Is there truly no way to tell that it’s time to replace the IMSB?

[Liamray]

I have owned a 2001 2.7 Tiptronic Boxster for 3yrs now, and I had a major service carried out on it, the mechanic found ‘material’ in the filter, a lot of material. The mechanic thought it was the IMSB, and the material looked like alloy chips, but being a retired Aircraft Maintenance Engineer I did my own investigation. To cut a long story short, I removed the IMSB and it was a factory fitted dual row bearing, and it was in ‘as new’ condition, even the plastic seals looked new. Turns out the problem with my engine was not the IMSB, but another little discussed problem that affects the Boxster engine, my ‘Cam Chain Tensioners & Variocam Tensioners’ were shot. This in turn means that the cam timing is erratic at best, and dangerous at worst, when the Cam Chain Tensioners go it leaves the chains to basically ‘flap’ about untensioned, this in turn can put stress on the IMSB. Porsche should have made the Tensioners a regular service item, but they didn’t, my car with 147,000km on the clock, had three out of the five Tensioners fail. If you’ve heard of the ‘NORMAL’ chain rattle at start up or when the engine is cold, this is a lie! If the Tensioners are operational then there is no rattle. So the IMSB is not the only thing responsible for engine failures.

[Starter986]

Originally Posted by Liamray

I have owned a 2001 2.7 Tiptronic Boxster for 3yrs now, and I had a major service carried out on it, the mechanic found ‘material’ in the filter, a lot of material. The mechanic thought it was the IMSB, and the material looked like alloy chips, but being a retired Aircraft Maintenance Engineer I did my own investigation. To cut a long story short, I removed the IMSB and it was a factory fitted dual row bearing, and it was in ‘as new’ condition, even the plastic seals looked new. Turns out the problem with my engine was not the IMSB, but another little discussed problem that affects the Boxster engine, my ‘Cam Chain Tensioners & Variocam Tensioners’ were shot. This in turn means that the cam timing is erratic at best, and dangerous at worst, when the Cam Chain Tensioners go it leaves the chains to basically ‘flap’ about untensioned, this in turn can put stress on the IMSB. Porsche should have made the Tensioners a regular service item, but they didn’t, my car with 147,000km on the clock, had three out of the five Tensioners fail. If you’ve heard of the ‘NORMAL’ chain rattle at start up or when the engine is cold, this is a lie! If the Tensioners are operational then there is no rattle. So the IMSB is not the only thing responsible for engine failures.

I've got that startup rattle. Arghhhhh. My reading reveals that I would be ill-equipped to replace the three tensioners.

Think I'll get a Mother Mary to stick on my dash and, no, I'm not talking UFO.

[jsceash]

If you had a Durametrics and monitor the Cam Shaft deviation that may give you a perspective on a couple item. Chain rail condition, tensioner condition and IMS. That with oil filter inspections. are a good starting point.