83 300D W123
I am trying to tighten up the pair of belts used in this thing. I can't seem to get the alternator to move at all. I am wondering if I'm screwed up here. I found a 17MM bolt under the car, very near one of the A/C lines and loosend it. Now this gooofy looking adjuster nut up top, which way to tighten the belts? Neither way seems to do anything and I'm don't want to snap anything. Is there another bolt to loosen besides the one at the bottom of the alternator? These belts are pretty loose and I suspect they are the cause of my car running a little warm at times.
Any help, greatly appreciated.

there is a bolt on the top of the alternator bracket (right next to the main pully) that you need to loosen up. then the tension adjuster should work.

__________________
1984 300D Turbo - 231k....totalled 11/30/07 RIP

rmmagow,

A 17 mm bolt? I dont think there is such an animal. Possibly you mean something like a 10 mm bolt with a 17mm hex head. FYI the size of a bolt is determined by its diameter ( and thread pitch) not the size of the hex head.

P E H

The top alternator bolt is shown below. To tighten the belt, loosen the large nut on the back of the top bolt. Also loosen the bottom alternator mount bolt, which it sounds like you've already found. Then tighten the smaller nut on the adjuster until you get proper belt tension.

Once you get the belt tight, tighten both the large nuts. At this point I think it is a good idea to back off on the adjuster just slightly to take the stress off it.

I had a heckuva time adjusting my 240D, and even broke the adjuster bolt. Upon complete removal of the alternator, I discovered that the top hole had been ovaled out, allowing the alternator to cock sideways and get stuck. A rebuilt alternator solved that problem. Just a personal experience for you information.

Attached Thumbnails

 

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

Thanks all. Nice and tight now, what a PIA this car can be for simple things.

And PEH, quit bustin' my chops, remind me of my old man :-)

rmmagow,

I'm not busting your chops, just telling you how to describe a bolt correctly probably like your old man did and you didn't listen.

BTW, I like the screw adjustments on the alternator, PS pump and AC compressor. It sure beats having to use a prybar while trying to tighten the bolts.

P E H