QuestionQUESTION: I have owned this 928 for 18 years and it has been leaking transmission fluid around the pan gasket all that time. I change the fluid and the gasket, checking the pan and seal and all seems perfect. It seems to be an issue of gasket seal. The car has 40,000 miles, runs well but has the trip leak. The car has sat for weeks at a time over this 18 year period.
Any suggestions?
Thanks
ANSWER: I owned three 928's, 78 manual, 84s automatic and a 89s4 automatic.
The automatics were great cause I did not spill my coffee as often when driving to work.
On the auto trans leaks, here are some come culprits:
ATF cooling lines at the connection at the radiator.
On pan leaks, when you remove the pan you have to clean the contact
surfaces well and dry them. The gasket is installed without sealants.
If you fail to torque up evenly, starting with finger turns and then progressing to the torque wrench, you could distort the pan and that will be sight for leaks.
A word has been said about low fluid levels leading to overheating and expansion or the fluid to escape out a check valve? I have not verified this.
I believe the reservoir may have a min and max line, as well as a marking of "20" and "80". These numbered marks are the "fill to" marks based on the temperature, hence you would fill to the 20 mark when the temperature was 20 C and the 80 mark when the temperature is 80 C. So if you have too much fluid it expands and you get overflow.
Verify what your shop manual or owners manuals specifies.
My 84s leaked by the resv. tank.
Hope these tid bits help.
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QUESTION: I agree with everything you've said. You can overfull which leads to over pressure in the reservoir. The pan design is poor. The pan has a rounded lip, the gasket fits over it and press fits up to the pan housing and than tightened, but not over torqued. That can distress the gasket. Weird design. The pan would have been a better seal if two flat areas met for a seal with the gasket between.
ANSWER: I realize the amount of torque for the pan bolts is rather light, however have you tried going back and re-tightening the bolts after the leak appeared; depending upon the type of gasket material or composite used by the gasket mfg. a material that does not have memory will compress and remain in that state. As the transmission expands and contracts a material with less memory will leave a gap. So, if you have not tried re-tightening give it a shot and see if the leak reduces and if so retighten it again.
Another possibility, beside material type or brand type of gasket, whether OE or aftermarket, is supersession (example a new part number).
The PET shows a new part number for the gasket, and possibly a different part number for the pan. OE's are not always 100% perfect on changes so there could be an issue with respect to gasket configuration of what fit before vs. what you might have used for a replacement if OE. So this is an area to explore.
Let me know how you make out with these to suggestions to explore.
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QUESTION: I'm not familiar with PET. Can you explain?
Thanks
AnswerPET is Porsche Electronische Teile
Most of us have this proprietary parts diagram on disk.
Don't know the copyright status on the disk version,
however this link is free and is a pdf version so you may
want to save it as a file to your hd:
http://www.porsche.com/usa/accessoriesandservices/classic/genuineparts/originalp
