rennbob

Man, I feel your pain. But you can at least replace clutch/flywheel/RMS/flange seal if needed?

Now that my AOS / IMS / clutch replacement is done, my 99 996 with 103k miles seems to run a little warmer than I remember. So I used to the purge valve to to bleed any air introduced by opening the AOS coolant lines. I cleaned the rads and AC condensers, yes there was a lot of gunk after 15 years! :D Neither helped much. From cold start, 65-70F ambient, it takes 9 miles to get to ~85C. (4 miles of 40MPH non-stop, then 5 mi of 70MPH) By comparison my Lotus Elise will be at 85C within the first 4 miles. The car will stay at 86-88C if 60+MPH is maintained, but monotonically increases into the 90s then 100+C if there is any stop and go. It never easily seems to cool back down, even in long bursts of 40MPH. Once on a clear highway at 70MPH it takes ~8(!) miles to get back down to 87C. Again for comparison, the Lotus will drop from ~97C to 85C in just a few minutes once it has clean airflow. When idling, the 996 fans come on at 100C and takes 4-5 minutes to fan shutoff at 97C. The slow warmup and cool down--"high thermal mass"--seem longish to me. The water pump was replaced at 87k miles, but the t-stat is original. Perhaps the thermostat is stuck partially open? I haven't really pushed the high-temp stop-and-go testing yet. BTW, all temps are measured at OBDII, and I'm not interested in the 160F aftermarket t-stat. Thanks.

To answer my own question... follow the manual at 48 lb ft for all. This project is all done and she seems to be running well. [A little paranoid about the coolant temp, but that can be the subject of a new post]. Thanks everyone for all the help! :thumbup:

I have the same issue on my 1999 C2. I can retrain it, and then it works fine (one touch, etc) for about 5 minutes, and then "forgets". Other posts claim replacing the motor fixes the problem, but it's an expensive fix for something that still sorta works. Some engineering thoughts: My sunroof moves fine, maybe a little slowly, but not to the point of it sensing overcurrent and reversing the motor. Since it "forgets", I thought there might be a simple power supply problem to the microprocessor inside. The motor is a Siemens part, and the electronics inside look straightforward: a Motorola microcontroller, a Siemens chip that might be used to sense a magnetic encoder on the motor shaft, relay, and a few jellybean SMT parts for the switch inputs, etc. I don't really see any parts that would impact the power supply; there is one electrolytic 47uF cap but it looked fine and tested at ~47uF with my DMM. If I had had the time I would have swapped that out with a new one. There's a few small diodes and one larger diode, they tested ok in-circuit too. I didn't see any external memory (EEPROM, etc) so I assume the training parameters are just kept in SRAM in the microcontroller while it's powered. Or perhaps the microcontroller has some internal non-volatile memory for the parameters, and that no longer works? I was short on time so I just tried reflowing the solder around some of the components, but didn't want to go too crazy; a half working sunroof is better than none. I cleaned the connector contacts and reinstalled everything and it works just as before: relearns and operates fine, but forgets in about 5 minutes. :-( Perhaps the current draw from the motor drops the voltage down low enough to trigger the controller's power-on reset? But that still doesn't explain why it works fine for the first 5 minutes... Have any other electronics-savvy RennTechers looked into this?

Got pulled away from the project for a little bit. Now almost everything is back together. Can anyone confirm the latest torque specs for the 6 M10 nuts that hold the two piece transmission carrier (at the front of the transmission, 4+2 vertical studs into the body) and then the two long bolts that go crosswise-through the transmission carrier and transmission? My copy of the WSM says 48 lb ft for all, but there's a post from Loren that said the through bolts are 33 lb ft?

Here's a pic of my bolts still in the bag. I don't see any [colored] coating at all. I received these bolts only recently; I had been expecting micro-encapsulated bolts, and to install dry at 19 lbft + 120 deg. If there is no coating, then adding threadlocker would seem like a good idea. OTOH, the threadlocker may act as lubricant and render the base torque measurement inaccurate (if Porsche truly meant these to be installed dry). I will have to call the dealers tomorrow and figure out what's going on. If the answer is to add threadlocker, I assume I should use blue (med), not red? For fun here are the flywheel and PP bolts that came out of the car. Looks like a green coating on the flywheel bolts, nothing on PP.

I don't see any coating on the new flywheel and PP bolts I think the parts guy told me he hasn't seen micro-encapsulation of the flywheel bolts in years, and they usually go in dry. I wish Porsche had a definitive recommendation for this. I couldn't find anything in my copy of the workshop manuals, but mine is not necessarily up to date.

Cool. Then in it will go tomorrow AM. Hoping to get a lot of re-assembly done tomorrow. Just to confirm, no threadlocker on flywheel, pressure plate, transmission case, CV bolts, right? There is some "green" on many of the bolts but that might just be corrosion...

