Quote:
Originally Posted by Bobiam
Based on the vin you can determine if you have a single or double row IMS bearing. If a double row starts to fail, you may have a chance to shut it down immediately and save it with a replacement. If you hear your single row bearing failing, there's a good chance that you now own a sports car with an expensive aluminum boat anchor in back!!!!!!
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You are more than a little off base. The VIN numbers on these cars bear no relationship to the bearing styles, but the engine numbers can if they are original to the car. There is no actual "matching numbers" between VIN's and engine numbers in these cars.
From 1997-1999, the engines carried dual row bearings; 2000-2001 was a transitional period where the engine could have either a dual row or single row bearing. Unfortunately, the
only proven way to know which one is in the engine is to pull the gearbox, clutch, and flywheel and have a look at the bearing flange. From 2002 to 2004, these engines carried a single row bearing. Starting in 2005, Porsche mixed both single row and the third design non serviceable oversized bearing in the production, so again you are forced to take the car apart and look, only this time you are looking for a 22MM center bolt, which was only used on the over sized bearing.
From 2006 until the IMS was designed out with the start of the 9A1 engines, all carried the oversized bearings. Now the real problem child: After 2004, all factory reman engines used the oversized bearing, regardless of the year of the car they were installed into. So a 1999 car could have the non serviceable bearing in it if it had a new engine installed. Fortunately, all factory reman's carry the letters "AT" (for Austauschmotor, or reman engine), and their date of assembly can be decoded from the rest of the number sequence. If the engine is a 2004 or later, it is the oversized bearing, regardless of the model year of the car.
As for saving any style IMS engine once it starts to fail, that is a total crap shoot. Perhaps one or two out of a hundred engines with failing IMS bearings can be saved; so they are vastly more the exception rather than the rule. Once the IMS starts to go, it fills the entire engine with fine metal grit which chews up every moving part and is nearly impossible to get out of the engine without total disassembly, so standard practice for knowledgeable shops that handle IMS retrofit's is to pull the sump cover and look for traces of metal, and if it is found, decline to go further as that metal will ultimately chew up the new IMS as well as the rest of the engine, quickly leading to a failure. We have seen DIY attempts to save engine's already in failure mode to end up with the engine tearing itself to scrap in as little as 50 miles after an IMS retrofit and an abortive attempt to flush the metal out, so spending the time and money on doing a retrofit on an engine already with metal in it usually ends up being a total waste.