jaystudios

So I'm new to the community, have been researching here, and now close to pulling the trigger on an '02 C2.

I've pulled the maintenance records from the dealer, where even tires were replaced/serviced by the owner. While I had the service advisor on the phone, I asked more pointed questions of the data dump that he sent me.

The RMS was replaced in '06-- what is the typical service life of these? The PPI will of course reveal its integrity now, but I wanted to see if there was a rule of thumb (other than if it ain't broke don't fix it).

So here's the peculiar part: in the same RMS service above, the dealer replaced the IMS Flange (according to the service notes), but not the IMS bearing itself. Does that strike you all as a bit odd? Or was the IMS bearing issue not yet known and infamous in '06? Was the design of the flange in the '02 MY flawed somehow? Why would the dealer skip the bearing-- the labor is done and the part inexpensive. I can only assume the bearing was pulled and determined to be sound enough to reinstall the existing one.

Thanks for your advice, and I hope to be a 996 owner soon.

silotwo

Hello and welcome. The RMS was notorious for leaking and Porsche had more than a few updated designs so yes, it's replacement in 06 would be typical. The IMSB failure was not so well known, but the IMS seal was known to weap or leak and again there were a redesigns of the seal and flange so in 06 replacing the bearing at the same time would not be typical at all.

Doubtful that the bearing was pulled and checked when the flange was replaced. And, other than a visual external check for leaks, a PPI will not guarantee that the RMS is not weaping or leaking. I have an 04 C2 and the RMS was replaced by the dealer before I purchased the car in 2007. In Sept of 2012 I had the clutch and IMSB replaced and the RMS was still bone dry - 5 years and over 50k miles of service with no issue.

Dharn55

Porsche developed a revised flange to address leaks. It has better seals than the original flange. I have one in my car that I installed in 2009. At that time LN Engineering and Flat6 were still developing the techniques for removing the IMS bearings. They had a pretty good handle on the single row bearing removal, but not the dual row bearing that my car has. That is why I did not do the bearing upgrade back then. I did remove the outer seal on my bearing then.

There is no way dealers were replacing bearings back in 06. Dealers were late in adopting bearing replacement even after the removal techniques were developed.

Macster

Not odd based on my experience with my 02 Boxster. Back in 02 the engine exhibited the symptoms of an RMS leak.

The car was under warranty so in it went.

The SM told me that because the RMS and IMS were so close together that often times (earlier RMS repairs) when just the RMS was replaced the car was back with an RMS leak when the real problem was the IMS end plate.

So the SOP was to at the same time the RMS was replaced to replace the IMS flange or end plate.

The new one had an updated/improved 3-rib seal vs. the single o-ring seal of the old one. Additionally the 3 bolts were micro-sealed to prevent oil from seeping past the bolt threads and out from around the bolt head.

The only check that was made at the time the RMS/IMS end plate were replaced was to check the location of the crankshaft journal to ensure the crank was not out of position. In a few cases this was found to be the case and the engine was replaced. The RMS would not remain oil tight for long and often times the engine would self destruct before the RMS leaked enough to make a problem known.

This was way before the IMSB was even an issue.

In the case of the car you are asking about, even though in 06 IMSB failures were not unheard of, I can assure you the IMSB bearing was not thoroughly inspected and found ok.

I'm sure it was superficially inspected. Well, that may not be the best word, but I'm sure had there been obvious signs of bearing imminent bearing failure just the IMS end plate was replaced.

The bearing would not have been replaced in any event. The engine would have been replaced.

Dennis C

I had my IMS flange replaced when my RMS was replaced at ~74K miles. It hasn't leaked a drop since!

jaystudios

Wow, thanks for the great advice and historical perspective everyone. Gives me a bit of confidence that they did all that was known at that time.

The owner has put on about 17k miles since then, and disclosed that the RMS showed a drop of leakage while storing over the winter. I'd assume that to be normal in a car that is 11 years old, and quite good-- I've had a Range Rover classic and Triumph, so a leak like that would have been suspect in those cars.

