Hi there people, so I've posted a few things to the forum, but I'm just your average new 300D owner and now I have my first real question. And, I searched the threads but didn't find exactly what I was looking for.
I had my car in the shop today and one of the service guys pointed out that I only had one belt on the dual pulley connected to my alternator. I know the A/C compressor went kaput on the previous owner, and he just decided to have it disconnected (not a problem for me, I don't care about A/C here in Seattle). My question: is it okay to just have the one belt on the dual pulley or does the other belt serve a greater purpose than to just power the A/C? Does it do that even? Car runs great, btw. Thanks, I appreciate anything you'd like to tell me!

-Joe

__________________
1984 300D, 228k, Light Ivory, Java MB-Tex

The AC is powered by its own belt, there should be a total of four belts (AC, steering pump, and two for both the alt and water pump). You can get away with a single belt for the alt/water pump if it's not slipping, but you are better off with two new belts. It's a fairly easy/cheap repair.

Okay, great. Thank you for the quick reply. The belt for the alt/water pump is not slipping yet, but I'll add the other belt.

__________________
1984 300D, 228k, Light Ivory, Java MB-Tex

My 2 crents worth:
I had wondered why there are 2 belts on such a low Amperage Alternator on my Car and I concluded that there are 2 belts because the Alternator is mounted low and subject to water spray. Of coures I do not know the real reason.

Another reason to use 2 belts is that if you only use 1 belt that Pulley were wear more than the unused on. If after a long period of time you decide to go back to 2 belts you will only be able to tension one of them.

__________________
84 300D, 82 Volvo 244Gl Diesel

I don't think that the pulley really "wears" all that much....its hard polished steel vs. rubber.....

MB used two belts because its MB, extra overkill. With two belts if one fails you can continue unimpeded, with one, not so much.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Over time the pulleys can wear. It takes a lot of miles though. If you look at the profile of a worn pulley it will look like a U instead of a nice V.

-Jason

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I ran with one alt belt for a while because I couldnt get the double pulley off of the original alternator but after I got my AC fixed the Alt belt would slip when the AC compressor was running, with a impact I got the double pulley off and with 2 belts I had no issue.

__________________

1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

Considering the alternator spins up 8-9,000rpm I would think it needs 2 belts.

It is not necessarily needed to run the car, the car will run without an alternator. It's just for accessories. Other than headlights at night or wipers in the rain.
You don't really need ac or the windows to go up & down or the sunroof to open!

Danny

__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination

Agreed, mostly, yet as mentioned it also powers the water pump.
J_C, when you get to it, put two new ones on instead of having an old and new belt.

__________________
83 SD

84 CD

The primary advantage of two belts is that it permits a 50% reduction in belt tension. That's a very good thing when it comes to accessory longevity.

There are millions of cars, trucks, airplanes and tractors that get by with one belt.

I have been able to drive home a couple of times after having one belt fail, I so like the redundancy of two belts. If you are going add the belt, replace them both at once with the correct size, not the equivilant size from the auto parts store.

considering the fact that the two belts run your water pump and alternator, two belts is great security.

__________________
1981 300SD 512k OM603

I agree. It was designed for two so I would not use one for very long. I suspect it might have some effect on the bearings too since the force on them would be not what it was designed for.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Buy them at the same place.I have one Gates,and the other? You can't tighten them both if different brands.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

This is some good input. I'll put two new belts on there soon. Too bad there's not a space for a third belt...or a fourth ... or a fifth ...

__________________
1984 300D, 228k, Light Ivory, Java MB-Tex