paalw

I am in the middle of a big round of maintenance. I have already done the interior, replaced all shocks, gearbox oil, spark plugs, MAF, and brakes. What is left is the following:

*Timing belt/waterpump, including Porkensioner install
*Oil sump gasket
*Steering rack bushings
*Fuel lines
*Motor mounts ****Added with edit, forgot it first time****

I like the idea of finishing one job before starting on another. I have never done any of these things before, but I have a feeling I would benefit from doing some of them together, or at least in a specific order.
Any tips before I begin from those of you with experience would probably be very helpful.

95carrera

I suggest you do the fuel lines first. Waiting could kill you or destroy the car. After that I would make sure all the vacuum lines are functioning then I would do the belts.

paalw

I am doing everything while the car is on a lift. No driving in between.

worf928

Rack bushings are a WYAIT when doing the oil pump gasket and motor mounts. You ARE doing motor mounts right?
Fuel lines should be done last. That way you will not lose track and forget to test the fuel system for leaks by bypassing the fuel pump relay before you start the engine.
Do not skip the leak test. Ever.

Mrmerlin

1 and 4 can be done together , then check for fuel leaks then a run test.
2 and 3 can be combined and add in motor mounts

StratfordShark

There’s no particular order for those four, but you’re already doing most of the work involved in new motor mounts when removing crossmember for OP gasket, and you’ll have the rack lowered so replacing bushes is very little extra at that point. So combine bushes and gasket, and don’t hesitate to change mounts (makes huge difference if old ones collapsed)

paalw

Yes, I had the feeling I forgot something on that list. I am changing motor mounts too, already have them ready from Roger.

So if I understand most of you I can divide this work into two major jobs:

1. motor mounts, pan gasket and rack bushings.
2. TB/WP/PKT and fuel lines.

Any suggestions who of those two to begin with?

Mrmerlin

I would do #2 first, dont do a run test till after all the work is done. Since the alternator will be off
work from the top down,
that way the oil pan will be clean in the front when you go to remove the bolts,
as you will have cleaned the front of the engine to fit a new belt and pump and the alternator cassette will be off

Wisconsin Joe

The TB/WP ect will mean spending a lot of time bending over the motor, reaching down.

The MM/OPG ect will mean spending a lot of time on your back reaching up.

Which way do you want to be sore first, which way last?
Not a whole lot of other reasons to do one or the other first.

BUT...

There are a couple "disassemble to get out of the way" things common to both jobs.
The alternator and dipstick are the two that come to mind, there are likely others.

Read through the procedures and understand what goes on with both jobs. No point in removing, installing, re-removing and reinstalling stuff.

Dwayne's writeups on both jobs are excellent. (Captain Obvious, at your service)

hacker-pschorr

With the timing belt job, I would do the camshaft, crank, and oil pump seals.

Any thoughts on the cam chain tensioner or at least the pads?

worf928

hacker-pschorr

I dunno, the full time mechanics I know who do nothing but European cars will never to a TB/WP job on any car without doing all the front seals. Too many stores of customers insisting they be skipped to save money, only to return within the next year with something leaking.

If your 928 is up to date & on a 5-6 year belt schedule, maybe.....
Unknown history and getting everything up to date like the OP is, personally I would do them (and did on my 87)

However, this does bring up an issue form another thread discussing some seals are better quality than others when installing.

worf928

This makes sense at first blush. But...

... I'm pretty sure that I have a large-enough sample size to question these WYAIT seal replacements.
I've done several belt jobs on untouched-since-Zuffenhausen 928s. I've also had the opportunity to see several of these years later. In all cases but one, the factory-installed seals are still dry. The one case was an RMS on a super-low mileage '87 (arguably) untouched since '87. Since I clean the crap out of the front of the block when I do a belt job I'm pretty certain of my post-install observations.

On the flip side, I've seen a lot of 928s with records showing seal replacement and with no exceptions, for that set of cars, every seal I've found leaking has been replaced once before.

I've also seen 928s with records showing seal replacement that aren't leaking.

For leaking seals on 928s with no records that have been touched ... well... who knows...

My observations would suggest that 'robotic WYAIT' seal replacement has a higher likelihood of resulting in a leaking seal than leaving non-leaking seals in place.

A logical - but not necessarily correct - conclusion is that some replacement seals suck and/or that some seal replacement technicians suck.

If one has the factory (or functionally identical) seal drivers, is careful, and follows all R&R best practices then the expectation would be non-leaking seals.

On the other hand, if one is cobbling-together seal drivers and hasn't done seal replacements before or doesn't have evidence that their past seal replacements aren't leaking, then expectations probably need to be lowered.

Some folks on this forum fall into the first category. Many fall into the second.

I'm not sure where the OP is in this taxonomy. Thus the note of caution.

As far as the seals themselves are concerned, I've lately become obsessive about all of the replacement seals. Anything that doesn't look like a 100% duplicate of the factory seal gets tossed. So far the Elring seals are the closest to OE.

I've been using the Elring front wheel bearing seals for years now since they are the only double-lip seal available. The OE seals were double-lip. If you order 'Porsche' seals, now, you get a single-lip seal. Will a single-lip front wheel bearing seal leak? I don't know. Will the double-lip seals leak? No.

worf928

Clarification: The above pertains specifically - and only - to front-main, rear-main, and cam lip seals along with the o-ring on the oil pump body.

Mrmerlin

FWIW if you use DC111 on the oil pump O ring the chances of it leaking in future decrease as the sealant preserves the rubber keeping it soft ,
oil will harden the rubber after long term heat cycles