Might need alternator bracket 1981 300SD
 

Looks like I might need an alternator bracket for the SD. Does anyone have one cheap? SD is at Pep Boys and they say they cannot install a new belt because the existing bracket is bent and the alternator will not move far enough to install the belt.

Just thinking ahead. Would be sent to Atlanta.

Thx.

I think your Alternator Bracket is the same as a W123 but I am not sure.

It simply could be they don't know how to do it properly.

If they just turn the tensioner nut something is going to bend or break. The need to loosen the 17mm Nut on the large bolt and maybe loosen the Nut on the bolt where the bracket attaches to the cast aluminum frame bolted tot he block.

In the picture the tensioner rod (which is bent a bit) is unscrewed from the tensioner adjustment nut which is hard to see. The nut is retained by bent sheet metal ears which can also bend if the 17mm Nut shown at the bottom of the picture is not loosed before you use the tensioner nut.

Anther common problem is the Tensioner nut gets rusted to the threads and snaps that thin tensioner rod.

In any event if that tensioner rod is out of the nut or it snapped off once the 17mm Nut is loose you can move/pivot the alternator by other means just as you do with alternators that don't have a tensioner.

The key to the thing is that 17mm nut has to be loose before you use the tensioner and then after the Alternator/Belt is adjusted that 17mm Bolt needs to be tightened to lock it in place.

another pic but from the underside of the bracket.

Notice in this pic the part that by the tensioner adjusting nut is bent. That is because the Nut was not loosened on the end of large bolt. If it is bent like that once the Nut on the large Nut is loosened the alternator can be tensioned in a similar manner to all of the Alternators that are on cars that have no tensioner adjustment.

In essence you loosen that large nut and then you get something to lever or pry the Alternator to move it. When you are happy with where the alternator and belts are adjusted you tighten up that nut and lock it in place. And fix the bent part at a later date.

D911 - thanks for that. It has been a long time since I climbed in under to take a look but that looks familiar. But you do not have a spare for a W126?

In addition to D911, the bolt on the bracket that is against the block needs to be loose as well. This allows the alternator adjustment bolt to move all the way in the slot, and tight to the block.

All three 17mm bolts need to be loosened to adjust the alternator belt tension.:)

Pivot bolt for alternator (far right bolt on photo)
Pivot bolt for adjusting bracket (middle red arrow on photo)
Bolt (far left red arrow on photo) for eyelet on tensioner bolt (blue arrow on photo)

Yes, this is a common mistake, and it is almost impossible to replace the belt without loosening all three. Evidently the OP's mechanic does not know this.

Yup, good old Pep Boys.

I would believe old (Pep Boys has been around for decades), but good?

If I was going to have to take one off and put another one back on, I'd just fix the one I took off and save the money. It's nothing a tap and dye set and a little all thread won't fix.

I'd send Pepboys the bill since they bent it. I mean, it worked until they laid hands on it.

You should be able to get one belt on the pulley without loosening the alternator. I saw a guy cut one off an old chevy and put the new one on the crank pulley then pry it partly on the alt pulley with a screwdriver. After he got it good and stuck he bumped the engine and the belt jumped onto the pulley.

I'm not saying that's right and I'm not saying I would do it unless I got stranded with nothing but a good belt and screwdriver, I'm just saying it worked one time on a chevy.

Ya I think PepBoys was around in the late 1950's when I was a kid.

Bump. So does anyone have a spare alternator bracket?