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The saga with my 1990 S4 has landed it in the hands of Howard at European Classics in Atlanta. No compression on Cylinder 8 meant an engine pull. Now, I need to decide what else to do while the engine is out.
I have already done the following recently (within last 15K miles)
- Delrin Bushings
- Shocks
- Motor mounts
- Oil Pan Gasket
- Full Intake refresh (which preceded #8 losing compression!)
- Full replacement of all rubber in engine compartment
What I think I want to have him do...
- Reitech Clamp (car is automatic)
- New AC Compressor
- TB/WP Replacement and maybe change over to some pristine used cam gears
- GB Oil Cooler lines
What else?
Lastly - what AC lines below are hard to replace while engine is in? May go with rebuild of AC lines...
i did them with the engine in via Greg Browns awesome tool and recommendation on a wrench...but..if its out....do them.
also, if i had the chance again, i would try and get a custom fitting/extension brazed on the hard line that has the charging port for the AC..... would make it infinitely easier to access.
If you are going to do the AC Compressor then do the long line that runs from the expansion valve to the dryer too (#21 above.) I didn't do it when my engine was out then promptly had it start leaking after the engine was already back in and had to use Greg Brown's kit to braze on a new fitting since the rest of the line was inaccessible at that point. The kit worked great but was super nervewracking since it involves a MAPP torch in the engine bay. Rebuilding #29 and #31 is also pretty standard but make sure the shop pays very close attention to the clocking of the fittings or you will have a very hard time getting it back together (ask me how I know.)
+1 on brake and AC components. Other ideas: You can replace the cam seals, front crank seal, rear crank seal, and oil pump seals with the engine in... but they're going to be easy with the engine out. Maybe also consider doing (or at least inspecting) torque tube bearings, torque tube vibration absorber, and transmission mounts. Also the heater control valve, heater hose lines that go to the top firewall and any original fuel lines (though it sounds like you may have replaced these already). Inspect and consider replacing your fuel injection harness, front of engine harness, and main under-hood harness. You should also do an intense engine bay cleaning and inspect/replace any dried, cracked or missing clamps, hold-downs or (Porsche special) zip ties. Oh and consider having the various plated metal parts all removed and re-plated! And while I don't own an S4, is the CPS easier to replace with the engine out? Any other sensors?
EDIT: Also consider replacing the oil level sender and oil pressure sender.
If you are going to do the AC Compressor then do the long line that runs from the expansion valve to the dryer too (#21 above.) I didn't do it when my engine was out then promptly had it start leaking after the engine was already back in and had to use Greg Brown's kit to braze on a new fitting since the rest of the line was inaccessible at that point. The kit worked great but was super nervewracking since it involves a MAPP torch in the engine bay. Rebuilding #29 and #31 is also pretty standard but make sure the shop pays very close attention to the clocking of the fittings or you will have a very hard time getting it back together (ask me how I know.)
i did them with the engine in via Greg Browns awesome tool and recommendation on a wrench...but..if its out....do them.
also, if i had the chance again, i would try and get a custom fitting/extension brazed on the hard line that has the charging port for the AC..... would make it infinitely easier to access.
yer on a slippery slope!
Super Advice! I really like the extension idea for the charging port. I probably will get the shop to do the upper A-Arms, too. The slope is slippery
Change out the fuel cooler for one from a GTS, it has an AC fill port on it making it much easier to service than the one buried by the coolant hoses.
Replace all the rubber and gaskets on the engine as replacing a rear main seal is a PITA with the engine in in an auto car.
Definitely replace your AC compressor as recommended above. PS, have the bolts chamfered by a machinist so that it is easier to align the bolt holes and the the compressor.
This will turn a 1 hour job into a 2 minute one as you're no longer struggling to align the bores on the compressor with the holes in the mounts.
The only difficult line to do with the engine in is the long one you need to braze a new end on as mentioned above.
Also, replace all fuel and power steering lines (yes, even the cooler line in front of the condenser) if they are older than 10 years.
Another thing to think about is that if your cam gears are worn so are your oil pump and crank gears. Replace all 4 if they are worn or else they will transfer wear to the newer part and wear them out faster.
Speaking of the slippery slope... In addition to the above:
Engine wiring harness hard and brittle? Consider replacing it... Clean every grounding point.
Now is also the time to get at all those sensors as well: Hall, oil pressure, temp, and that pesky Crank Position Sensor that is super difficult to remove and properly route the wiring while in the car...
Enjoy! You should have a fresh 928 when you are finished!
Make sure to stop excavating the engine bay before it starts looking like this :
Just kidding of course, but my suggestion would be to take as many pics as you can and document all the steps taken!
I probably spend more time on writing down what I did than I actually work on the car.
I will also try to do all I can on the A/C, as it is out of the car and more accessible than it will ever be again.
Most important things are already mentioned. My 2 cents:
Some tie-wraps are brittle or broken, rubber hoses are dry and I found quite a bit of rust on various components (like the engine suspension).
Now is the time to have those parts replaced or powder coated.
Keep up the good work! And please show some pics when it is finished......
Brake booster and Master cylinder.
Easy peasy with engine out. Murder with it in.
-Jason
^^^ I wish I'd had done that when my engine was out. My brake booster is still fine, but the MC is on the way out. Would've been good to replace both and be done with it for another 30 years.
Oh and as mentioned above - don't even consider putting the old harness back in. Those things are baked and crumbling. Get one of Sean's replacements. I was really glad I did.
12-02-2019, 04:05 PM
What to replace while engine is out?
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