280SE A/C Configuration Photo Request
 

Hi...I was hoping you guys could kindly help me. I just purchased a 1970 MB 280SE with the M130 engine. At some point, a previous owner removed the A/C hoses, compressor bracket and pulley. I'm trying to restore these pieces in prep for a Sanyo compressor and R134 upgrade. I found a compressor bracket on ebay, but I have no idea what the correct idler pulley looks like or where it is located on top of the engine. Is the pulley spring loaded? Is it affixed to the compressor bracket or the head? I would be most indebted if anyone with installed A/C could kindly post a few pictures of the pulley and the attachment, with belt routing. The configuration for the M130 on a 280SE is different than a 280SL, where the compressor is down low. Any help most appreciated. Many thanks! Joe

There were a few different configurations, depending on who did the install.


This was the most commonly used one. It was a big, clunky, massively over-engineered chunk of metal which made it an extremely difficult task for any minor maintenance on the RH side of the engine. Belt tension was achieved by an idler pulley which was mounted to the bracket.

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Hi Mike...that's it...is it possible to see the idler as mounted to the bracket? I found one on ebay that is a rigid structure without spring loading...I think this is the correct one used on a number of early cars...thank you...

The rigid ones were used then. You would use a big wrench, like a Cresent wrench, to grab onto the idler wheel holder. Then you would loosen the bolt holding the idler assembly. This bolt is behind the mounting bracket.

Then you would adjust the tension on the belt by moving the entire assembly up or down and when you had it where you wanted it you hold it in place and tighten the bolt.

This is a very simple system but it is easy to over tension the belt and cause undue wear on your idler pulley bearing. So tight is good on the belt. Piano wire tight is a bit too much.

When you see it in person it is easy to figure out.

By the way, the idle pulley is a special one that Mercedes uses since it has to fit the bolt that goes through the middle of the idle pulley. This bolt has a taper to it. So don't try to pick a pulley up at a hardware store and expect it to fit.

The good news the pulleys are very high quality so when you install a new one you are usually good for the next ten years.

Look at pictures of completed auctions on BAT. it is a great resource. Some of the auctions have very detailed pictures.

Is this the correct pulley? I found this on Ebay...

You need to check the mounting bracket for threads. There were at least two versions of the mounts. One has threads in the pulley assembly, the other has the threads in the bracket. The most commonly used one has the threads in the pulley arm assembly.

Bracket, idler pulley and adapter plate photo's

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Pictures #4 and #5 show the idler pulley arm. The arm shown mounted on the bracket is the pulley assembly without the bearing and pulley attached. The loose pulley assembly is the compete unit.

The ones with the with the threads in the pully arm assembly are the most popular since they are the easiest to adjust.

By the way.... Not that this is important, just interesting, but many if not most of the brackets, known as the mount assembly, were made by a company in Arlington, Texas, called Acme Machine. It went out of business years ago. Acme also made a lot, if not all, the mount kits for ARA. Both were owned by Textron.

I think the Thermoking units, the ones from 1967 back, used a few made in their factory. This is why there are two different mounting brackets out there. There were a lot of Thermoking mount kits left to use up when Mercedes switched over to BEHR.

Hi...this pulley has no threads in it...just a loose through bolt...I'm assuming this is just used with a bolt and a through hole in the bracket...speaking of which, when looking at the bracket, I can't see any wear points on the surface indicating where a pulley may have been...do I need a pulley that is threaded then?
Interesting about the pulley vendor...when you said Acme Machine, I suddenly thought of the Coyote and Road Runner LOL!

Is this the correct pulley orientation? The thick washer that came with the pulley was too thick to use and be mounted given the length of the bolt and the thickness of the bracket...I know the bracket is correct for the M130 used with the 280SE...