99 need advice on service - 100K miles

I have a 1999 (98 build) with just under 100K miles, original IMS. I bought it just over a year ago and have done as much of the simple maintenance as i can myself, took care of a number of differed maintenance issues, still one or two small things to go. However, i'm going to plan to have the IMS done this year, planning to reach out to a couple of local indy shops and get quotes, what i'd like to know is what should i be having done at the same time. My thinking based on cruising this forum is: Clutch (and flywheel) IMS RMS AOS Anything else that would be worth replacing on a 25year old car while the shop is in their? I'll ask the shops for their recommendations as well but I'd like to have an idea of what would make sense and what is the shop padding their numbers. I'm pretty handy so the simple stuff i like to do myself. Can anyone give me some ballpark numbers on what a reasonable price should be for this kind of work? My clutch is not slipping so I don't have an immediate need to replace it, it's more the piece of mind of having the IMS behind me that's driving this, and while I'm having someone tear into it, taking care of all the other items that would be easier to access at the same time. I'm in Raleigh NC area, I'm planning to reach out to Import Motor Werks in Cary and Hyperformance garage in Apex. If anyone has an opinion on either or other options I'd love to hear them. I had Import Motor Werks do my PPI, and i've had Hyperfomrance garage program a new key and do some small work for me. Neither have done any real service work on my car.

If it wasnt recentky done, makes sense to change the water pump, ignition coils, spark plugs, fuel injectors and maf. For the aos, go with the uaos. Depending in if you had the sump dropped or not during your ppi, it may also make sense to drop it, see what's in it, see what's in the oil filter and scope the bores from the bottom up. I have a 3.6 so the guys with the 3.4s can tell you what else to do.

If the IMSB (intermediate shaft bearing) is the driving force, get and install the IMS Solution from LN Engineering. At their website they have a list of certified installers. Replace the clutch, dual mass flywheel, pressure plate and get the updated throw out bearing and clutch arm. Also correct on a new RMS and AOS while in there. Keep in mind that you have an early build (98) so you have a dual row IMSB, most robust and least problematic, so there is no rush and you should shop around prices. Might consider having the cam deviations checked prior to any work, i.e., dropping the motor and transmission is a major job. Might also consider new water pump, new thermostat, new serpentine belt and pulleys. At 100K the motor mounts might also need replacing. Easy to do when the motor is out. And, since the motor is out, purchase a new OE Porsche coolant expansion tank and replace. There is more someone else might think of. Upgraded chain tensioners, upgraded oil pressure piston...oh the list can get long. I would figure about $3,000+ in parts and $4,000 labor. Good luck...

The 98-99 MY builds have the beefier dual-row IMSB from the factory. This is not a gaurantee the bearing won't fail, but there are things you can do to monitor the conditon instead of jumping in. Filter inspection, oil analysis & cam deviation numbers are a good place to start. These can also give you an idea of your timing chain guides and if they require replacement. If you clutch is working fine and your RMS isn't leaking, I would be inclined to follow a monitoring pattern and wait for a reason to go down that road. Regarding the AOS, this can also be checked and monitored by regularly measuring crankcase vacuum. If you don't have any history of replacement and want to be proactive, the AOS can be changed without dropping the engine/transmission.

Ok, lots of good advice. I've done the sparks, spark tubes and coil packs, done the motor mounts and had the gear box oil and motor oil analyzed when I changed it, also took apart the filter and inspected, no signs of metal or any foreign objects and oil results where good (but not a lot of miles were on the oil so ???, I'm guessing a lot of miles were on the gear box oil). I also flushed the brake fluid, it was in bad shape even though the brakes were recently replaced (but not the rotors, typical resell job) rotors are in decent shape though. I did replace the valve and the cap on the coolant expansion tank, i didn't replace the entire tank... probably should have when i did the motor mounts. (The problem with experience is you have it after you need it). I believe the water pump was recently replaced (my neighbor owned the car before me for about 2 years and he put 1500 miles on it, he was told the water pump was replaced before he bought it, appearance wise this seems to be the case, but i have no records to prove it. I've got a serpentine belt and pulley kit in my garage waiting to go on, I've been thinking about doing the water pump just to be sure at the same time. Engine does not leak, clutch seems to be fine, I don't and likely won't be tracking the car, so it gets treated pretty well, get it good and warm at least a few times every month, more so when the weather is nice, but i still treat it like a 25yr old car.

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Looks like alot has been done which is good news. Double check on the water pump just in case. If one of the plastic fins breaks, it can get lodged where you dont want it too causing heat and cracking. 5-7 year replacement schedule for a relatively cheap part makes sense. Fresh fuel injectors if they haven't been replaced makes sense. Poorly functioning injectors can lead to excessive fuel in the cylinders and bore scoring due to the oil being diluted.

