I took my 85 300TD to an indie for a total drive belt replacement, all continental belts. Except he said that I provided the incorrect belt fot the AC. And he bought a duralast sor the AC. Yeah yeah I know easy job...not so easy in cold weather rolling around in the gravel of your driveway (big whine). Any way long story short 3 days after replacement bang three of four belts self destruct on the road,left me with a single alt/waterpump belt to limp home. I found the duralast AC belt wrapped around the fan and pretty well shreded. The other WP/ALT belt looked as if it had been sheared in two and the PS belt was loose in the engine compartment. So any guess what happened ? Bad work, bad belts ? Karma ? The phase of the moon ? What could cause this ? Maybe one belt failed and took out two others ?

Probably way over-tightened. Keep diesel Mercedes out of the hands of people who can't spell their own name.

Also, check and make sure all pulley's are in alignment. If there is a belt tensioner pulley on your model make sure it is tensioning properly. I post this in addition to forum member pointing at belts improperly tensioned (high or low tension).

A couple of experiences. First, I once had all 4 belts come of my 300D after one failed and knocked off the others. Second, one of my water pump/ alternator belts failed twice after about 10K miles. It turned out that the pulley on the alternator had some nicks in it that were cutting the belts (like someone had used vice grips to hold the pulley.