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77 turbo-oil leak, not the usual suspects?
Comlpeted my first engine drop, solo, on a '77 911 turbo...
thanks to all for the great info posted here. Now to the problem... the reason I dropped the engine was that I had oil leaking from the bottom of the transaxle in the area under the axle flanges. It appeared to be coming down each side from the top. The oil in question did not seem to have the charactaristic smell of gear oil. After some online research I figured it was probably the usual suspects... thermostat o-ring, breather cover gasket/hose, oil pressure switch, etc... and the oil was working its way from the top to the trans and leaking from there. Plus the fact that I wanted to do some cleaning up and replace the sound pad, etc... more of the usual stuff. Time for an engine drop. So, I gathered all the replacement parts I thought I would need and proceeded to drop the engine. Now that the engine is out, I don't see any signs that the oil was making its way from the usual suspect's area on top of the motor to the trans and down the sides....? Pictures are posted below... Now I am questioning whether or not it actually is engine oil. My nose doesn't work so well after 25+ years of painting, and I am wondering if this isn't in fact tranny oil. I don't know what type of oil the previous owner used, does synthetic gear oil have that awful stench that dino gear oil does? During my online research I saw that the vent on top of the transaxle should face forward, is this correct? Mine does not. You can see in the pictures that there is oil on top of the trans, and not a lot on top of the engine. More importantly I don't see any path of oil between the top of the engine and the oil on the trans... Am I looking at leaking transaxle seals? The back sides of the axle flanges look dry... Any advice would be greatly appreciated...        
Last edited by zentoad; 04-13-2007 at 05:18 AM.. |
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04-13-2007, 05:13 AM
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update...
Just did a lot more reading about the transmission vent on this site. I've included another pic which shows the orientation of the vent as I found it.
 At first I didn't think that the amount of oil on top was enough to produce the amount of oil that was leaking off the bottom... But, after reading endless times about how the vent needs to be facing forward, within the 90 degree arc, I am beginning to believe that this is my problem. I guess that the oil on top is spread throughout all the grime and grunge up there, kinda like water being absorbed into the sand on the beach? Also, the car has been sitting and I assume that by now the oil has found its way by gravity off the top and onto the garage floor. Any agreement on my observations? What has me baffled, and the flaw in my diagnosis, is why wasn't this leaking before? The lack of smell to the oil bothers me as well, but the picture above shows no oil flowing over the bellhousing from the top of the engine.... HMMMM Well, in the meantime, I wil press onward... Last edited by zentoad; 04-13-2007 at 12:04 PM.. |
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04-13-2007, 09:30 AM
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I'm thinking it is from the vent but is it possible that you have a pin hole leak on this line?
 Is that even an oil line?
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Glenn Daily Driver - '78 911SC RoW Endurance Racer - '85.1 944 Street/Track Project - '86 951 Race Project - 944 Spec |
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04-13-2007, 12:14 PM
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It's the trans vent. If it were the T-Stat O-ring, temp sensor, etc. there would be a puddle on top of the engine or it would be wet. The top of your engine looks dry. The fluid is to high on the trans to be from the trans output shaft seals.
Hope this helps, Shawn |
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04-13-2007, 01:37 PM
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oil collects on spinning objects and gets tossed outward. Looks like the output shafts are leaking and oil is getting onto the CV joints and flying out from there.
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04-13-2007, 02:55 PM
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Quote:
I didn't post a good picture of it but the insides of the axle flanges appeared to be dry. I assume the the oil would have to travel over the flanges to get to the CV joints. Was that what you were referring to? There was some spinoff of oil onto the underbody of the car, but it appears old and dry... not the wet appearance of the oil on top of the trans. Shawn I fully expected to find oil puddled on top of the engine, I bought all the gaskets and seals to deal with that... Of course I will replace them "while I am there" anyway. I agree that the vent is the most likely possibility, I just don't understand why it started so suddenly. The vent seems to have been in the wrong position since the car was purchased, when I corrected the position it was very tight. Glenn I did a quick check of the line you indicated -a very interesting possibility, I could envision that happening- but, running my fingers over line produced only dry grime... not a drop of oil to be found. I've read quite a few posts about oil leaks, too many for comfort, in which people had to repeatedly drop their engines to correct them. I am hoping to avoid that. I am considering adding dye to the new gear oil, just in case. Spent about 4.5 hours cleaning the trans today... hopefully I won't neeed that nice clean surface to diagnose the leak a second time around.... I appreciate the input guys, Thanks, Tony Last edited by zentoad; 04-13-2007 at 07:39 PM.. |
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04-13-2007, 07:36 PM
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When I had my engine out a few months back, I took the opportunity to change the tranny fluid. Assuming you use Swepco, you will find that it has a unique color. When you see it, you will know it is not engine oil.
