I have just joined the ranks of the "B-witched" with a used 2007 B200 from an independent dealer. For the most part, I am enjoying the car - nice ride, spacious yet small (aka Tardis), nicely finished (compared to similar sized cars at the same used price range), and reasonable fuel economy (apart from needing premium).
My problem is a pretty awful noise when the car starts up from "cold" (though it is hard to call it cold, given the weather we have been having). My B makes a chirping sound like a giant cricket, combined with a slow "chuffing" sound, like a baby train. Within three minutes, it fades to be indistinguishable from the background engine sound, and doesn't happen again while driving or after reasonable stops. If left long enough, you can hear it slightly on first starting.
Of course, I didn't notice it at the dealer as the car had been driven that day, and the mechanics report mentions no issues (other than the irrepressible brakes - yes it needed both front and rear rotors and pads replaced before it was put up for sale).
Now I am not mechanically minded, so I would appreciate some help from the wizards here as to the possible problem before I make the trek to the MB dealer for (expensive diagnosis). I would have thought perhaps a slipping serpentine belt, but it isn't really a squeal and why does the sound disappear?
Thanks for any light you can cast on this issue - and ideas whether I need to have this fixed pronto - the MB dealer is 3 1/4 hours away!
It's likely the supplementary air pump used to warm up the catalyst. They can make quite a racket. That noise may be "normal" so lie back and think of the environment
Serpentine belt...Mine chirped too and everyone said it looked fine and but I had it changed anyway and no more chirp or swooshing sounds. It didn’t look worn until compared with the new one and it was on tight (probably too tight since the new one is actually a bit bigger than the old one)
How many miles before you changed out the belt??? And good thing you stuck to your first instincts about changing out the belt.
You said the new belt was larger, I wonder if the problem was the fact the old belt did not stretch with use and the new belt takes this into consideration?
Bill
P.S. Probably wore out because of all the times your A/C is on and the extra drag. Hopefully most of the rest of the world will probably see a longer life.
Serpentine belt...Mine chirped too and everyone said it looked fine and but I had it changed anyway and no more chirp or swooshing sounds. It didn’t look worn until compared with the new one and it was on tight (probably too tight since the new one is actually a bit bigger than the old one)
Quote:
Originally Posted by Mike Tee
It's likely the supplementary air pump used to warm up the catalyst. They can make quite a racket. That noise may be "normal" so lie back and think of the environment
Thanks everyone for all the suggestions.
Bill - that was my first thought. We're new to the area, and it is pretty much a rural backwater still, with very few MBs around, so don't know a good independent mechanic yet. Would REALLY like to though, given MB prices!!
Nadine, did the chirping go away as the car warmed up? And how much did they charge for the belt replacement, if you don't mind me asking?
Mike - that could well explain it - especially the chuffing sound. Never having driven a B before, I don't know what's "normal"". It is not the sound itself that is a problem, rather what it might signify as an impending problem.
If it were idler pulleys etc, should that be covered under the warranty? BTW, forgot to say the car has 51K km (and is apparently 2 years overdue for its C service according to the "confuser"), and has CVT.
Have to say this forum is a great source to find out about the car - especially since the leasee failed to leave the manual !
It started to chirp somewhere around 25,000 miles (40,200 km) and would go away as soon as the engine temp would rise just the slightest. At about 33,000 miles (53,100 km) the chirp would last until the temp read 80. When the gauge moved to just the tiniest amount over 80 it would stop and start up again when the engine temp dropped below 80, which meant on cold nights I would hear the chirp even after driving for a while. By the time I had the belt changed I was also hearing a swoosh, swoosh, swoosh sound which was especially noticeable when driving slowly in areas where the sounds would bounce of buildings and the like.
The old belt was not stretched out but glazed and belt chirp at 25K does seem awfully soon so maybe that tiny bit longer belt will do the trick. The new belt is from Mercedes since there is no such thing as a 5PK1765 in the US aftermarket belt world…at least nothing that we could find in the past few months.
It took about 15 minutes to change the belt, even with the tight fit the mechanic said it was easy to change out. It was less than 30 USD for the installation and the belt was somewhere between 35-40 CAD. It has to be done from underneath the car so a lift is pretty much mandatory. While it’s up on the lift have them check for any loose heat shields, the one under the drivers seat had come loose in one spot which created a rather loud growl buzz sound that also would only happen when the engine was cold and only in a very narrow RPM range.
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Startup noise with B200 - help please! 
).
and the extra drag. Hopefully most of the rest of the world will probably see a longer life.
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