umirza85

So I've decided to go ahead and purchase the 03 C4S I've been looking at over the last week after having a PPI done I do have a question about something that came up during the PPI though.

The PPI has come out almost perfectly aside from one question mark. The mechanic had said there was a small amount of oil where the gear box joins with something... (not sure his exact words) but essentially he was saying its either the IMS (seal??)/RMS and you can't really know until you start taking stuff apart.

I do have a previous receipt from the car where in Feb 2013 the IMS and RMS seals were replaced. I have called the shop where that work was done and confirmed he replaced the seals only as he noticed the leaking - and until now it looks like everything has been great.

Now my question is I know that RMS's can need to be replaced multiple times, should I do a full IMS replacement also or just ask him to replace the seals again? How would I find out the cause of the leak/what would be the best going forward as a new long term owner of the car? I am assuming the labour to do IMS/RMS seals only is close enough to doing a full IMS replacement anyways and its only +£30 more for the part.

From the shop owners p.o.v he said if it was his car he would just do an IMS replacement/RMS for piece of mind. He has also suggested the using the latest porsche IMS (£30) vs those LN Engineering ones (£3-400!) as that should be sufficient and just making sure it gets the oil it needs. He also checked for bore scoring with a camera and said he saw a few marks but absolutely nothing to worry about with a car that has 70k miles which is great news - just make sure to warm up the car before any aggressive driving.

All in all this is the only 'problem' with the car, it is specced very well and the price is very fair. Im very excited to be picking it up next week and thanks to all the help from everyone along the way.

Macster

Before the IMSB became the bigger issue, the SOP when there was leak which was almost always attirbuted to the RMS was to replace the RMS along with the IMS end flange and its 3 bolts with a new/improved flange and micro-encapsulated bolts.

The word I got was often the leak was not the RMS but the older IMS end flange with its single o-ring or from its bolts.

Nowadays an owner is probably not going to be satisfied with just a new RMS and an upgraded IMS end flange and better sealed bolts, he's going to want to install some aftermarket IMSB upgrade. BTW, the 'B' stands for bearing and upgrading this is more expensive and more work that just replacing the IMS end flange and its bolts.b

Based on what you posted I question if the shop is confusing a new IMS end flange with an IMSB upgrade? A new end flange would I expect to sell for around £30 while a true IMSB replacement/upgrade would run in the £300 to £400 range.

AFAIK, Porsche does not sell the IMSB separately. It doesn't consider this a servicable item.

So you and the shop would have to decide on which aftermarket IMSB upgrade to install.

Warming up the engine fully before giving the engine the whip is just part of good engine doing what you can to to prolong/extend engine service life. You should follow reasonable oil/filter service intervals and run a good oil. (Any approved oil of a suitable viscosity for the temperatues in your area should suffice.)

BTW, I dare say the RMS installation is going to be a bit tricky. Part of a successfull RMS install job is to install the new seal where the old seal, or in the case of this car, the old seals, was (were) *NOT* installed.

This is to avoid placing the new seal where the old one resided. The old seal likely wore a shallow groove around the crank journal and if the new seal ends up at this same spot it will leak. If the tech removes the RMS and only finds one groove likely this explains why the replacement seal leaked. (My 02 Boxster received a replacement RMS (and IMS flange/bolts) back in 2002 and has remained leak free ever since so a replacement RMS (and IMS end flange/bolts) can remain oil tight for many years and many miles.)

umirza85

Well I guess in this case the IMS, and RMS seals were replaced. And I guess you are right that nowadays for piece of mind most people would be happier with a replacement/upgraded IMSB.

Guess I should call and confirm with him what exactly he meant by replacing the IMSB, and what part he usually uses. He did quote around £500 labour which sounds like the rate for replacing an IMSB.

Yes he did also mention to ignore what the manual says and make sure to do yearly oil changes.

I have read above about what you mean regarding making sure the new seal doesnt sit in the old groove. Im hoping maybe thats the only issue...but at the same time if hes going to that much trouble to replace the seals would it just make sense to also have him replace/upgrade the IMSB? or just stick with replacing the seals/end flange?

Thanks for the very detailed response.

Byprodriver

If you can find the date the RMS was last replaced that would be very helpful. Around 2005 is when the RMS that lasts was put into use. The only way to know for sure what is leaking is to remove the transmission & inspect each. Best thing to do is have a new LN IMSB installed by a well qualified mechanic.

umirza85

The RMS was last replaced in Feb 2013. I'm not too keen on doing the LN IMSB as it seems quite an expensive job labour wise. But if its something that is recommended over just doing the seals again then its not an issue.

Is the LN IMSB a lifetime solution, or just a xxxx miles/xx year thing? In that case wouldnt it be better to just replace the RMS seal and see if that remedies the problem as the IMS could be fine (considering 95% of the IMS's are lifetime parts)? Im sure this has been discussed to death - but spending that much to just change something that might not need to be changed seems crazy as the percentage of cars that were affected wasnt that high. And if this one is a 70k miles and not had a replacement yet seems like good luck (unless I just jinxed myself)

Either way the mechanic had suggested changing it and seems like the overall consensus for piece of mind is to change it.........What are the options besides the LN IMSB?

