Lutz and his G50 again, HELP, losing oil again

[lvjost]

The story:
As a few of you know, I had probs with my G50 01 (see thread 6th August)...It was losing a lot of oil....I demounted it thinking its a matter of seals and gaskets I replaced them completely with new....Drove again, again losing oil.....Now new theory by "thevet" shaft bent...so causing the seal to fail...He was right...Demounted gear box again, checked it, shaft was bent....probl. because of pilot bearing....fixed and centered pilot bearing, bulit in a brand new porsche original main shaft (1.350 Euros!) again complete set of new selas...all works done by a guy who worked in porsches gearbox development for 25 years....today i got it back, mounted it again, drove 40 miles....looked....AGAIN AAARRRGGGHH, whole gear box dry, only oil coming out at the top of clutch housing...the hole where you can see a short piece of the starter ring..... I don´t know what to do....3rd time, 3rd repair, new seals, overhauled gear box, checked....AGAIN....

Please Help me verify the following theories or by giving me any advices!!!!

1st Theory, To much oil. I filled 3.5 Litres 75W90 as recommended by ultimasports...To remind you I have
the "short" version, so maybe 3.5 is right for the long ones but too much for the short. It is 15cm
less in length so maybe less volume (?)
1st Pro Argument: The two times I repaired already...I let out the oil and measured...at both times
there were pretty congruent 2.7 Litres left (just coincidence?)...
2nd Pro Argument: I think I remember that I read that porsche oringinally recommends to fill 2.8 Litres.....

2nd Theory, oil gets to hot / depending on speed....
1st Pro Argument: Touched gearbox after driving, was damn hot ! Oil to hot--> gets thin fluid ? and pushes
through the main shaft seal ring
2nd Pro Argument: It semms that it just loses oil if I go over 180 km/h, as i saw the prob today...I
cleaned it, and again drove 25 km accelerating heavily but not exceeding 120 km/h...no new oil!

I´m "fuc#+$ up". Please help me with your experiences...Maybe someone uses the G50 00/01/02/03 with 2.8 Litres or
knows something about the "short" version.....

Venting problems, sela problems, shaft bents...can be eliminated as I already thought about htese things, checked or changed, re-engineered......

I think I´ll let 0.7 Litres out to have 2.8 and try again if there still be oil....Additionally Í mounted a gear box oil temperature sensor and will check the temp...Does anyone knows what temps are "normal" for gearbox oil ?

Thanks for taking your time, to read this book-long thread......

[GTWayne]

I don't know exactly how much oil there should be in the short tail box you have there but I reckon that is where you need to look first and it will cost you nothing. If the guy that built your box has 25 years experience I would be surprised if it had been repaired incorrectly but it is possible??. Have you spoken to the man and sought his opinion?, it maybe a good idea. In normal road use the gearbox oil should not get to hot (typically it should be 100/110 degrees) and I would be amazed if it was to be forced past a seal as a result. I am willing to bet that because this problem has occurred more than once already and has cost a bit you are automatically expecting something nasty (it's human nature) but don't dismiss the simple possibilities and look to deeply at more complex causes. Hope you get sorted, let us know what it is, W.

[canam-phil]

Sorry for asking but you do have the transmission breather-type tank fitted don't you?

[lvjost]

Wayne: Thanks, I´ll keep you informed....

Phil: Yes, I´ve fitted it AND I constructed a reducing bush which reduces from 22mm to 14mm and with this I fitted the original (developed by porsche for this gear box) breather bolt (the one ultima welds and silikons because they turn the gear box up and down)...And I´ve tested it by blowing air with a hose into a side hole and it perfectly came out at the top at my new / additional breather bolt.... I think this can´t be a source of error, except I overlook smth.,what is your idea ??

[thevet]

If the gearbox was dry after your first run it does suggest a large leak somewhere. Try the obvious first- any bolts left out or loose, or any breather pipes loose or upside down? Where is the oil leaking from this time? If necessary take the box off the engine and check the seal again by tipping the box up vertical on a bench and look for oil seeping from source. Even when my main shaft seal failed I didnot get anywhere near a dry gearbox, so I doubt it is just a main seal. Check the shaft again as it is not clear why it is bent, maybe there is another cause for the bend other than the pilot bearing. Find out where the oil is coming from and then work out why, sounds easy but it was a pain for me to sort as putting the gearbox on and off again and again was hard work and worse when my attempts to fix it failed several times.

[mkoch1]

what about cleanning the box up, taking the back of the car off and putting the car on a dyno. Might be able to see where the oil is comming out of the box.

mark

[ditto]

I have a short tail box in mine and I put 3.5 litres of 75W90 with no problems, so sadly I dont think its to much oil
I hope you get it sorted
Keith

[andygtt]

The bent shaft and repeat of the oil leek at the clutch sided leads me to ask if you have checked the gearbox is mounted true to the engine.

[lvjost]

to thevet: I know how frustrating it is to mount and demount a gear box a dozen times, can really
feel with you..!

to mark: Very nice idea basically... but I do know where the oil comes out. It is the hole on the
upper side on the clutch housing, where one can see a short piece of the starter ring, if this is
mounted on top, not at the adapterplate-side of the flywheel...That means, that the leakage
must be somwhere insinde the bell housing, the shaft seal or a fissure of the gear box housing...
You can´t see smth. there when the gearbox is mounted...so the dyno doesn´t work in this case

to ditto/Keith: Damn, that was one of my hopes...But thanks for helping me eliminating this source of error
Could you help me by sending me some pics of your gearbox of your breather construction...

to andygt: What do you mean with your question ? Not mounted "true to the engine" ? Do you mean, that
the main shaft doesn´t reach the pilot bearing ? or what ? Please explain to me...

