I took delivery of my 2007 MCS on April 28. The car has been excellent, with expected great handling, acceleration, and braking. After about 2400 miles, I am getting 35 mpg average, and thoroughly pleased. One question, though:

In late May and now in June, sometimes on startup the engine will run rough and occasionally make rattling or maybe scraping sounds -- for up to one or two minutes. Then it smooths out, and runs fine. This usually occurs just after a change in the weather, such as a shift in humidity and temperature (I live in Iowa, with humid-continental climate). The other day it happened after I gave the car a thorough bathing and waxing.

Is the computer just adapting to new conditions as read by the engine sensors?

 

Its been reported elsewhere that the tensioner for the timing chain relys on oil pressure to build tension on the assembly. So when the car first starts its possible for the tension on the chain to be low, and for it to make a rough noise until oil pressure climbs and the mechanism does its job.

My MCS did this one morning in March when the temperature dipped into the low teens. If you are getting the sound in warm weather, and every time you start then I would have the service dept at the dealer look at it. Its possible the tensioning mechanism may have a problem.

That's all third hand knowledge I've read on messageboards. Or I may be completely in left field. Use your own common sense.

 

Aren't British cars great? So much character!

 

You're right! They are!

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edit:whoops - chakaluka is gone. another phony id bites the dust.

 

I've had it happen once under similar circumstances: Cold weather, car sat a few days while I was away during a race weeken. I just about poo'd when I heard it, but by the time I goit out to pop the bonnet it had gone away (<30 seconds).

I think it's normal... BUT I would recommend mentining it to the dealer during your next visit and insist the observation be documented. That way, if it turns out to be somthing bad down the road that leads to a failure, you have a paper trail documenting the noise very early on in the life of the car (and may qualify for a fix even if your out of warranty).

 

FWIW, my 2002 BMW 1150 w/boxer engine uses a similar cam chain tensioner design (x2). There was a widespread series of failures with the hydraulic tensioner assemblies in 2002 and dealers were stocking/replacing them like spark plugs.

The symptoms sound similar; could be the same type of condition, maybe not. I'm a new owner so I don't really know enough about these powerplants yet, just adding my 2 cents.

 

Thanks for the comments

Anyone else with experience/information?