1985 300D Alternator - double pulley running on one belt? - PeachParts Mercedes-Benz Forum

Diesel911 · #1 06-14-2022, 12:12 AM

Quote:

Originally Posted by BlueGermanTank

Hey all, first time poster.
I recently changed out my alternator and all my belts in the process. Unfortunately since I haven't been able to find a matching pair to replace the ones that go on the alternator double pulley. What I'm wondering is, it's a 65A alternator, and a small water pump. That doesn't seem like a very high load to warrant two belts, except for redundancy.

Is there any reason I can't run the alternator on a single belt? It keeps throwing one of the two, but the other is on snug and the car still runs. I see some old posts saying that it's better to have both, but others saying you can't buy "matched belts" from suppliers anymore.

Wouldn't it be better to run one belt, rather than overtighten two to compensate for slightly different sizes? I have to imagine the bearings would last longer.
Thanks in advance!

The alternator sits low where water could splash up on the belts. That would be my guess why there is 2 belts.

If you run one belt long enough the pullies will not wear evenly and when you put 2 belts on one belt is going to be loose.

tangofox007 · #2 06-14-2022, 10:46 AM

Quote:

Originally Posted by Diesel911

The alternator sits low where water could splash up on the belts. That would be my guess why there is 2 belts.

The crankshaft pulley sits even lower and is common to all belts. Which means that your guess was not a good one.

Dual belts are used to reduce belt tension. No guessing required.

Diesel911 · #3 06-14-2022, 10:07 PM

Quote:

Originally Posted by tangofox007

The crankshaft pulley sits even lower and is common to all belts. Which means that your guess was not a good one.

Dual belts are used to reduce belt tension. No guessing required.

If the crank pulley and the alternator pully both get wet the situation much worse.

We also know that most of the Cars on the road that used V-belts had only one belt and have worked fine like that. But, normally their alternators are also higher up. We also know many have higher amperage alternators that that have the potential to put more of a load on those single belts.