My alternator belt has been squeaking in my '77 300D. It mostly just squeaks for a little bit after I start it up or when there's an extra draw on the battery, such as driving with headlights. I replaced all of the belts within the last year and haven't put many miles on the car. It got so bad that the battery kept dying, so I just took it into a shop to get it over with, after I got it back it was good for a day or two, then started squeaking again, not so bad that the battery was dying, but enough to be annoying, so I took the car back in, they tightened it again (and all the other belts) and same thing, it was good for a day then started squeaking again. I tried using belt dressing spray, it didn't help much, I don't know what else to do other than just replace the belt again, although it seems to be in good shape. Thought I'd go to you all first to see if you had any thoughts, thanks!

Get rid of the junk belts and buy a set of true metric Continental belts.
77 used the tensioner gear bracket, and likely, it's damaged...

__________________
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!

Also, make sure all of the alternator mounting bolts are tight and have the proper washers. Those bolts loosen up fast if the washer is gone and the can whallow out the bolt holes in the bracket if left alone.

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

Bold added for emphasis. THIS.

It was kind of a silly setup IMO. The later 617 alternator tensioning setup was still a bit silly compared to the usual American way of the time, but at least it generally works.

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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.

Agreed. I think the bolt you need is around $5-10 from the dealer. Might be cheaper online.

Can you give a bit more detail on the tensioner gear bracket? I'm not really sure what part you're talking about and the internet doesn't seem to be coming up with answers

if your alternator bracket looks like this...


this alternator bolt may be needed...just click the search window up above, and type 77 300D alternator bolt...



if your bracket needs the gear head bolt, then I don't know where to find it...

__________________
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!

I'm wondering if that later style alt adjustment bracket could easily replace the early style.

__________________
Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

I have a spare gear head bolt laying around from when I had a '77 240D. The OP can have it for the cost of shipping. PM if interested.

__________________
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.

Here's a nice blurry cellphone picture of the bolt in question.

Attached Thumbnails

 

__________________
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.

Pelican Parts - European Automotive Parts and Accessories - Porsche • BMW • Mercedes • Volkswagen • Audi • Saab • Volvo • MINI

^ For the star bolt.

You'll need a different bracket if you upgrade to the "L" bolt pictured in post #7.

First attachment is of the new "L" bolt set up.

The second if of your old star bolt (part #200) set up.

Attached Thumbnails

   

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83 SD

84 CD