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Glenn Daily Driver - '78 911SC RoW Endurance Racer - '85.1 944 Street/Track Project - '86 951 Race Project - 944 Spec |
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04-14-2007, 02:37 AM
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Of course Glenn, that was the plan,
I guess I would have realized at some point that I wouldn't need the dye.... But who knows, with the other weighty issues on my mind, I probably would have missed it. Thanks for reminding me. Tony |
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04-14-2007, 08:29 AM
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JOT MON ABBR OTH
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Glen,
I don't remember a high pressure oil line through that area on my SC, but it is NA not turbo. Is that a high pressure line you have annotated? Zen, I would go forward with replacing all the likely suspects, it is insurance for the future. I would see if you could pressure test the line highlighted or identify if it is an oil line.
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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. |
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04-14-2007, 08:39 AM
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Quote:
Zen, is that a turbo related oil line?
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Glenn Daily Driver - '78 911SC RoW Endurance Racer - '85.1 944 Street/Track Project - '86 951 Race Project - 944 Spec |
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04-14-2007, 12:38 PM
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Quote:
-oil tank to turbo oil pump- The link below ( I think)shows the line in question on a 78+ parts diagram on our hosts web site, the 77 diagram doesn't seem to match... http://www.pelicanparts.com/cgi-bin/PartsLookup/search.cgi?command=show_page&Catalog_Name=911_USA_78_83_KATALOG&Illustration=107-40&Line_Item=40 I think I am going to take a real close look at that line next chance I get... and pressure test it I knew I disconnected it from the oil tank, but until now I paid no attention to what it was connected to! Glenn, I can see that line in my imagination spraying oil in a nice arc, over the bell housing and onto the top of the transaxle... If that turns out to be the case, I will owe you big time! |
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04-14-2007, 07:33 PM
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I wouldn't rule out the flywheel seal. I had the same nagging leak and oily film in the same locations. Top of the engine was dry. A drop of oil hung from the bottom of the new oil cooler. The oil would drop onto the lip of the right heat exchanger and roll forward leaving a drop of oil on the garage floor. Everything pointed to the oil cooler. It was pressured tested and found to be good. There was no leaking from the oil cooler seals. Parting the engine from the trans exposed the leak. We replaced the seal using the 'shortening the spring 'method and so far so good.
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Peace, Ron www.ronorlando.net 78SC Targa 3.2 SS, 964 cams, CIS, SSI's,Dansk Own a gun and you can rob a bank , own a bank and you can rob the world. |
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04-15-2007, 06:19 AM
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Good thought Ron. That would have been one of my other guesses.
Any plans to split the engine/transmission, Zen?
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Glenn Daily Driver - '78 911SC RoW Endurance Racer - '85.1 944 Street/Track Project - '86 951 Race Project - 944 Spec |
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04-15-2007, 07:01 AM
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I've already split the engine trans...
In my non-expert opinion the flywheel seal is not the culprit. There was a buildup of dust caked with oil(?), sounds bad right... but it was mostly dry. I trying to think of how to explain it.... it was almost like a layer of dust over grease... Is that what a leaky flywheel seal looks like? I am new to Porsches But, and here is what I based my decision on, it was nowhere near the amount of oil that was dripping off the trans... The pictures don't really give an acurate depiction of the amount of oil on sides of the trans. Anyway, I have the flywheel seal and was planning on replacing it anyway... What is the "shorten the spring" method? I can almost guess, but where would I find the procedure? Gotta run now... more to follow |
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04-15-2007, 12:32 PM
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Trans flange seals would leak on the backside of the flange, not where the bolt goes. What did the pressure plate, clutch disk look like? A leaky flywheel seal, or trans mainshaft seal would most likely leave them wet.
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04-15-2007, 02:26 PM
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Donnie,
The backsides of the axle flanges were dry, my earlier post may have led some believe that I was referring to the flange central bolt area... I will know tomorrow about the condition of the pressure plate/clutch Thanks again to all for your input and interest Last edited by zentoad; 04-15-2007 at 04:07 PM.. |
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04-15-2007, 03:54 PM
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Quick update...
Going with the idea that the trans vent is the culprit, will confirm at later date. The clutch and flywheel look fine and dry. "While the engine is out", I am waiting on a bunch of gaskets and seals... plan is to powdercoat tin and fan, paint heat exchangers-exhaust-shroud, replace heat pad etc. etc. etc... |
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04-26-2007, 11:01 AM
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Quote:
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Glenn Daily Driver - '78 911SC RoW Endurance Racer - '85.1 944 Street/Track Project - '86 951 Race Project - 944 Spec |
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04-26-2007, 12:00 PM
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long overdue update
just a note to confirm the outcome...
the oil was indeed coming from the transmission vent. no leaks since re-install. |
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11-06-2008, 12:52 PM
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"The Porsche"
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'74 Porsche 911 2.7
