a case leak at the joint. I was slightly relieved to see it was the seal. The case was not align bored, and that is now worrying me.

I did a quick check on the crank size with a vernier, then converted on a calculator to mm and I think I was within .001" of spec size, so it does not appear to have been ground.

The paper seemed to slip in only at the bottom, but I can't swear to that. I know when I installed the second seal I was surprised at how little friction there was getting the it onto the shaft. It was snug in the case when I tapped it in.

I don't feel the .004" should be a problem (he said hopefully), the seal should take that ovality up. Even if the crank were 'running out' relative to the case bore I would still expect it to seal for a short period of time, not to leak with-in the first two minutes of running.

Worst case I might have to machine the OD relative to the crank 'in-situ', then sleeve it and re-seal? (I have the facility to do this)

I will have someone from 'QC' do a full inspection and I will repost Monday. I think the ball is in my court right now, but the 1/2 mm seal looks like my next option.

Something is not right, after years of reading this web-site I haven't seen this before.
__________________
84 Cab - sold!
89 Cab - not quite done
90C4 - winter beater
Old 06-11-2004, 07:20 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
Author of "101 Projects"
 
Wayne 962's Avatar
The undersized seal is a half a millimeter larger, so if your crank has been ground, then .001" is a reasonable amount. What is the actual measurement?

-Wayne
__________________
Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of:
101 Projects for Your BMW 3-Series • 101 Projects for Your Porsche 911 • How to Rebuild & Modify Porsche 911 Engines • 101 Projects for Your Porsche Boxster & Cayman • 101 Projects for Your Porsche 996 / 997 • SPEED READ: Porsche 911 (October 2018)

Check out our new site: Dempsey Motorsports
Old 06-11-2004, 10:36 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Ho Hum 74's Avatar
 
Join Date: Jul 2003
Location: Northbrook, IL
Posts: 1,165
Garage
PBH,

I have the same issue on my 2.7. I just don't know what's happening. The first time the seal was pushed out into the flywheel but that was because of an excess pressure build up in the case due to a poorly engineered catch can that didn't vent properly.

I used Curil T on the first one and then left it dry on the next install. I thought there would be more friction without the Curil T. I'm exasperated with this because of all the black flags I'm getting at the track for smoking engine!

I know this is savage but I'm halfway tempted to JB weld the outside of the seal!

Please keep us up to speed on your progress.

Tristan
Old 06-12-2004, 12:07 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Slumlord
 
Porsche_monkey's Avatar
 
Join Date: May 2001
Location: Canada
Posts: 4,985
JB Weld? I'm not quite that desperate. Really close, but not quite. Besides, it won't work. I'm leaking on the crank seal, not on the case seal.

I'm going to post some dimensions Monday AM e.s.t.
__________________
84 Cab - sold!
89 Cab - not quite done
90C4 - winter beater
Old 06-12-2004, 01:27 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
fancytown
 
Join Date: Aug 2002
Location: DEE-troit
Posts: 922
Man this must be contagious! I fired up my rebuilt 2.4T for the first time this Saturday. There are drips coming from the rear of the engine, and so far, all I can see is it might be the flywheel seal. Also, looking at the front, the area behind the pulley appears to be a little wet. I don't see any leaks near the top of the case, and the bottom of the case doesn't leak either. I'm going to pull it to see what's up, but the oil is so clean (now that I changed it), will I be able to tell that it truly is the crankshaft seals, and not the case in that location??

I installed these seals in late December, and wasn't too confident that they were properly seated. I think the Curil-T was hardening from the cold. The front crank pulley seal doesn't have the continuous drips, but the rear flywheel seal does. After further reading, I think this one was pushed in too far. Yes, my seals were all from Pelican. They were part of the Victor Reinz kit.

I'll be paying close attention to this thread, I hope resolution is found!
__________________
1989 Cadillac Brougham
1978 911 SC Targa w/ 3.0L to 3.6L to 3.2L conversion - sold
1972 911T Targa - sold
Old 06-13-2004, 03:47 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
Ho Hum 74's Avatar
 
Join Date: Jul 2003
Location: Northbrook, IL
Posts: 1,165
Garage
Jay,

That sounds like the pulley seal not the flywheel seal. It's a much easier fix.
Tristan
Old 06-13-2004, 04:46 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
fancytown
 
Join Date: Aug 2002
Location: DEE-troit
Posts: 922
I believe they're both leaking. There is a slight wetness at the crank pulley, but alot of dripping coming from the engine to trans connection where the small opening is at on the trans.

