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Join Date: May 2004
Location: Tallmadge, Ohio
Posts: 78
Newbie Questions- Leaks & Seals

Hi All!

I am the new owner of a '72T and am looking forward to trying out a 911 for a change from my Tiumph TR8. While the 911 runs well it leaks tremendously from every typical spot. I am going to pull the motor & trans & reseal everything short of splitting the cases. This brings me to my questions.

Do 911's use valve seals? The motor runs great but blows a fair bit of blue smoke on a hard overrun. My thought was valve seals. It puffs just a bit on start up but not during normal or even hard driving. Only on a hard overrun, throttle full off & in gear. Occasionally a small puff between shifts noticeableonly if I am observing from outside the car. Since I am going to install 'E' cams & have to shim the valve springs to spec anyhow I thought seal replacement would be good as well. Has anyone used one of the compact "on the motor" valve spring compressors with success? If I can get the compressor arms on the spring at the top I figured i could "screw" it down into the valve spring counterbore to effect the compression.

My second question is can the cases be split without head removal? I have a localized leak of the case joint. If not I am thinking of trying to seal the leak without splitting the cases. I have done little research on wicking sealers & the plan is this:

Since the motor is out of the car turn it over. Clean it (and the entire motor) throroughly with solvents. Draw a vacuum in the crankcase and hose down the leak area under vacuum with solvent which should remove oil from the leak path. (The motor will be flushed before restarting and this will likely be a very small amount of solvent). Allow all to dry under vacuum. Apply wicking sealant to the leak area with the crankcase under vacuum, let dry, repeatedly. Then pressurize the crankcase & check leak area with gas line leak detector.

Yeah, I know I am crazy, but I have done a lot of things that "can't be done". I would settle for a once a week drip as opposed to a couple drips a day.

If any knowledgeable list members live near Akron, Ohio look me up.

Thanks,

Bill McCauley
triplesn8s@neo.rr.com
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Bill McCauley
'72 911T Coupe
'80 TR8
'78 TR8
'75 Jensen Healy
'00 Triumph Sprint ST 955i
Old 07-19-2004, 08:44 AM
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JOT MON ABBR OTH
 
Groesbeck Hurricane's Avatar
 
Join Date: Feb 2001
Location: Tulsa
Posts: 3,189
Welcome Aboard!

I would suggest copies (purchased from our host) of the 101 book, engine re-build manual, and the Haynes (I'm going to be flamed for that one ).

911's do use valve seals. This might be the cause for the smoke. I do not know if you know how to check oil in a 911 but you need to allow the motor to warm up, park on a level surface, and check the oil level with the dip stick while the motor is warm and running. The guage in the dash is just for show. Too much oil in the car can also cause smoking. My valve guides were on the high side of the spec at the re-build and I left them. They are my most likely culprit for smoking on start-up when cold.

If you are going to redo the cams I would suggest taking off the entire valve train and inspecting the valves for wear. This will expose the Pistons and Sleeves and allow for inspection without removal. Be sure to keep your motor covered so no dust or dirt or little buggies can get in it...

My understanding is that you should remove everything if you are going to split the case.

If memory serves, others have not had much luck with wicking sealant. FWIW.

There are several anciliary parts on the top of the case that should be replaced (oil pressure sending unit) and many locations with seals that might have gone bad over time. This is a fairly inexpensive set of fixes and I would highly recommend it.

Best of luck,
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David
'83 SC Targa (sold ) MANLY babyblue honda '00 F250 7.3L (MINE!)
'15 F250 Gas (Her Baby) '95 993 (sold )
I don't take scalps. I'm civilized like white man now, I shoot man in back.
Old 07-19-2004, 10:44 AM
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Registered User
 
Join Date: May 2004
Location: Tallmadge, Ohio
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David,

Thanks for your reply. I have really only driven the car once, about 50 miles home from where I bought it. I think the PO said he might have had too much oil in it. It leaks so much it was "Fill up the oil & check the gas."

The motor appears to run well now so I am reluctant to pull the heads. It has ~ 95K original miles. If I have to I will. I am going to examine it thoroughly before I make any final decisions.

I figured that wicking sealers have been tried. I was wondering if anyone had tried pulling a vacuum on the crankcase in the process to aid cleaning & the wicking action. I was counting on the fact that I would have the motor drained, upside down pulling a vacuum to keep used oil from contaminating the sealing surface & sealing agent.

I have all the books & am going to put new seals everywhere. I just hate to leave a case drip after that kind of effort. But not as much as i would hate to have to split the cases at this point ion time. I've got young children & too many major projects in process right now.