Castro Viejo

The LN single row pro IMS bearing replacement is considered a wear item, according to its manufacturer. I believe it's about 50,000 to 60,000 miles.

If your bearing was truly replaced in February 2013 -- presumably with the OE IMS bearing -- then you can take that chance at leaving it alone. Adding the LN, which is now $800, plus the additional labor, may be another $1,200 on top of what they're charging for the RMS change. If you believe the LN bearing is a big upgrade, and my personal belief and the general consensus says that it is, you should just have it done since the transmission has to be dropped anyway.

You should also consider replacing the clutch if there's significant wear, as that's also a commonly performed service during the IMS/RMS deal. That's another $600-$800 kit with no additional labor.

Another thing I've learned is that not every shop will have the necessary tool to install the LN single row pro bearing. That's a $200-$400 tool that many shops simply do not have. I went to one Indy Porsche tech in my area who did not have the tool to install the single row pro and simply insisted on just installing the older LN single row classic. I decided to go elsewhere.

All in all I would personally do the LN upgrade because this forum and others have impressed upon me of the danger of the OE IMS bearing. It's likely very exaggerated but, as a famous comedian once quipped, "It's already out there!"

Good luck!

street rod

Just to clarify, Porsche does not sell OE IMS bearings, so if he had it replaced it was with an aftermarket bearing.

Castro Viejo

In addition to the two I mentioned in my initial post, the Classic Single Row and the Single Row Pro, LN Engineering also has an IMS Solution, which is an oil fed bearing that they advertise as not ever needing to be replaced. I think this kit is about $1,200.

There are other IMS bearing replacements on the market, but the LN bearing is the one most discussed and seems to be the most popular.

Castro Viejo

Right. Apologies.

For whatever reason I read his post as originally the work was done at a dealer.

bal

PO of my car took it to a dealer s few years ago and, as a result of an engine rebuild, the IMSB was replaced with the "newest version" as seen in the M97 engines - I.e. It now cannot be replaced. This conclusion was arrived at based on service records and inspection by my Indy (approved by LN Engineering) when he was going to do the LN bearing installation earlier this month. Weird I know.

Spokayman

KIND OF. PORSCHE DOES NOT SELL THE SAME SIZE BEARING THAT THEY INSTALLED IN THE M96 ENGINE ORIGINALLY. INSTEAD THEY SELL THEIR NEWER LARGER BEARING AND SHAFT. IT'S STILL "OE" BUT NOT THE SAME PART.

YOUR BEARING ACTUALLY CAN BE REPLACED, BUT IT WOULD INVOLVE REMOVING THE ENGINE AND "SPLITTING THE CASE", WHICH IS QUITE A BIT MORE WORK ($$).

umirza85

Thanks this is some great info. I've expanded below on my thoughts based on this.

Also just to have the following is directly from LN Engineering's website:

I guess it really comes down to since I need to get the RMS changed as there is a leak I might as well get the IMS done (& clutch if needed) as Im already paying for the labour to drop the transmission.

As far as my options, please correct me if I'm wrong I can either go for the LN IMS PRO bearing, or go with the Porsche OE Larger bearing and shaft? And just keep doing the IMS every 75,000 miles with a clutch change?

Also I found a shop in the north of the UK which has the tool and will do a "New IMS Pro, RMS Change for 911 996 C4 Manual – £1110, or with new clutch – £1349" ($1600- $2030 USD respectively)

Thanks again for the replies all.

street rod

True but my point is you can not buy a Porsche IMS bearing by itself. If Porsche were to replace the whole shaft they use the newer bearing but almost no one does that because its way to expensive to install and does not make sense for preventative IMS replacement so no one does it. Factory rebuild is different than what we are discussing here.

Castro Viejo

Yes, it would seem that those are your options. Frankly as someone has already mentioned, replacing your current IMS bearing with the larger bearing and shaft from the m97 doesn't make much sense to me. There is still a known failure of the larger single row bearing of the m97 that, if you believe the Internet, appears to be practically eliminated with the LN bearing. Thus the reason why most of us will stick with the LN replacement (which I recently had an Indy do).

The price you've been quoted for the IMS, RMS, and clutch job isn't bad. If you have the means I'd say go for it for the peace of mind.

umirza85

Thanks, good to know about the price.

Its just confusing as you can imagine. I've been reading around and found another person in a similar situation on another board, and quite a few people have been suggesting just to wait for a major leak (not just some small leaking on the housing) or wait until the clutch needs to be done. Then do the seals/ims bearing (with either LN or an OE specced one).

Guess I can see the need to wait until something major needs to be done but just seems weird to me to wait while I know there is a minor leak.

And to reply to Castro's message earlier. I had called the shop and they said they had only done the IMS and RMS seals, so didnt replace the bearing. And I don't have any papers in the history that show when/if it was done. I am assuming that it wasnt as most major repair bills are present.