[canam-phil]

If its coming out as you describe, then you must loose the clutch to oil contamination as it must cover/spray the parts inside the bellhousing if its coming up as far as the top aperture.

It is definitely the green transmission fluid is it? I just cant see any way this happens as I thought the normal oil level was lower than the transmission shaft. (May be wrong about that though)

If I'm right about the oil level then the oil seal on the shaft is only coping with slosh/spray and unless the case is pressurised, I cant see oil coming out quickly.

Can you confirm that the oil is the green transmission fluid AND the tranny side of the flywheel housing is covered in oil both above and below the centre of the tranny housing?

Any pics?

I had a leak due to a muppet overfilling the tranny but that meant the oil came out of the breather tank.

Phil

[thevet]

Lutz, if the oil is coming out of the bellhousing then you need to find out where. Is it around the shaft? or is there a crack or hole it is escaping through, inside the face of the bellhousing? Oil spraying from the bellhousing happens because there's a gap for it to come through by the starter ring, but how did it get out of the box? I still have to say check the box when it is off the car, and filled with oil. I'm worried that you say the gearbox was dry, as the shaft leak and oil coming from the bellhousing only lost me a litre of oil: I measured how much had come out, when I drained the box. Have you checked the shaft seal since replacing and looked to see if oil comes past it when the box is vertical? I can't quite see how the pilot bearing for the shaft can be out of line if you have a correctly made adapter plate, so how could this cause your shaft to be bent!!!!![does this have the same implications in German as it does here?] It cost me a couple of months and and new box to sort the problem, so I wish you better luck than I had.

[ditto]

Here are the pics you asked for Lutz, im not sure if they are going to be of any use, as it’s a standard factory set up
I also agree with Phil, if the box was over filled it would come out of the breather
Keith

[andygtt]

lvjost said:

to andygt: What do you mean with your question ? Not mounted "true to the engine" ? Do you mean, that
the main shaft doesn´t reach the pilot bearing ? or what ? Please explain to me...

what I mean is check the pilot bearing in the crank exactly aligns with the output shaft on the gearbox when mounted.
I'm sure it does align but if it's slightly out oil could come out of the seal at the front of the gearbox regardless of how well it's built.

[shithotfast]

yep I had that. If the pilot bearing has come out, or moved back into the flywheel - the end of the shaft wont sit in the bearing and the shaft will "flop" about, only a bit of course, but it then wears the end rubber oil seal and oil can come out when the box is active.

My pilot bearing had pushed back into the flywheel. trouble is its one of those funny ones....... bit like closing the fridge door and seeing if the light has gone out or not. When you mount the gearbox it can push the pilot bearing out, but you wont know until you remove the gearbox to cheak.... then you put it back again etc.

I glued the pilot bearing in place just in case.

[GTWayne]

Might it not be a good idea to get a new longer bush turned up out of phosphor bronze or something? it wouldn't cost much.

[lvjost]

For the time being good news... I drove again yesterday to do severeal tests, to eliminate a few maybe-sources...I drove 4 h, 130 miles and did a few times far over 160 mph (I love germanys unlimited highways :-) ....I checked the gearbox several times, and there was no new oil coming out...So maybe a friend of mine was right with his theory of a bit of dirt between the main shaft and the new seal ring from the assembly, which was rinsed by the oil I´ve seen...and now is clean and dry...I HOPE SO !!! Thanks for all your help and advice(s). i´ll let you know, if there will be oil again....

[GTWayne]

Good luck and if anything positive is to have come from this experience, it is that you have boned up on your English a little!

[steve_d]

GTWayne said:

Might it not be a good idea to get a new longer bush turned up out of phosphor bronze or something? it wouldn't cost much.

The bearing should be made from a material called 'oilite' It's sintered bronze with the gaps in the grain structure impregnated with oil.

Would have thought a bearing with a small shoulder would do the job.

Oilite bearings are in Ipswich.

Steve

[ditto]

steve_d said:

GTWayne said:

Might it not be a good idea to get a new longer bush turned up out of phosphor bronze or something? it wouldn't cost much.

The bearing should be made from a material called 'oilite' It's sintered bronze with the gaps in the grain structure impregnated with oil.

Would have thought a bearing with a small shoulder would do the job.

Oilite bearings are in Ipswich.

Steve

I used a standard chevy bearing first then fitted the one supplied by the factory, which stops it being pushed in to the back of the crank when fitting the box

Keith

[GTWayne]

ditto said:

steve_d said:

GTWayne said:

Might it not be a good idea to get a new longer bush turned up out of phosphor bronze or something? it wouldn't cost much.

The bearing should be made from a material called 'oilite' It's sintered bronze with the gaps in the grain structure impregnated with oil.

Would have thought a bearing with a small shoulder would do the job.

Oilite bearings are in Ipswich.

Steve

I used a standard chevy bearing first then fitted the one supplied by the factory, which stops it being pushed in to the back of the crank when fitting the box

Keith

Not just a pretty face then eh Keith?