I am replacing my alternator in my 300SD. I went to a local rebuild shop, and they had one that was identical, but the pulley is only for 1 belt, not two.

When I look at the car, it appears that the two belts connect from one double pulley to another double pulley. It was the same in my 300TD when I had it. What's the purpose of that? Could I get bye with just one belt?

thanks

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In case one fails. It also turns the fan. Its one of the few weakpoints of the NA 617...

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

The NA 617 has only one belt, the turbo has two. at least on my cars.
two belts give you more surface area to handle the load of the massive 65A alternator...riiiight. OM vehicles tend to get oil on everything. maybe MB decided that slippage might be reduced with the extra belt... cooling is important.
John

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Why not just swap the double sheave for the single on the "new" alternator? Very easy for a rebuild shop... RT

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When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

I would if I could... the nut fell off the shaft and the shaft and pulley were damaged in the process... the alternator is probably fine electrically.

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My daughters 240D has one belt. It broke and so the water pump does not turn. My daughter was stranded on the side of the road comming home from college.

300TD has 2 belts. I had one break and the other one is fine. So the car can be driven and no overheating. I have a new set, I just haven't installed them.

I would install both belts just for peace of mind.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

Two belts is a great idea. The only thing better is a serp.

I had 'matched set' belts on my Merkur. They lasted forever.

If one breaks, you'll make it home. Two belts seem to grip better than one.

You can run a lower belt tension, which is good for the bearings.

Serpentine belts, which are fairly new to me, are fab. It sort of scares me that I might eventually throw one, but so far I haven't.

ok ok two belts it is...

So, anyone have a spare double pulley laying around???

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not exactly a spare, but I have 4 parts cars... pm me.
John

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Its typical Mercedes overkill. Things like that are why they cost more.

Sure you can get by with one V belt, most cars do. But Mercedes takes it a step further, having a second is better. Most cars lack them because such a set up costs more, but the engineers spec'd two because cost wasn't an issue.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

That double belt has saved me a couple of times, it will run with one, but it will slip unless it's pretty tight. Last time I broke one I was in VT, and I drove around for a week before I had a chance to replace it. Sure beats having to do it on the side of a highway someplace.

On a Merkur, the belts surely last longer than the motor.......

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Well put!!

Liebchin....because ve zaid zo........

SB

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Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG

Also kudo's to Mercedes for making the belts cheap. Last I checked I think replacements were like $10 each!

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200