So just skip the bearing compound? Do you ever use it for the IMS at your shop? Reading the LN instructions and a post by Raby, they say "consider" using bearing compound if there are signs of movement / ovality in the s_haft. It likely moved a little up/down as there are a few smaller marks 180 degrees from the ones shown. But then it's gone 100k miles and doesn't look like it has spun in the sha_ft. I'd prefer not to use compound as it could make installation and removal more difficult. The bearing is full of oil, no grease. The inside of the IMS looks OK, no marks. In the meantime, look what fell out: :)

Thanks for all the help so far guys. Bearing is out without issue. I notice a few marks on the outer race (see pics)... Do I really need any bearing retaining compound for the new one? Or do they all pretty much look like this? The old bearing looks and feels like new otherwise. I want to to finish this up!

Took 5 min to pull the FW with the gun. Behind it found a surprise, the oil leak looks to be from the IMS flange, not the RMS. RMS is old style (it was replaced 2X under warranty). I had already ordered a new RMS, and have access to the Porsche install tool. Should I leave well enough alone or replace the RMS?! While waiting for parts I've started scoping the AOS, can really only get one arm in the space at a time. Having second thoughts, I don't wan't to get stuck halfway with those !@##$ hose clamps. The AOS is still functional, although still leaking a bit from the bellows. I suppose I would replace the coolant hose clamps with worm type. Anyone know a local Bay Area CA source for Loctite 574 or Curil-T? 100k mile flywheel passed movement and return-to-center test with flying colors, but there's a lip and the worn face doesn't feel perfectly flat. Ordered a new one. And dead blow hammer already purchased and freezer is anxiously awaiting the bearing!

Cool. Thanks. I will post the status over the next week or two!

Now I'm confused: "Then remove the cam plugs on the cylinder head facing the flywheel". Facing the flywheel, the visible plugs are on the left, which is Bank 2, no? Don't I want Bank 1 cam plugs, near the alternator? I've already done a trial run with finding TDC (or TDC overlap) and locking it with a 5/16 pin. No problem. But I may have to rotate 360 several times to get the tool to lock?

Interesting thread. So this means that I need to find overlap TDC #1 for the IMS procedure on my 5-chain motor? The LN tool should only lock in this one way, correct? 1) Crank clockwise until overlap TDC #1 is seen - cyl #1 exhaust has just closed, cyl #1 intake is just about to open - cyl #6 exhaust open, cyl #5 intake open - bank 1 smaller circular cutouts are pointing away from the engine (or when looking at bank 1 and intake camshaft is above and exhaust camshaft is below, then smaller circular cutouts are on the left side, larger cutouts on the right side) 2) Lock bank 1

Thanks guys for the replies. Any other opinions on flywheel bolts? I think I might at least use the gun to get the bolts off, and then torque by hand when reinstalling. Regarding TDC this is the quote I was referring to on another forum (search for "not another ims thread"). It was good to re-read it. >> This is where experience from other engines isn't beneficial.. If you attend my engine rebuild school you'll learn that at TDC EVERY VALVE in the M96 is "off lobe". >> The engine was designed in this manner and all camshafts are relaxed at this point. Domiac I see what you're saying, but either way I'll pin my crank, lock my cams, pull my tensioners and hopefully the job will go well.

I didn't mean for this to be a contentious topic. I have now had a chance to read the LN instructions, hopefully locking the cams won't add to much time and I will follow the instructions exactly. A few follow-on questions: 1) I found posts from Jack Raby saying locking the crank at TDC OR TDC Overlap is OK--either position will unload the IMS as all cam lobes are off the valves. But maybe the cam lock tool will only go in properly when I am truly on TDC? 2) To confirm, the camshafts in only one bank [cyl 1-3, drivers side USA 996, lower tensioner on flywheel side, cam plugs on crank pulley side] needs to be locked? 3) Still need to remove my flywheel. Thoughts on using an impact gun? I am currently planning on fab'ing a lock tool and using my breaker bars. However, have recently bought an impact gun...

Forgive me I have several outstanding questions on my current IMS/AOS/clutch/FW DIY on my 99 996 C2... I've read seemingly every post on every forum regarding the IMS replacement, but I'm still uncertain if I can safely shortcut locking the camshafts if I ensure that the crank is locked at TDC and the two bottom tensioners are out. I've spoken to a few Bay Area Porsche mechanics who say they never lock the camshafts, but of course the full instructions from LNE says to lock. I will err on the side of caution (lock), but would like to skip the step if it's truly not required. My 99 should be a 5 chain motor, which I understand is even less likely to skip a tooth during the operation.... If I lock, can I just lock the exhaust CAM (or intake, whichever is directly connected to the IMS) since exhaust/intake have their own chain? Or does the LNE lock tool force me to lock both exhaust and intake? Or perhaps I could I just lock one bank's camshafts, and not the other bank? Thanks.

I'm in the middle of a clutch/IMS/RMS/AOS replacement on my '99 996 C2, 100k miles, original clutch. 1) The bottom of the slave cylinder rubber bellows is slightly wet with fluid mixed with dirt/clutch dust. Is this a case of "they all do that" (esp after 15 years) or is this truly a sign of impending failure? 2) I was planning on replacing the flywheel (esp since i can get one "cheaply" for ~$500). But the flywheel looks pretty good-- i don't see any bluing from overheat, it does has some spots scattered over it. and it centers itself pretty firmly, with < 15mm movement in either direction. Replace these or no? I'm trying to walk the fine line between doing everything "while I'm in there" vs throwing money away on an old car.