Changed A/C Compressor Belt --- Way Too Tight - PeachParts Mercedes-Benz Forum

bluetypewriter · #1 04-15-2010, 11:49 AM

W123 1982 300TD

I attempted to change all my belts last night but ran into a snag when trying to get the A/C belt on. I loosened all three retaining bolts as well as the tensioning bolt and pivoted the compressor until it was bumping against the engine. The belt was too tight to pull onto the pulley by hand so we cranked the engine to put the belt into place.

The problem that the belt is way too tight; I can't physically move the compressor back into place so I can re-tighten the mounting bolts.

I've confirmed with my manual and with the PeachParts store that I'm using the correct belt. It's a 13 x 925. I compared it to the old belt and it matches, but the old belt was extremely tight as well. I had to cut it off.

I'm pretty sure I have it on the right pulley. If you're looking down at the engine while standing in front of the car the belt order on the engine goes Alternator, Alternator, A/C, Power steering (from top to bottom).

In short, I'm having the exact same problem as this guy.

Here are some other threads I've read but for some reason I still can't get it.

A/C belt fitment
http://www.peachparts.com/shopforum/diesel-discussion/62696-need-help-c-belt.html#post384877

I think when I get home I'll remove the belt, remount the compressor, and try again. But I thought I'd type all this up while I'm sitting in my cubicle so I can get my thoughts straight.

leathermang · #2 04-15-2010, 12:26 PM

Putting unorganized thoughts here in the hands of perverse strangers will surely get them scrambled and toasted.... but we will have fun doing it..

Naturally there is a gauge MB uses to measure the ' tightness' of the belt... a measure of the deflection under pressure... perhaps you have missed a bolt intended to allow more movement of the bracket .... that has happened many times here on the forum...

bluetypewriter · #3 04-15-2010, 08:00 PM

I attempted to remove the belt so I can remount the compressor but it's too tight. I think I'm going to have to cut it off.

Photos!

Gap between tensioning bolt and compressor

Compressor

Rear of compressor showing removed bolts

Crankshaft, showing positioning of the belts. The A/C compressor is toward the top of the photo

View of loosened compressor

Crankshaft on bottom, A/C compressor on top. Shows how they are currently bumped together

Okay, so what did I do wrong?

Thanks everyone

layback40 · #4 04-16-2010, 08:20 AM

It looks like that belt is just too small for your particular motor. Maybe something was changed in the past, like the pulley on the air con compressor.I dont think you have done any thing wrong. Looks like you need a 13 x 935 belt on your motor. Is that tensioning bolt adjusted up as far as it can go?

vstech · #5 04-16-2010, 08:27 AM

you took the refrigerant lines loose?

bluetypewriter · #6 04-16-2010, 08:47 AM

Quote:

Originally Posted by layback40

Looks like you need a 13 x 935 belt on your motor. Is that tensioning bolt adjusted up as far as it can go?

Thanks. I'll try that.

Regarding the tensioning bolt, it's completely separated from the restraining bolt. You can see the washer end of the tensioning bolt in one of the photos.

bluetypewriter · #7 04-16-2010, 08:50 AM

Quote:

Originally Posted by vstech

you took the refrigerant lines loose?

I don't think so, unless the refrigerant lines connect at the rear of the compressor near the bottom. Either way, the PO told me that there was no refrigerant in the car. I didn't hear any gas escape while I was playing with it.

vstech · #8 04-16-2010, 08:57 AM

Quote:

Originally Posted by bluetypewriter

this photo shows the lines disconnected
Rear of compressor showing removed bolts

as does this photo

View of loosened compressor

how many bolts did you loosen on the back of the compressor?
there should be 4 including the bolt that holds the adjuster loop.
take a photo of the back side of the compressor lets see if you forgot a bolt.

bluetypewriter · #9 04-16-2010, 09:24 AM

Quote:

Originally Posted by vstech

how many bolts did you loosen on the back of the compressor?
there should be 4 including the bolt that holds the adjuster loop.
take a photo of the back side of the compressor lets see if you forgot a bolt.

I think five. Three large restraining bolts and two small bolts near the lines. One of the smaller bolts was also restraining and the other held the lines to the compressor.

I'm in my cubicle now but I'll ride the bike home during lunch and take a photo.

bluetypewriter · #10 04-16-2010, 12:30 PM

I couldn't get the correct angle for a wide shot of the back side of the compressor. Here are a series of photos with a pencil pointing to each removed bolt.

Smallish bolt that holds the refrigerant lines to the compressor

Smallish bolt directly below the one pictured above. Connects compressor to some sort of arm

One of three large bolts. Located in rear, closest to the engine

Second of three large bolts. Located on rear, closer to the top, furthest from the engine. Attaches to tensioner.

Third of three large bolts. Located on the rear, near the top of the compressor. This is the only bolt I have not removed, but it has been loosened.

Another view of the tensioning bolt. The bolt is removed so you can see the washer

Hopefully these photos help.

My current plan is to cut this belt, remount the compressor, and try again with a larger belt.

leathermang · #11 04-16-2010, 12:39 PM

Your pictures are amazingly focused.... but you need to supply some LIGHT in there too..

bluetypewriter · #12 04-16-2010, 12:52 PM

I'll get in there with a shop light. The flash over exposes everything

leathermang · #13 04-16-2010, 01:11 PM

Most digital cameras have a feature where you sqeeze slowly and it does better with ambient light... give the camera a chance to adjust for low light situations better...

Tom Wing · #14 04-16-2010, 01:42 PM

Quote:

Originally Posted by leathermang

Most digital cameras have a feature where you sqeeze slowly and it does better with ambient light... give the camera a chance to adjust for low light situations better...

YOu are correct, most cameras (digital) allow you to do this. Hold the shutter button down half way, most cameras will make a noise or something like that and then depress it all the way.

the feature you are talking about is the one that is the picture of the flower, and you are also correct, it will not only focus across the shot, but attempt to correct the light imbalances.

bluetypewriter · #15 04-16-2010, 02:01 PM

Quote:

Originally Posted by leathermang

Your pictures are amazingly focused.... but you need to supply some LIGHT in there too..

What specifically would you like to see?