Question on oil seals/leaks

[1970_Pete]

I'm considering the purchase of a 1973 2.4s - the only thing the inspection shows up is that there is a minor oil leak from the rear crankshaft seal and also from the gear selector seal where it goes into the front cover of the gearbox. I understand that the crankshaft seal can be replaced with the engine still in the car (remove pulley first) but don't know about the gear selector seal - please can anybody help with advice?

Thanks
Pete

[Jim Sims]

Both the shifter seal and the crankshaft pulley end seal can be changed with the engine/transmission in the car. How do you know that the pulley end leak is the crankshaft seal? It could be the case joint sealant or the o-ring on the outside of the no. 8 nose bearing. The back engine mount/console has to come off to access this area for a proper evaluation. Was this done? The proper repair for these leaks requires cracking the case but provisional repairs have been made for the o-ring leak by cleaning (carefully degreasing with brake cleaner or equivalent) the area outside of the nose bearing and making a fillet of RTV silicone rubber in the corner to affect a temporary seal. Be wary. Jim

[1970_Pete]

Thanks for the quick reply Jim.

In answer to your question, about the crankshaft seal - the situation is as follows: I live in the UK and have had the car inspected by an official Porsche dealership 300 miles from me, in a location convenient for the vendor. This evening I got the briefest of details faxed to me saying "oil leak from rear main seal". I'm very grateful that you've pointed other potential causes, but let's hope the official Porsche mechanic correctly identified the source..!! I'm hoping to get more details tomorrow.

BTW, any idea how long it would take the average Porsche shop to replace the rear seal? I'll look parts costs up here, but if you know a ballpark figure, I'd sure appreciate it.

Thanks once again,
Pete

[Superman]

I think you're looking at the wrong seal. The wrong end of the engine. "Rear main seal" is a pretty specific term in motoring, and it means the seal next to the flywheel. Technically, the "front" of our engines is the end that is nearest the rear bumper. Rear mains seals do have a habit of leaking. Finally, I'd rather have a leaking rear main seal than a leaking nose bearing o-ring, since fixing the former does not require splitting the engine case.

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'83 SC

[Jim Sims]

Here is approximately what the job entails assuming there is not an air conditioning system: remove muffler (silencer), jack and support engine, remove back sheet metal tray piece, loosen engine mount bolts and remove engine mount crossbar and console. Remove fan belt, loosen crank pulley bolt and remove pulley. Extract old seal; this is the real trick. Install new seal preferably with the correct seal installer tool. Then reassemble in reverse order. I don't know what the dealer "booktime" is (John Walker may know) but I could likely do it in four hours including some cleaning. Potential problems that require more time: badly corroded muffler flange joint bolts (I'd install new gaskets at these joints as a matter of course) and muffler strap bolts plus getting the old seal out. Also, the sealing journal surface of the crank may be worn from years of rubber and grit wearing on it so simply installing a new seal may not cure the leak. The method for removing the seal that my mentor taught me was to carefully drill (an air powered drill motor works best as it has better control than an electric one plus a bit of tape wound on the drill bit to limit depth of penetration) two very small holes through the metal portion of the seal opposite each other. Then screw in a couple of small sheet metal screws. Attach small vise grip pliers to the screws one at a time. The vise grip pliers are modified to work with a slide hammer. Work side to side and the seal just pops out. There is no digging or gouging. Vacuum out any bits from the drilling and install the new seal.

[Jim Sims]

If it is the flywheel end seal (why isn't this terminolgy used!) then the engine has to be dropped and the flywheel removed. The worn sealing journal caution applies here too. Given the shifter end seal leak I'd drop the whole engine/transmission assembly and work on it like a gentleman. This means more time, parts (CV joint flange seals, flywheel bolts, etc.) and potential problems (frozen oil line fittings, stuck flywheel bolts, and maybe an oiled clutch disk but not likely). My '76 is going down this winter for this very repair plus an auxilliary oil cooler installation. Cheers. Jim

[Fishcop]

"Rear Main Seal" is the one between gearbox and engine. The rear of an engine is the end that mates to the gearbox regardless of the engine/gearbox configuration or location.

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John Forcier
69 911T

[1970_Pete]

Thanks guys, you've all been so helpful. I feel much better equipped to decide whether I want to buy this car or not. I'll see what tomorrow brings when I (hopefully) get more feedback from the inspection.

Cheers
Pete