adjusting the belts - PeachParts Mercedes-Benz Forum

80300dbenz · #1 03-31-2006, 05:04 PM

How do I adjust the alternator belt on my 1980 300D it is very loose?

rhodes2010 · #2 03-31-2006, 05:11 PM

1. 17mm wrench, loosen the nut at back of alternator, top of bracket.
2. Use 13mm (I prefer socket) to turn ClockWise (CW) the long nut
sticking straight out towards the passenger side at top of alternator.

Retighten nut on back of alternator.
Sometimes..... the nut at bottom of alternator is very tight and will not allow
alternator to rotate. Crawl under car at front bumper (no jacking needed)
and loosen the 17mm nut at back of alternator with wrench.

80300dbenz · #3 03-31-2006, 05:44 PM

Do i loosen all the bolts behind tha altanator?

#4 03-31-2006, 05:58 PM

Quote:

Originally Posted by 80300dbenz

Do i loosen all the bolts behind tha altanator?

There is on bolt at the bottom (the pivot point) and one at the top (in an adjustment slot) that should be loosened. When they are both loose, turn the adjuster nut (attached to the front of the top bolt) clockwise to tighten the belt.

80300dbenz · #5 03-31-2006, 09:10 PM

how does that bolt in the front work? i keep on tightening it but doesnt seem to get tight.

Brian Carlton · #6 03-31-2006, 09:15 PM

Quote:

Originally Posted by 80300dbenz

how does that bolt in the front work?

Which bolt are you referring to? One of the large mounting bolts? Or the very light duty adjustment bolt with a nut on the end?

80300dbenz · #7 03-31-2006, 09:21 PM

the one closest to the fan shroud its a 13mm

Brian Carlton · #8 03-31-2006, 09:26 PM

Quote:

Originally Posted by 80300dbenz

the one closest to the fan shroud its a 13mm

That bolt should have a nut on the end of it. The nut bears on the two prongs of the bracket. As you tighten the nut, it forces against the bracket and draws the bolt toward the passenger side of the vehicle. The alternator comes with it and tightens the belt.

Don't go crazy on the belt tightness or you'll severely deform the bolt. It's not made of the best materials..........

80300dbenz · #9 03-31-2006, 09:33 PM

that bolt is long right ?

Brian Carlton · #10 03-31-2006, 09:38 PM

Quote:

Originally Posted by 80300dbenz

that bolt is long right ?

Yep, it's right in front of the alternator and extends from the center bolt on the alternator all the way to the right side of the bracket. It's a rather small bolt..........8 mm IIRC.