How to verify a Porsche IMS bearing replacement from the paperwork

The gap is worth closing, because "IMS done" written in biro on a service sheet is not evidence of anything, and a great many cars are sold on exactly that. What follows is what a genuine record contains, and the specific absences that should slow you down.

First, work out whether the car even has a bearing you can replace

The intermediate shaft bearing is a feature of the M96 and M97 engines. That covers the 996, the early 997, and the contemporary Boxster and Cayman. Three cases matter and they are not the same:

• Early cars, broadly the first years of the 996, generally use a dual row bearing. It is the more robust of the arrangements, and plenty of owners choose to leave it alone.
• Later 996 and 997.1 cars generally use a single row bearing. This is the one the aftermarket exists to replace, and it can be changed with the engine in the car.
• The last of the M97 cars, roughly the 2006 to 2008 window, use a larger bearing that cannot be replaced without splitting the engine. If a seller of one of these tells you the IMS was done as a routine job, that claim needs a very detailed invoice behind it, because the work is a great deal more involved than a bearing swap.

Cars with the direct injection engines that followed have no intermediate shaft bearing at all. A seller offering IMS paperwork for one of those has misunderstood their own car, which tells you something about the rest of the folder.

The point is that the claim has to be plausible for the specific car before the paperwork is worth reading. Establish which engine is in front of you first.

What a real invoice contains

The job is not a line item. Reaching the bearing means the transmission comes off, so a genuine invoice reads like a much bigger piece of work than the phrase "IMS bearing" suggests. Look for:

• The kit named as a product, not as a concept. A real parts line names what was fitted, from a supplier that makes such a thing, with a part number beside it. "IMS bearing" alone is a description of an intention.
• The clutch, and usually the rear main seal. The gearbox is already off. Almost nobody puts it back with the original clutch and seal, and an invoice that shows the bearing changed but no attention paid to either is describing either an unusual decision or a job that did not happen the way it is written.
• Labour that matches the work. This is many hours. An invoice showing an hour of labour is not describing this job.
• The odometer reading and the date. Without a mileage, the record cannot be placed in the car's life, and a bearing changed at an unknown point is close to worthless as a fact.
• A note on what came out. Good shops record the condition of the old bearing and often what the oil filter contained when cut open. That sentence is the difference between a receipt and an account.

Remove transmission, clutch, flywheel. Supply and fit [named retrofit kit, part no.]. Supply and fit clutch kit and rear main seal. Cut and inspect old filter, no ferrous debris. Odometer 84,120 km.

That is a record. It names the part, accounts for the surrounding work, and fixes the event to a point in the car's life.

The serial number nobody looks for

The better known retrofit kits ship with a serial numbered decal that the installer is meant to fix to the car, commonly in a door jamb or under the rear deck lid. The manufacturers keep a lookup that lets you check a serial, and in some cases a VIN, against their own records of what was sold and registered.

This is the strongest form of proof available on this particular job, and it is independent of the seller. If the decal is there, note the number and check it. If the seller says the work was done with a kit of that type and there is no decal anywhere on the car, that is worth a question. Not an accusation, because decals do get lost when panels are painted, but a question.

The tells that the record is thin

None of these prove anything on their own. Together they are a pattern:

• "IMS done" on a service sheet with no parts line and no invoice behind it.
• A bearing change with no clutch, no seal, and a labour figure that could not cover removing the gearbox.
• No odometer reading anywhere on the document.
• A document that names no shop, or names a shop that no longer exists and left no other trace in the folder.
• The work appearing only in the seller's own summary of the car's history, with no receipt underneath it. A summary written by the person selling you the car is a claim, not a record.

Why this generalises

The IMS question is the clearest example of something true of every car with a story: the folder contains two very different kinds of paper. There are documents produced by a third party at the time the work happened, and there are statements written later by someone with an interest in the sale. Both look similar on a table. Only one is evidence.

The same reading applies to a stamped German service book, and to the rod bearing history on an E46 M3, which has the same shape: one job that decides the value of the car, and an invoice that either accounts for it or does not.