Details Behind the Cold Start Fix

Since our story last week on the 2007-2009 Cooper S cold start issues we’ve had loads of emails asking some basic questions on the issue and the fix. So in an effort to clear up some of the confusion, here’s the inside info into getting this fix applied to your 2007+ MCS.

First up the PuMA reference we used earlier is simply BMW speak or a file created to track the problems on one specific vehicle. The actual reference number for the timing chain rattle problem is SIM-11-02-07. This file provides information to the service advisor and repair tech for diagnosis, parts required, repair procedures, and warranty reporting requirements.

The first section of the SIM-11-02-07 document deals with verifying the timing chain rattle is occurring and not due to other potential issues.

Once confirmed, the old tensioner piston is removed and the new one inserted with the locking nut backed fully off. The piston is then torqued to a specfic value, the locking nut finger-tightened to the block, then the entire assembly removed. If the measured distance from the tip of the piston to the lock nut is 68 mm or greater, the timing chain, guides, rails, crankshaft sprocket, and camshaft bolts are replaced.

SIM 11-02-07 specifically states to not replace the camshaft sprocket or the Vanos unit unless other problems are observed. BMW engineering personnel must approve each case of the complete part replacement, but based on our sources, so far approval has been granted in all cases.

Based on comments we’ve received from readers, dealerships and service advisors are now becoming more helpful with this process. However as most MF readers know, it’s always helpful to understand what the process is and what is actually being fixed. So with that in mind it might be helpful to have this information in hand when talking with your service advisor.

Have you had your cold start issue fixed? Not all cars have the issue but enough have that we’re guessing there are quite a few stories out there of MF readers going through this process. If so let us know how it’s gone and what advice you have for other owners.

Thanks to MF reader Dick Mason for contributing to this article.