W126 Mercedes 300SD Air Conditioning Belt Noise - Loose Belt or Bad Compressor ?

#impalamansgarage
In this video I will show you how to determine whether or not your drive belt noise is due to the belt or the accessory. It's simple !
Sep 13, 2019 Update
Based on advice I obtained from Pierre Hedary I ordered and installed a genuine Mercedes AC belt. p/n 004-997-93-92. I tightened it thoroughly. The AC belt problem was eliminated. The over the counter belt I installed was ribbed underneath as are most cheap belts. I assume this is to save manufacturing cost and possibly make the belts lighter. (who knows) The Mercedes belt was solid and much more substantial. Highly recommend genuine Mercedes belts for your classic Mercedes.
#Mercedes 300SD
#OM617
#W126

[@sr22dvr]

Thanks for the video. My 300SD makes the same exact noise. A local classic MB shop said it was the compressor going bad. Ordering the belt today!

[@ImpalamansGarage]

Once I put a good belt on it and got it tight I've had no issues. Cheap belts will flop around.

[@ImpalamansGarage]

Yes, the belt is tight.

[@Leo.Rod1989]

Man I wish i would have seen this video sooner. I was having issues that may just be this problem. I got frustrated and ended up cutting the belt off. I had just replaced the compressor. Ac had not been used for at least 10 years. Took the old one out and shook the compressor, and it had metal in it. It was rattling. Anywho. Replaced it with a new one, made sure the pressure was good.

[@Leo.Rod1989]

The belt didn't start making noise till like 3 mins after. And I'm sure this is it. I order a belt from the same brand compressor so I hope it solves the problem

[@tyronh2896]

Did it solve your problem?

[@h.v.g7882]

This is my problem also. I replaced al the belts last week. From a "o'reilly" in Holland. Also not original. And on my 300SD I hear the same noise. And that's to you, I know what the problem is 👍👍👍.

[@ImpalamansGarage]

Take a look at the Contitech belts by Continental. Which ever belt you choose, you must ensure that the it is tightened to the proper tension. The AC compressors are picky.

[@h.v.g7882]

@ImpalamansGarage I replaced al the belts. And without any I tightened to a point that I think it wad oke. And they the strange noise 🤔. I thought it wad the ac clutch, luckily I found your video 😃. I tightened the belt really tight. That I found out in 1 of John Woods video's. The belt must be really tight otherwise you get the strange noise. And for me it fixed the problem

[@ImpalamansGarage]

Based on advise I obtained from Pierre Hedary I ordered and installed a genuine Mercedes AC belt. p/n 004-997-93-92. I tightened it thoroughly. The AC belt problem was eliminated. The over the counter belt I installed was ribbed underneath as are most cheap belts. I assume this is to save manufacturing cost and possible to make the belts lighter. (who knows) The Mercedes belt was solid and much more substantial. Highly recommend genuine Mercedes belts for your classic Mercedes.

[@wernerdanler2742]

You just hit on a problem I had with my 85 300D. The parts store belts are to narrow as I discovered. However, the MB belts are almost to short to get on the pulleys even though they are the right width. The real problem I had though was that they would come loose after about a month or two. The compressor slide bolt has a lock bolt to keep it from loosening yet the belt would come loose and start making a banging noise. I would reset it tightening the belt without over tightening it then lock down the bolts on the compressor. It continued to do this till I sold the car. As far as I could tell the belt was not stretching. The pulley may actually have been out of round but I don't know. Drove me nuts, well nutier!

[@ImpalamansGarage]

Buy the Mercedes belt for the AC Compressor and get it tight. Perry Hedari words. He was right. Fixed my issue.

[@johnharbour3158]

Thats a power steering pump

[@ImpalamansGarage]

Yeah you can't really see the AC compressor in the thumbnail photo. All you can see is the PS pump. I was pouring water on the AC belt down below. On these cars the AC compressor is directly below the PS pump.