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Your definitely on the right path here with maintenence, if you don't have any history on the water pump then it should probably be replaced regardless of miles. Coolant reservior tanks typically start weeping so it's an easy one to keep an eye on. I use a remote mirror to look around/behind the tank to check for signs of cracks or weeping coolant. Since you have to unbolt/remove the motor mounts again anyway to do the water pump you might want to add the coolant tank to the list. The next step I would take is cam deviation numbers and fuel trims, that can give you a good idea of what you might need to address in the near future.

if the engine is out, do all the sensors and rebuild the starter.. Or at least change the Oil. level sensor, and the starter You could also while its all apart get the alternator hand rebuilt at a good shop. UAOS.. is easiest while engine out... Replace the oil filler tube.

I wouldn't talk yourself out of a clutch kit and replacement flywheel. IMHO, if you're going to spend the money to replace the IMS Bearing, RMS, AOS, etc... don't be foolish, replace the clutch kit and dual mass flywheel... the transmission is off anyway. Replace the crank position sensor among and check your camshaft deviations. It's probably time to change out the VarioCam wear pads.

No question. I would do every "while you are in there" item you can when the engine is out. Budget 10-15k and "get her done". Then enjoy for the next 20 years.

With a 23 year old car and 100K miles, I would definitely replace the cam wear pads and 4th & 5th chains. I am changing them on my 01 C2 with 59K miles and they definitely needed replacing. The cost for these parts is less than $100. I just bought them. If you replace the 8 camshaft sprocket bolts, be sure to get the correct ones. Early cars use 6 x 12 bolts but the PET shows them to be 6 x15. If you put in the longer bolts by mistake you can break the camshaft flange because the longer bolt will hit the cam caps. I am lucky I remembered reading that this happened to someone on this forum and checked mine. I got the longer bolts when I ordered them for my car. I called the Porsche dealer I ordered the bolts from, he checked and verified there were short and long bolts. You might want to upgrade to the 997 oil returns in the case to replace the swirl pots. I would also consider installing the UAOS with track drainback. That will provide a more robust AOS that is easily serviceable and also provide a new oil fill tube which should probably be replaced at this mileage if it has not recently been replaced. They do become brittle with age and crack causing a major vacuum leak. Good luck with the upcoming work. Mark

UAOS if you want to do it right.

If you rebuild the starter, change out the cable. Also, change out the oil filler tube.

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I went thru this the last three years. If your ims looks good not leaks, I would wait till is time to do the clutch. Awesome maintenance goes a long way. My car is sitting at 102k miles. 12k of those by me. Join PCA you�ll meet members at the cars and coffees etc. More than likely someone will have a durametric and you can run fuel trims, cam deviations. I been told by a few mechanics wait to change the ims until it�s time to change the clutch. Do run good fuel, I have access to ethanol free other than that I run shell v power 93. Run Techron thru the tank. Some people like seafoam. Run CRC GDI thru the intake. I change the oil every 6 months, I look at the filter. Heat is bad for these engines, low temp thermostat and water pump. I would suggest not to throw a lot of money at the car until you are certain you are going to keep the car. Find a shop that you are comfortable with and stick with them. definitely take the front bumper off and clean the radiators. I have done that at my mechanic on both the 99 and my 03 turbo.

100% agree with changing out the starter/alternator cable. As a way to save money, one cable runs from the alternator to the starter and another runs from the starter to the + jump start point and from there to the battery. The two cables (from alternator and from + jump point) are crimped together and not sealed from the elements. Over time it corrodes and the traditional equipment to test the battery and alternator doesn't detect it, so a lot of us (me included) have kept the battery and alternator makers in business with the wrong diagnosis.

Yeah this is exactly why I'm asking, I'd rather do it once and have it all done. But i also want to do as much of it as i can, in my humble garage (no lift). So if i can check off some of the ancillary items first, i will, hopefully keeping the costs down when i take it to the shop for the complicated stuff. There is a lot more i need to add to my list than i had originally planned.

Thanks for the insight, yeah I've been hoping to get to a cars and coffee or PCA meet up, there are a few not far from me, I have 3 young kids though and the days of the meet ups tend to be when my kids have sports... so I just haven't made it. I'll make it a priority before I get to deep into the maintenance list, I've been wanting to have a knowledgeable critical eye take a look at my car. I did take the front bumper off (replaced the horns) cleaned up the radiators so that was done recently.

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Is this the case for an early 99? I was thinking there was no positive charge point in my car as i have the manual release for both the trunk and the decklid. Regardless it's a good point to replace the cable at the same time thank you.

Yes. The jump starting point is housed inside a little black box, about the size of Walker Shortbread just to the right of the power steering fill. It has a little + sign on it. When you open it, hinge on the right, you expose a fitting you attach the plus side of your jumper cable. If you have the Bentley service manual, it is page 03-03. My '02 comes out of winter storage this Friday and I can't wait. Weather has been awesome.