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Belt Sizes

2K views 32 replies 9 participants last post by  Aussiemerc 
#1 ·
I have taken off my three belts and now I can see what size they are... and they don't match with the FSM. In addition Autohaus only sells one of the sizes that I have taken off my vehicle.

FSM says:

2616726


I removed:

A = not installed on my vehicle
B = AVX10 x 1170 La
C = AVX10 x 1035 La
D = AVX13 x 875 La

One issue is that I have tried and failed to see my engine serial number so I can't be sure which of the three B belt sizes and which of the two C belt sizes I am supposed to use.

So the question is - replace with the same sizes as I removed or try to work out the correct sizes and go with them?

Thanks, Andy
 
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#2 ·
I just went through this with my M116 w108. I ended up using 11a1180 for the twin drive belts (belt B?), but if your car hasn't been modified, I'd use the factory spec belt. My local shop measured mine, and gave me the wrong one, then i convinced him to give me the one available that was closest to factory spec one. Turns out the one that was already on the car was wrong, and power steering pump was fully adjusted out, and the tension just wasnt quite there the whole time i've owned it...
The alternator belt seems to have plenty of adjustment on the m116 and m117, so not so critical in my opinion.
 
#3 ·
The old classical "narrow" v-belt (9.5, 12.5...) has a slightly different form from the newer AVX belts. The are interchangeable as far as pulley fit but the length designation will be a bit different for belts of the same effective working length. I used to have some technical information this but I don't know if I can find it.
 
#4 ·
I recall that at least one of the belts on my 72 had different belt profile than the later standardized shape. I recall buying aftermarket belts from local auto supply shop that did not fit properly even although length was correct. I ended up buying belts from dealer. They worked fine and actually cost same or less than the Gates (or whatever they were). I would recommend buying from dealer or at least Conti belts that match the MB part number.

By the way Andy, if you have the datasheet for your car, it should show the original engine number. Or dealer should be able to pull it up from VIN.
 
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#7 ·
Too bad about that new $150 charge. The engine number is hard to find and see. Rowdie posted a pic at one time of where it is. I could see it was there, but couldn't read it. I knew the number anyway :) Maybe dealer can give you the number from VIN.
 
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#19 ·
Thanks to roncallo for giving it a try. I called my local MB dealer and all they could find in their system based on my VIN that might be the engine serial number is 11798212029615.

I immediately recognized the first six digits, so breaking this down:

117.982 = M117 D-jet
12
029615 = serial number?

But they were not sure if the last six digits is the engine serial number. However I then asked them what size belts and now they are researching it and will get back to me. LOL. Seems it is confusing for them as well.

Andy
 
#21 ·
So this is quite confusing. Going by the engine serial number of 029615 I get from the EPC:

B - 9.5x1160 - A0069973592 (10mm shorter than I took off)
C - 9.5x1025 - A0059975692 (10mm shorter than I took off)
D - 12.5x850 - A0049979892 (25mm shorter than I took off)

however the FSM doesn't show a C belt length of 1025mm. Also the EPC shows that belt D (for the A/C) does not apply to my engine.

Andy
 
#22 · (Edited)
Andy, are you entering car's vin on epc, then finding different belts for different engine numbers? I found that info somewhere for my car. I will check in morning. (On phone now) There is of course adjustment so 10mm may not be a problem. By the way, from dealer I think the ps belts came as a matched pair.
 
#29 ·
Well this is annoying. The PS pump belts are far too big (1160) even with the PS pump rotated outwards as far as it will go. And the A/C belt is too small (850) even with the idler pulley rotated in so far it touches the crankshaft pulley. Sigh.

It's weird how none of this makes any sense.

Andy
 
#30 ·
It's weird how none of this makes any sense.

Andy
Sorry to hear that Andy.
If the shorter choice for ps is too long, only things I can think of are that pump is not where it should be or belts are on smaller diam pulley. Is that even possible? I will have to look at diagrams. How do new belts compare in length with old ones?
 
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