Now at the risk of being a total noob... how is the RMS/IMS kept lubed? As part of the normal engine oil system? Or some other way like a transmission or power steering box? Sorry, I don't have the manuals yet to read more on the subject.

Thanks in advance!

Macster

The RMS is lubed by oil splash/oil vapor that is present in the crankcase. The RMS doesn't need much lubrication and in fact doesn't want to be subject to much oil because the more oil it has to keep in the engine.

At one end the IMS (intermediate shaft) is lubed via high pressure oil from the oil pump. At the other end the IMS is supported by a sealed ball/roller bearing. This bearing is nominally lubed by the entrapped grease/bearing lube sealed in the bearing.

There is a question as to whether the bearing seal can survive intact over the miles/years. Almost certainly if the seal fails whatever oil gets to the baring will wash out the grease. The bearing is kind of off the beaten path when it comes to oiling, in that there is no oil feed to this area. Since the bearing is sealed there is no need.

From them on the thinking is the bearing is lubed by any oil that manages to make its way to the bearing.

The seal on the IMS flange/end plate doesn't rotate nor does anything rotate around it so it doesn't need lubrication. The fact it is subjected to considerable oil keeps it wet and pliable and in no danger from drying out and thus shrinking.

Dennis C

You've actually hit on the flaw with the IMSB design. The IMSB is a sealed bearing, and it's not designed to be lubricated by an external source. After it has been used for a while, it tends to lose the seal, allowing the original lubricant to leak out and engine oil seep into the bearing.

You often hear that cars that are driven frequently are less prone to IMSB failure than low-mileage cars. The theory behind this is that cars that are driven frequently keep the IMSB sufficiently lubricated that it will continue to function effectively. If a car isn't driven frequently, the engine oil that has penetrated the seal will seep out, leaving a "dry" bearing. This can be especially problematic at start up, causing rapid failure of the bearing. This theory makes sense, but make no mistake - cars that are driven regularly can still suffer IMSB failure.

Your best bet is to treat the IMSB as a wear item and replace it every so often. Upgrading to a ceramic bearing like the one from LN Engineering is also a good idea.

This isn't meant to scare you away - just to inform you. I'm still on my original IMSB at ~123K miles. I'm planning to change it to a ceramic bearing on my next clutch change, which won't be long.

Macster

My 02 Boxster's RMS/IMS flange was done at 25K miles back in mid-02. At 266K miles the RMS and IMS flange seal are still dry.

Dennis C

Nice!

jaystudios

@macster, that's some amazing mileage on your boxster or any car for that matter. Well done.

Thanks to the folks on this thread. Great stuff to know about how it all works. Per the PPI, the current RMS is showing a long slow leak, so a replacement is in order.
They cleaned it up down there, and ran it on the lift so they could watch it, and it stayed dry. I confirmed with the tech that the newer RMS is improved and more substantial.
There are some other nitpicky things, but the car has been taken care of. Thanks again, and I'll post pictures if I make it so.

WeakestLink

Reviving an old thread to get forum expertise.

I recently made an impulse purchase of a low mileage 2003 C2 coupe from a BMW dealer. Before I purchased, the BMW dealer confirmed with the Porsche dealer that the IMS retrofit had been completed in 2015. And I called the Porsche dealer myself and confirmed the same. Then I bought the car.

A week later, I stop by the Porsche dealer to get a copy of the service order for the IMS/RMS for my records. Upon review, I only see that the IMS flange was replaced...there is no mention of the IMS bearing being replaced. Additionally, the cost of parts on the invoice is only $263 with labor being $1485. I know the LNE solution costs over $650 so the low cost of the parts raises additional concerns.

If the Porsche dealer only replaced the IMS flange and did not replace the IMS bearing, does that reduce the risk of IMS failure? Or is the likelihood for failure the same since the potentially faulty IMS bearing was not replaced?

Thanks for your help.

billh1963

Replacing the flange alone will not save you from a potential IMSB failure.

The bearing has to be changed.

billh1963

Picture

WeakestLink

Thanks for the response. That's what I thought but I was hoping to be surprised with good news. That's life.