Lately, I can't seem to keep the belts tight on my alternator. I have to retighten them about every 3 days. This is getting very old very fast. I recently replaced the belts and all the accessory mount bushings in the alternator and top bracket, but this isn't helping much.

I have a belt tensioner that came from a later model 240 and would like to install it on my car (1980 242, B21 which never had a belt tensioner for the alternator) but I don't know how this tensioner goes onto the alterntor. The tensioner I have is simply a small metal block with a hole of roughly 9mm diameter through the face of it, and a fairly long bolt (8mm dia by 75mm long?)that is threaded throught the side of the block at 90 degrees from the face with the hole.

Does anybody have a picture of how this tensioner goes, or a link to a picture, or a really good text explanation of how it installs? I've searched the archives here, and also google-searched for over an hour with no luck. I'm tired of hearing the squealing and smelling the rubber burning as the belts slip on the pulleys, not to mention the beating my battery is taking from not getting properly recharged...

Billy McCaskill
billy242
1980 242DL with lots of GT and IPD stuff

Hello,


You may not be supplying adequate tension to the alternator belts, Bill.

The later alternators have may have a different casing. I DON'T think you should replace the alternator or tensioner because of your difficulty.

You need to purchase the largest Channellocks and grab the case of the unit and then apply pressure to the belts whilst tightening the locking nut.

If you are using your hand to tighten the belts, then you are doing it wrong.

I don't know how you are trying to tighten the belts. If you tell me more about what you are doing, I may be able to help you further.

Thank you for your time and effort posting your problem on the Brickboard forum. We all appreciate the valuble information to learn from.


Goatman

I wasn't planning on replacing my alternator as it's charging just fine. I just want to install a tensioner on it to help keep the belts from loosening up. Not sure why they are loosening up so much lately. I am using my breaker bar as a lever between the alternator case and the engine block to put significant tension on the belts while I tighten up the top alternator bracket bolt. I am tightening that bolt about as tight as I think a poor little old 8mm bolt can be tightened without breaking. Yet the belts will be loose in 2 or 3 days...

I guess I will just go outside and see if I can figure out by myself how that tensioner can be installed, there can't be too many ways for that thing to go in there.

billy242
1980 242DL with lots of GT and IPD stuff

Are you also tightening the Lower 'Pivot' Bolt?

As far as the new Tensioner, it sounds like you are missing another piece.
The Upper bolt that you are now tightening passes through that Block on your new tensioner.
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

I agree something else is going on here. The jackscrew arrangement is only an evolution from the crowbar approach for adjusting the top bolt position in a slotted bracket. It plays no part once the adjustment is made - just makes the tech look better without a pry bar in his left mitt.


--
Art Benstein near Baltimore

To write with a broken pencil is pointless.

Wow, thanks Art. This is exactly what I was looking for. I thought that perhaps the jack screw actually pressed against the side of the engine block to provide the tension. The upper alternator bracket shown in this picture is the part that I am missing, and thus the reason for my not understanding how the block/ jack screw arrangement worked in conjunction with my current upper alternator bracket which does not have the 90 degree bend with a hole in it.

I've seen some pretty neat adjustable top alternator tensioner brackets on hot rods at car shows, maybe I'll try to duplicate something like that to help maintain the tension on my belts.

And yes, I am tightening the bottom bracket bolt too. Still not sure why my belts won't stay tensioned properly...

Billy McCaskill
1980 242DL with lots of GT and IPD stuff