Single or Dual groove alt pulley? W123 '84
 

Um... I'm going to change my belts tomorrow and I purchased four quality belts. Go to look what I'll be getting myself into tomorrow and the agua pump pulley appears to have two grooves while the alt pulley has a single?! :confused:

Is this normal or has my alt been replaced and consequntly gotten a non OE pulley? Or is something else amiss I'm not aware of... ;) Seems odd why the H²O pulley has dual grooves to me. :confused:

If it is indeed supposed to have a dual groove pulley, would it be in my best interest to install the proper on in its place?

Thanks!

Dual
 

I have a 84 300D also, mine has a dual pulley on the alternator. Before you begin read the DIY pages. Wwith all of the adjusters on all the pumps, it is not like changing belts on a American car. Good luck.

Your alternator should have a dual grooved pulley, two belts means more surface area so you can get away with less tension on the belts, which means a longer life for the bearing involved. It also gives a degree of redundancy!

I did my belts two weeks ago, you need to loosen the mounting bolts on the power steering pump, a/c compressor and alternator. Having done this you need to slacken off the adjusting nut on each of these components, and each of them is different. The alternator is probably the most obvious one to identify, assuming that you still have yours - it's a threaded rod attached to the upper mounting that allows you to pull the alternator tight. There's an adjustor on the top of the p/s pump and a rather awkward 10mm one on the side of the a/c compressor which you get to from above - I used a flex drive on a socket handle.

It's really not a tricky job providing you locate each of the adjustors and back them off a good bit, old belts come off and new go on quite easily. Adjust the belts using the adjustors, then lock down the mountings.

Mine is a 300SD, but I'm assuming that this is common to all of the '80s 617 installations.

Kevin

From my observations, W123 240Ds and na 300Ds had a single belt connecting the water pump and alternator, and the W123 turbos have two.

I was going to read through my repair manual first actually just to be sure of what to do. :D

Appears as though I'm going to find a dual groove pulley here and install it now.