I just re-read what I wrote. I always call the flywheel end the "rear". ANyhow, the engine is coming out.
__________________
1989 Cadillac Brougham
1978 911 SC Targa w/ 3.0L to 3.6L to 3.2L conversion - sold
1972 911T Targa - sold

Last edited by Jay Auskin; 06-13-2004 at 06:30 PM..
Old 06-13-2004, 04:55 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Registered User
 
Ho Hum 74's Avatar
 
Join Date: Jul 2003
Location: Northbrook, IL
Posts: 1,165
Garage
Jay,

You and I are in the same boat. I have just replaced mine, now I have to do it again.

I'm going to Curil-T it this time. Any other brain-waves?

Tristan
Old 06-14-2004, 08:47 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Slumlord
 
Porsche_monkey's Avatar
 
Join Date: May 2001
Location: Canada
Posts: 4,985
This is worse than I thought, only a leak in the case joint could be worse. My ovality is more than I thought. I measured the gap between the crank and the case in four positions, data is below;

12 o'clock - 0.399"
3 o'clock - 0.390"
6 o'clock - 0.394"
9 o'clock - 0.393"

The crank measures (by vernier only, no room for micrometer) 2.558", which is 64.97 m, so I think this is standard, not undersized.

So, that means my case dimension vertically is 3.351", horizontally it is 3.341, so I'm 0.010" oval.

I guess the seal is squeezed oval (side-to-side) and this causes the lip to open top-to-bottom, which is how the oil appeared to be leaking out, ie at the bottom of the crank on the lip.

Repair method to salvage a lot of work? I'm planning to put the engine on my boring mill and machine the case round relative to the crank. This should leave me with a bore of .400" all around the crank, that works out to a diameter of 3.358" or 85.3 mm, so I am 0.3 mm oversize and I might need thin sleeve in the case to get the seal tight enough on the O.D.

Anybody got any other bright ideas? I don't lack any tools.
Old 06-14-2004, 11:02 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
Join Date: May 2004
Location: West Tennessee
Posts: 76
I'm kind of intrigued by the JB Weld idea. You could use it to "fill" the case back to round maybe using one of the old seals as an aplicator and it would machine right out the next time you have it apart. It's half-arsed, but who would know?
Old 06-14-2004, 12:16 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Slumlord
 
Porsche_monkey's Avatar
 
Join Date: May 2001
Location: Canada
Posts: 4,985
You would have to make a sleeve that located on the crank OD (65mm) and was exactly 85mm OD, slap the JBWeld on the the case and push the sleeve in. I guess if the sleeve were nylon it could come out after the JB was dry? My guess is it would crack from thermal stress.

I'm going to try and do this by machining my case tomorrow unless anyone can suggest a better idea or a reason not to...
__________________
84 Cab - sold!
89 Cab - not quite done
90C4 - winter beater
Old 06-14-2004, 12:29 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Registered User
 
Ho Hum 74's Avatar
 
Join Date: Jul 2003
Location: Northbrook, IL
Posts: 1,165
Garage
PBH,

Very sorry to hear about your predicament. I very much hope that it’s not the same for me. I did use a different crank this time. I guess the problem you have is that much more difficult to solve in that it is leaking on the crankshaft and not the edges of the seal. Can you not shorten the spring as you suggested earlier?
Old 06-14-2004, 12:45 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Slumlord
 
Porsche_monkey's Avatar
 
Join Date: May 2001
Location: Canada
Posts: 4,985
I found a 0.1 mm tolerance on the Elring web-site for centre-centre alignment. I'm way beyound that as of now.

Hey, at least I have the full machine shop to do it myself without taking the engine apart (again).

Live and learn with the 2.7. If you do not get your case machined you are asking for just this sort of problem...
__________________
84 Cab - sold!
89 Cab - not quite done
90C4 - winter beater

Last edited by Porsche_monkey; 06-14-2004 at 01:04 PM..
Old 06-14-2004, 12:48 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #18 (permalink)
Registered User
 
Ho Hum 74's Avatar
 
Join Date: Jul 2003
Location: Northbrook, IL
Posts: 1,165
Garage
Yes, mine was already line-bored so I'm hoping it was just the outer surface not mating. Let us know how it turns out....sorry couldn't help it
Old 06-14-2004, 01:50 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #19 (permalink)
Slumlord
 
Porsche_monkey's Avatar
 
Join Date: May 2001
Location: Canada
Posts: 4,985
Provided no one talks me out of this I will post pictures tomorrow.
__________________
84 Cab - sold!
89 Cab - not quite done
90C4 - winter beater
Old 06-14-2004, 02:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #20 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 11:40 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.