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Old 02-03-2013, 11:56 AM   #9
thom4782
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Join Date: Sep 2010
Location: Foster City CA
Posts: 1,099
The IMSB question gets a lot of discussion IMHO for two reasons. One, if it fails, the results are catastrophic and expensive. Two, it's very hard to know with certainty whether your IMSB is close to failure or not.

The only sure way to tell is to remove the IMSB itself and inspect it. Otherwise, the indicators are vague. Metal debris in the oil filter is one key indicator, but the metal can also come from other parts of the engine. The absence of metal isn't a guarantee the IMSB is OK. Cam shaft deviations at idle that aren't absolutely flat are another indication of a IMSB that is starting to wobble. Oil leaking between the engine and the transmission is a third indicator where the IMSB seal is failing. A ticking sound in that same area can indicate that the end of the IMSB stud has brOKen.

Your car seems to be exhibiting two symptoms: varying cam shaft deviations at idle and a possible IMSB leak. If this were my car and I planned to replace the IMSB in the next year, I wouldn't wait. While it may turn out the current IMSB was perfectly OK, I'd at least know I had a much better bearing in its place.

If you want to hedge your bet, consider adding an IMS Guardian. It might provide an early enough warning of an impending IMS failure to avoid the engine trashing itself.
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