Thanks again,

Bill
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Bill McCauley
'72 911T Coupe
'80 TR8
'78 TR8
'75 Jensen Healy
'00 Triumph Sprint ST 955i
Old 07-19-2004, 11:09 AM
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JOT MON ABBR OTH
 
Groesbeck Hurricane's Avatar
 
Join Date: Feb 2001
Location: Tulsa
Posts: 3,189
Bill,

One other thought on the vacuum process. What happens if the sealer wicks into the motor? Loctite 574 only hardens in the absence of air, other sealers harden in any environment. Could some sealant get into the motor, harden, and then play havoc on your oil delivery or cause other damage? I don't know, just thinking...
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David
'83 SC Targa (sold ) MANLY babyblue honda '00 F250 7.3L (MINE!)
'15 F250 Gas (Her Baby) '95 993 (sold )
I don't take scalps. I'm civilized like white man now, I shoot man in back.
Old 07-20-2004, 05:36 AM
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Friend of Warren
 
Join Date: Oct 2000
Location: Jefferson City, MO
Posts: 15,524
Bill, welcome to another British Car masochist! While your idea of a wicking sealant sounds good, in practice I don't think it will work. I don't think, with all the places you would have to plug on a 911 case, that you could ever draw vacuum. Where is the case leaking? If it is the bottom seam I have used a Dow aircraft sealant ($74.00 at tube) that will actually seal the oil leak.
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Kurt
2003 Boxster S, 1991 BMW 318is
'93 Ducati 900SS, '76 BMW R75/6, '73 350 Honda Scrambler, 2003 SV650 Track bike

Gone, but not forgotten: '86 Carrera, '72 911E, 2001 Boxster
Old 07-20-2004, 06:07 AM
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Join Date: May 2004
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Dave,

I see your point but I am not worried about a couple of drops of sealer in the crankcase. I am assuming the only surfaces that have any chance of being clean are the ones sucking the cleaner through, the gap. Any other cleaner or sealant running through will be contacting oily surfaces and immediately diluted. I ass u me.

Kurt,

Yes, the leak is at the bottom-front of the crankcase. How thick is the aircraft sealant? Got a number? I was not too worried about generating a lot of vaccum with the wicking sealant just enough to encourage the wicking. I thought a shop vac and a "good enough" sealing job on the motor would work.

Might have to suck harder on the Dow assuming it is thicker. More sealing issues & potential contamination from other leaking areas, unless I seal everything else first. I know, I will overkill it like I always do and use both!!

You have no I dea the masochist I am, '75 Jensen Healy "gonna be a racecar but babies intervened" mid-rollcage, 80 TR8 Convt nice driver modded suspension there & big brakes in the works, 78 Pre-production TR8 Coupe awaiting suspension & motor work (have parts), 3.5 liter 225 HP under construction and I can't decide which car to put it into.

Oh man, why do I have to work? I would be such a good rich guy. I wouldn't sleep in or be lazy when there are so many cars & so little time.

Thanks for your input guys and thanks to Wayne for supporting such a nice, friendly forum.

Bill
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Bill McCauley
'72 911T Coupe
'80 TR8
'78 TR8
'75 Jensen Healy
'00 Triumph Sprint ST 955i
Old 07-20-2004, 06:57 AM
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fancytown
 
Join Date: Aug 2002
Location: DEE-troit
Posts: 923
Bill, with all the leaks you have, the case might not be leaking, it just might appear to be. The front leak might be the crankshaft seal, or t'stat, or oil pressure sensor leaking. A leak from the front top will travel right down the middle seam of the case.

The rear seal could be the pulley side crankshaft seal (repairable), or the nose bearing (not repairable w/o splitting case). I would suggest fixing all seals you can w/o splitting the case. You might have a few weeks worth of work with seal replacement, but with splitting the case, you're getting into months. Once you split the case, the cost will go up signifiacntly, as you truly might as well do a full rebuild.

Glad to see you bought the best year 911 ever made!!!
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1989 Cadillac Brougham
1978 911 SC Targa w/ 3.0L to 3.6L to 3.2L conversion - sold
1972 911T Targa - sold
Old 07-20-2004, 08:54 AM
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Friend of Warren
 
Join Date: Oct 2000
Location: Jefferson City, MO
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Here is the stuff. It is fairly thick, like gasket sealer. Will not wick into the case seam, but if you clean the outside of the case seam well, it will get the job done.

"DOW 730 SOLVENT RESISTANT SEALANT
A one part RTV paste which cures at room temp. to a tough rubbery white solid. Used for bonding, sealing and caulking where resistance to fuels, oils and solvents is required. Excellent on fuel line pipe threads, repairing fuel lines and tanks, bonding components exposed to fuels, oils & solvents. temp. range -85F to 400F. Stores refrigerated for years.
09-00383 DOW 730 SOLVENT RESIT SEALANT $79.85" http://www.aircraftspruce.com/catalog/appages/dow730.php
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Kurt
2003 Boxster S, 1991 BMW 318is
'93 Ducati 900SS, '76 BMW R75/6, '73 350 Honda Scrambler, 2003 SV650 Track bike

Gone, but not forgotten: '86 Carrera, '72 911E, 2001 Boxster
Old 07-21-2004, 12:32 PM
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Join Date: May 2004
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Thanks guys.

Kurt, I am going to order some of that sealant today. It sounds like its the bomb.

Bill
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Bill McCauley
'72 911T Coupe
'80 TR8
'78 TR8
'75 Jensen Healy
'00 Triumph Sprint ST 955i
Old 07-22-2004, 06:28 AM
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Join Date: May 2004
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Talking

For the benefit of the Forum members I found the Dow 730 Sealant at my local Bearing Distributors Inc. for $59.99. Their number is 330-498-4980.

Bill
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Bill McCauley
'72 911T Coupe
'80 TR8
'78 TR8
'75 Jensen Healy
'00 Triumph Sprint ST 955i
Old 07-22-2004, 06:48 AM
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