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2008 GL320 CDI - AC serpentine belt By-pass with part numbers
I figured I would share this for reference and helpfulness.
The vehicle was sounding and acting funny after going through some pot holes and muddy water at a work site.
it sounded as if there was gravel rolling around while driving. I thought perhaps it was just some water and mud… it disappeared but returned intermittently.
Roughly two days later there was smoking and a burning odour.
Upon investigating, I traced it to the AC pulley. The AC pulley had sheared off from the AC unit and disintegrated!
You can see that something looks off in the bottom there The pulley in pieces
Using some web searches I tracked down a forum post to someone with a similar issue in Europe and by-passing the ac by using a shorter belt.
They used a Gates 8PK2000 serpentine belt on their ML320 CDI, meaning 8 ribbed, and 2000mm long.
My 2008 GL320 CDI ( OM642 diesel 6-cylinder engine) uses a 7 ribbed belt.
There is a transition from 8 ribbed to 7 ribbed belts and you need to visually match it, or use your VIN to track down the specific part type (if it is 7 ribbed or 8 ribbed) for your vehicle. Usually a simple call to MB parts department and they will tell you if it is 7 or 8 ribbed.
The corresponding part number for me was Gates 7PK2000 (7 ribs, 2000millimetres, etc.)
Now my local Lordco Automotive supplier didn’t have anything close.
I called NAPA and they cross-referenced the Gates 7PK2000 and offered me…
NAPA Power Series
Micro-V
25
070786
7PK1998
Napa belt part # 7PK1998
Since there is no AC pulley (see previous pictures), the belt looped like it normally does and has good tension bypassing the AC pulley.
Vehicle runs better, definitely peppier and should be good for a year once summer rolls around for a potential AC replacement.
Cheers and I hope this helps someone out of a pickle!
Oh,and you can see in the diagram below where the dotted line is, that’s the new route bypassing the AC Compressor pulley.
GL320 CDI serpentine belt diagram
There was a Mercedes TSB on using a shorter belt (with part numbers) for the gas engine to test if the AC Pulley was failing or not, as it was a bit of a headache for MB. There was not one for the diesel… thank god for others sharing!
Also, I’m not concerned about the shorter belt and tension as it is minimal variance.
A friend had a VW 1987 Jetta TD with AC and I had the identical vehicle without AC… my belt was shorter by a bit. No issues to my engine with the shorter belt. That’s my logic
I figured I would share this for reference and helpfulness.
The vehicle was sounding and acting funny after going through some pot holes and muddy water at a work site.
it sounded as if there was gravel rolling around while driving. I thought perhaps it was just some water and mud… it disappeared but returned intermittently.
Roughly two days later there was smoking and a burning odour.
Upon investigating, I traced it to the AC pulley. The AC pulley had sheared off from the AC unit and disintegrated!
You can see that something looks off in the bottom there The pulley in pieces
Using some web searches I tracked down a forum post to someone with a similar issue in Europe and by-passing the ac by using a shorter belt.
They used a Gates 8PK2000 serpentine belt on their ML320 CDI, meaning 8 ribbed, and 2000mm long.
My 2008 GL320 CDI ( OM642 diesel 6-cylinder engine) uses a 7 ribbed belt.
There is a transition from 8 ribbed to 7 ribbed belts and you need to visually match it, or use your VIN to track down the specific part type (if it is 7 ribbed or 8 ribbed) for your vehicle. Usually a simple call to MB parts department and they will tell you if it is 7 or 8 ribbed.
The corresponding part number for me was Gates 7PK2000 (7 ribs, 2000millimetres, etc.)
Now my local Lordco Automotive supplier didn’t have anything close.
I called NAPA and they cross-referenced the Gates 7PK2000 and offered me…
NAPA Power Series
Micro-V
25
070786
7PK1998
Napa belt part # 7PK1998
Since there is no AC pulley (see previous pictures), the belt looped like it normally does and has good tension bypassing the AC pulley.
Vehicle runs better, definitely peppier and should be good for a year once summer rolls around for a potential AC replacement.
Cheers and I hope this helps someone out of a pickle!
Oh,and you can see in the diagram below where the dotted line is, that’s the new route bypassing the AC Compressor pulley.
GL320 CDI serpentine belt diagram
There was a Mercedes TSB on using a shorter belt (with part numbers) for the gas engine to test if the AC Pulley was failing or not, as it was a bit of a headache for MB. There was not one for the diesel… thank god for others sharing!
Also, I’m not concerned about the shorter belt and tension as it is minimal variance.
A friend had a VW 1987 Jetta TD with AC and I had the identical vehicle without AC… my belt was shorter by a bit. No issues to my engine with the shorter belt. That’s my logic
Thank you for this post, it saved my day! :-D By the way, did the repair work in the long term? I plan to do the same.
Just an observation; I measured the length of the belt track with and without the AC pulley and the difference was about 5cm, so that the replacement belt should be less than 2000mm, but it seems that the tensioner has enough working range that it will work....
Thank you for this post, it saved my day! :-D By the way, did the repair work in the long term? I plan to do the same.
Just an observation; I measured the length of the belt track with and without the AC pulley and the difference was about 5cm, so that the replacement belt should be less than 2000mm, but it seems that the tensioner has enough working range that it will work....
that will depend on the tensioner and it’s remaining tension. I used a shorter belt and squeal on occasion. Here is what I used and my thread…
Thank you for this post, it saved my day! :-D By the way, did the repair work in the long term? I plan to do the same.
Just an observation; I measured the length of the belt track with and without the AC pulley and the difference was about 5cm, so that the replacement belt should be less than 2000mm, but it seems that the tensioner has enough working range that it will work....
The person I found the original post from had it working for a year without issue, but your results may vary as other pulleys come into play etc etc. so far so good, and it definitely has more power and pulls nicely!
The Napa belt is actually shorter than 2000 mm and fit perfectly with some muscle to get it on.
The GL used to lag quite a bit going up hills, over bridges or when pulling a trailer…. Now it pulls like it is meant to. Lots of torque and steady power.
Will replace the unit in the spring when it is not raining daily here and check all the other pulleys and parts.
this is meant to be temporary, but, if it has worked for someone else for a year, it could work for yourself… again, your results may vary.
Last edited by GL320_CDI; Jan 4, 2025 at 12:11 PM.
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