but simply the way things are now.
My experience has been the diagnostics -- OBD2, comfort bus, or purely mechanical/automotive -- is just fine.
For the comfort bus, in the case of my Boxster and its door lock, the tech in less than an hour's time pinpointed the source of the problem and in another hour had the old door lock out and the new one in. A fraction of an hour was required to restore the car's comfort settgings. The lock is not rebuildable so the tech had to replace it. MAF. Not rebuildable (AFIAK). O2 sensors. Not rebuildable. But in all cases I've id'd the source of the problem and replaced the bad unit myself.
Wheel bearing. Not rebuildable.
AOS. Not rebuildable.
Now I did have the CV boots recently replaced and the CV bearings cleaned and greased. Believe it or not but the tech actually advised me to have these cleaned and regreased rather than replacing the half shafts with new ones. I have in the past preferred to replace driveshaft bearings with new ones but the $900+ cost (each) of new half shafts convinced me to listen to the tech and have him clean/regrease the old half shafts. He told me as long as the shafts are not allowed to run with failed CV boots his experience is the CV bearings are quite robust and a simple clean and regrease will have them as good as new again.
In the case of my Cayman S the tech id'd a bad radio and the radio was replaced. Again the radio simply isn't a field servicable item.
Back to the Boxster: no need to pay the tech to diagnose the converter; I have done that. But the converter is not rebuildable so I'm faced with having to replace it when the time comes.
Further back I id'd the water pump and simply had the car towed to a dealer and the water pump replaced.
As for the Boxster and its recent troubles with the VarioCam solenoid and actuator the problem was id'd in short order. In fact I had a pretty good idea what was wrong simply from the error code I read shortly after the check engine light came on but facing a partial teardown of the engine at that cost level I wanted some professional input as to what was wrong. The tech confirmed the solenoid was bad but the solenoid and actuator are not rebuildable so replacement was the only option. The actuator housing appears to have been welded shut. I can't find a bolt anywhere in its housing.
When the fuel pump quit the tech loaned me his fuel pump bypass relay and I verified the pump was not working. The car was towed to the dealer and the tech simply verified the pump had voltage and since it did the diagnosis was the fuel pump was bad which is just good automotive diagnostics. As with most other items the fuel pump is not rebuildable. In fact I disassembled it as far as I could and found the pump housing proper is sealed and can't be separated without resorting to chucking the thing in a lathe and turning away part of the housing to disassemble its innards. But I don't see how one could reasonably rebuild this pump.
With the Turbo, the radiator fan motor (shaft snapped), the idler roller bearing, the shifter linkage, the clutch accumulator and slave cylinder all had to be replaced. None of these items are rebuildable. Either the assemblies/hardware is not field servicable or Porsche doesn't offer spare parts for instance for the shifter linkage. In the case of the shifter problem just a plastic ball socket broke and had this been available separately I believe there is no reason why the old one could not have been removed and the new one fitted and the shifter resurrected. But the car was under warranty and a straight up replacement of the shifter is Porsche's answer. I have not had the time or the need to research if the ball socket is available over the counter or off the shelf. I've driven for decades and hundreds of thousands of miles and never had a shifter problem ever so a once in a lifetime replacement of a shifter is not a big deal to me. Now if this thing was going out more often, and me faced with paying to have it replaced, I'd be researching a shifter rebuild solution.
Now, the transmission. Because the car was covered by a CPO warranty Porsche's policy is (at least in this case) remove the old transmission and install a new one, one which came from Germany I was told. (The USA warehouses were out of stock of Turbo transmissions.) The factory sent over a remanufactured transmission rather than allow the techs to replace the leaking seal in the original transmission. However, the techs told me that if the car had not been covered by a CPO warranty and had I wanted the leak fixed they could have removed the transmission and torn it down and replaced the leaking the seal. The Turbo 6-speed and the NA 6-speed transmissions share parts and the selector shaft seals are such parts.
As for engines and engine rebuilds most owners facing this either do not have a good candidate engine for rebuilding -- due to the reason the engine's sick in the first place oftentimes the engine's toast by the time the car makes it to the dealer or any place else for a professional diagnosis -- or elect to bypass a rebuild in favor of replacing the engine selecting one of the engine replacement options.
Were I faced with having to do something about my Boxster's engine, at the rebuild level, I do not think I'd have it rebuilt anyplace but use it for its core charge value and have the engine replaced.
Oh, not my car but I have been in various Porsche dealer and their service departments and seen engines and transmissions down and being repaired. For instance, not too many weeks ago, I came upon a 997 Turbo in a service bay on a lift with its engine out and one of its camshaft covers removed so the tech could replace a bad VarioCam actuator. However, as was the case with my Boxster, this VarioCam actuator while it did have bolts and the tech told me he has disassembled one before to see what he could see Porsche does not offer any parts to rebuild/repair the things.
Sincerely,
MarcW.