I have an 83 240d how would i tighten up the serpentine belt? I have been told the three 17 mm bolts on the back of the alternator, but what do i do with them?

You have a 240D with a serpentine belt? Got pics?

It should have three (IIRC) V-belts.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

You have the old style V belts. If you look at the alternator, there should be a slide track. You need a big screwdriver or prybar. Loosen the bolts some, pry it until the belt is tight and retighten.

I highly recomend you get a service manual. Haynes, Chilton, or the factory manuals will have pictures and step by stepinstructions for both basic and more difficult maintanance tasks.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

I believe all OE 123 MB alternators have some kind of threaded or geared mechanism for tightening the alternator once the bolts are loosened.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

My 82 240D has three bolts to loosen, then one to tighten/loosen the alt position . . .no serpentine belt on mine

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82 240D Manual 277K and still rolling!
02 Volvo S60 AWD For Sale

even the ones with the m102 engine?

He has a 240d which is the 616. Kerry is correct, loosten the pivot bolt on the bottom which is a little tricky to reach and then turn the adjustment bolt until you have the belt the way you want it and then cinch down the large 17mm bolts on the bottom. Its the nicest working adjustment setup on v belts I have ever seen. Buy quality belts, install them and they will last decades. (Well, almost).

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[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.

LOL, decades?

Actually, I like to replace mine in the fall to minimize the possibility of one failing in the middle of winter. I'm sure they will actually last several years for most people.

Here is another thread on tightening the belts.

I posted a couple of pictures in post #5.

www.peachparts.com/shopforum/showthread.php?t=260389

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

With the mileage you drive once a year is like once a decade for most people!

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[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.