The W123 chassis covers 240D's, 300D's, 300TD's, 280E's, and several other models of Mercedes coupes, sedans and wagons from model years 1977 to 1985.

81 Questions View all

How to change the motor belts

how to change the motor belts (water pump / power steering / air condition)

Answered! View the answer I have this problem too

Is this a good question?

Score 2


I have this problem too, but have no idea how to begin. Can someone give me pointers. I need to know how to replace all belts. Which comes out first, etc. And how to make sure that the belts have the right tension.


ony632000 What year is your car


ony632000 if your car is a W123, take a look at the answer I gave below. There are links directly to the instructions in the factory service manual for replacing the belts. Generally, you will be removing 1) the power steering belt 2) water pump and alternator belt(s) and then 3) the A/C compressor belt in that order assuming your car is equipped with all of those items. Removing the is fairly easy - loosen (do not remove) the bolts holding the item in place (be it the power steering pump, the alternator, or compressor) and then loosen the adjusting bolt to move the item towards the engine as needed until the belt is loose enough to get over the pulley. Installing the new belts is the opposite, but can be a bit tricky as the new belts are often a bit tighter than the old belts. I've always just done the tension by feel and been alright. Always check them a few times after installing the new belts and tighten as needed - they will stretch a bit at first until they settle in.


Dear Nicolas, thank you so much for your help. I am even more appreciative of how quickly you responded. God bless you. I will let you know how it went.


Add a comment

2 Answers

Chosen Solution

Hello, in regards to changing belts on the W123 chassis, there are a few differences between model years. For example, the early model years (1977 and 1978) use a different A/C compressor and the method for replacing that belt is different than on the later models. So it would be helpful to know which year you have.

However, in the meantime here are some links that may be helpful. They are PDF files from the online factory service manual. The first is for the early style belt setup with the older compressor, the second is for the newer style. If you read the documents they help you identify which you have.

I will probably do a guide on this with full picture instructions next time I do something like replacing my water pump on one of my W123's. Look for that.

Was this answer helpful?

Score 3
Add a comment

I maybe a auto electrician, but there should be a spring loaded pulley put a correct size spanner and leaver on it apply force to spring it back and remove the belt.

A make and model and year would be helpful.

Was this answer helpful?

Score 0


Hello, just wanted to mention that the W123 chassis is not set up this way. It does not have a single serpentine belt with a belt tensioner, unlike newer cars. Instead it has a set of V-belts that are tensioned manually by the installer using tensioning screws on the various accessories. The power steering and a/c compressor belts are tensioned by moving those devices in/out on their respective brackets. The water pump and alternator share a v-belt which is tensioned by the alternator - the water pump does not move and is not adjustable. Thanks for the input though.


Add a comment

Add your answer

magdyshoukry will be eternally grateful.
View Statistics:

Past 24 Hours: 2

Past 7 Days: 13

Past 30 Days: 136

All Time: 6,276