What’s the deal with 13 mm wide belts? - PeachParts Mercedes-Benz Forum

JHZR2 · #1 04-07-2019, 10:56 PM

It has been a long while since I’ve done any bell work on a W123. I’m doing belts right now on my 240D, and had bought some continental ones here at peachparts. When they arrived besides being disappointed that they are made in China, I noticed that they are all 13 mm wide.

By any chance has anyone purchased original equipment Mercedes belts for these cars recently and can they comment on the country of origin if bought as OE parts?

I pulled the belt off of my 240 D, and found that one of them actually is a 13 mm wide original equipment made in Germany belt with the Mercedes star on it. The other two were 12.5 mm wide and also were original equipment Mercedes Benz belts made in Germany.

Does anyone know why they went from 12.5 to 13 mm? Does it really matter? Given that the continental belts are made in China anyway would it be worthwhile to look for a 12.5 mm belt?

The 13.5 mm belt seem to fit just fine in my pulley and the air conditioning compressor though the compressor was skewed and so the bell has a little bit of shredding on the edges.

The belts do stretch a lot even with minimal use. I couldn’t fully tension the ac belt anymore even With low miles and limited use.

Squiggle Dog · #2 04-08-2019, 12:00 AM

In my experience, genuine Mercedes belts are 12.5mm, and aftermarket belts (including Continental without the star logo) are 13mm. It shouldn't make much difference. I had Chinese 13mm Continental belts and then bought genuine Mercedes, which were 12.5mm Continental belts with the star logo, and made in Germany, and better quality than "non-genuine Mercedes".

JHZR2 · #3 04-08-2019, 12:24 AM

So, as you can see, Mercedes belts with the star may be both...

I don’t even see 12.5mm belts here at Pelican, for the OE offerings.

Squiggle Dog · #4 04-08-2019, 05:06 PM

Also, when I've purchased belts, I've found that the genuine Mercedes Continental ones were 9.5mm wide, while the same part number in aftermarket Continental were 10mm wide.

I purchased a genuine Mercedes belt for my compressor, and it ended up being 13mm wide instead of 12.5mm like the genuine ones usually are, but it was a German Optibelt brand (with the star logo).

In short, I wouldn't worry about .5mm in width. I think a lot of it has to do with belts for the aftermarket rounding them up to a whole number. If you want German made, you have to buy genuine Mercedes.