Looking to pick up a belt...see lots of listings for belts to fit engine number up to 12-031209 and listings for belts from engine number 12-067245 . Problem is that my engine number lies in between and don't see any belts for that range.
Any ideas on what's up with that?
Thanks in advance.

I ended up looking at the number on my old belt. ( 97 SL320 ) You will have to look closely as the numbers may have worn off.

Older engines had a belt driven emissions air pump, later cars had electrical pumps.

I think that there is also a high and low alternator mount.

Thanks for the info. Checked the belt but no numbers...must have worn off. Found place on ebay selling Contitech belts and sent them my VIN and engine number...they say their belt will fit my car so hopefully they are right. Bought it and will see how it goes.
Thanks again.

Another way to do this. Remove the belt, make a mark on the back ( smooth flat side ) then measure around the belt back to the mark. This is the outer circle measurement, have a look at the belt #, usually part of the number is the OC measurement in MM.

Also count the ribs as this will be part of the belt number.

Another way to do this. Remove the belt, make a mark on the back ( smooth flat side ) then measure around the belt back to the mark. This is the outer circle measurement, have a look at the belt #, usually part of the number is the OC measurement in MM.

Also count the ribs as this will be part of the belt number.

shaman15, if you call the Parts Department at your local MB dealer the rep will look up the proper length drive belt per the VIN for your vehicle. That will take the guess work out of the purchase.

__________________
Fred Hoelzle

I think the old belt has stretched and become a bit loose so not sure a measurement would work too well.

Nearest Benz dealer is couple hours away...just bought the car and have never dealt with a dealer...probably never will lol Will have to learn to work on it myself, which I am looking forward to. Have the belt coming so hopefully it will be the correct one.

Just to note, will be doing the "infamous" w140 timing chain cover seal replacement on the car this coming week as I have noticed a small oil leak from that area. First real mechanical job I will have done on this car. Hopefully all will go well.

Flat belts don't stretch much and, a belt won't stretch out to the next size.

Your might have a automatic tensioner on your car, these fail leaving a loose belt.

What sort of problem are you having that leads you to a stretched belt?

Tensioner seems pretty strong. Have a squeal..chirp...sound coming from the car. Took off the belt the other day...looks to be pretty worn and also gummy. Cleaned it off with Dawn dish detergent and rinsed and air dried it. When I put it back on the squealing was gone. But then got messing around with the engine to find the oil leak..sprayed a little gunk engine cleaner and might have gotten some on the belt. Anyway, found the oil leak (looks like timing cover seal) and put things back together. Squealing sound was back worse than ever. Figure the belt could use replacing so ordered one this afternoon. Will install when I change the timing chain cover seal. Have my 94 C280 to drive so won't have to drive the squealer till I get it done. lol
Thanks for your input.

There are a couple of things you can do to stop belt noise. Roughen up the flat ( not grooved ) pulleys with some 80 grit paper, a 45 degree swipe on a X pattern seems to work fine. What happens is the polished pulley lets the belt slide front to back causing the chirp. You can also roughen up the back of the belt a bit.

Belt dressing will only make things worse.

Yes, only had the car a couple of weeks and noticed that the previous owner had some belt dressing in the trunk so must have used it. I want to get an extra belt anyway. Will put this old one in the trunk with the spare. Always like to have an extra belt on hand. Only a 10 minute job to replace a belt if one breaks...better to ride home with a squeaky belt than to get towed home lol

Will try the new belt and see if it stops the squeak. If not, will address the pulleys as you suggest. Thanks for that.
Also will clean the pulleys with a toothbrush and some carb cleaner before I put the new belt on. There seems to be a bit of gunky belt dressing on the pulleys.

shaman15, you can buy the new drive belt anywhere, but call the Parts Department at any MB dealer to find out the proper length belt for your vehicle.

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Fred Hoelzle