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When I took my 2011 GL350 in for a warranty service a few weeks ago, the techs noted that the V-Belt needed to be replaced. I have about 60,000 miles on the truck.
I did the replacement today. It took about 15 minutes. A new V-belt (aka Serpentine Belt) costs about $30 on line. The Mercedes part number for the GL 350 Diesel Serpentine Belt is 0029934296. The actual OEM part is made by Continental - the belt itself is not Mercedes branded, but it comes in a Mercedes wrapper.
To do the replacement, first you need to remove the plastic engine cover.
Then you need to disconnect the air intake hose - there are two small star bolts connecting it to the engine, and one small torx screw connecting it to the metal air inlet.
Then use a breaker bar with an appropriate socket to twist the belt tensioner on the front of the engine, which loosens the belt so you can remove it. You need a 12 sided socket to fit over the protrusion on the tensioner - my 6-sided sockets did not fit. Note - do not remove the center bolt on the tensioner by accident - the thing you want to twist on is an obvious larger protrusion toward the bottom of the tensioner. If you have never done this before, spend two minutes watching a video on youtube - search for Mercedes replace belt - and you will get the idea immediately.
In the picture below, part #2 is the tensioner - you can see the protrustion you need to twist at the bottom of it.
Apply pressure counter clockwise on the protrusion on the tensioner, and this twists around the tensioner and thusly loosens the belt. Stick a nail or small screwdriver through the obvious retention hole in the right side of the tensioner to get it to stay in place in the "belt loose" position.
Before you remove the old belt, I suggest taking a picture or making a diagram of the route it takes.
The old belt removes easily. While you have the belt off, inspect the pulleys and the tensioner and look for wear, and replace as needed. Mine showed zero wear.
Installing the new one is simply the opposite of the directions above. No drama at all on this fix.
15 minutes and no special tools needed.
I inspected the old belt - and it looked in perfectly fine shape to me - no cracking or fraying anywhere that I could see - so this may have been the dealership trying to get extra fees, or just something they recommend at 60k miles as a matter of course. It was so cheap and easy to replace, I don't have a lot of heartburn over the DIY, particularly as being stuck somewhere with the Airstream in tow due to a broken belt is not my idea of big fun...
When I took my 2011 GL350 in for a warranty service a few weeks ago, the techs noted that the V-Belt needed to be replaced. I have about 60,000 miles on the truck.
I did the replacement today. It took about 15 minutes. A new V-belt (aka Serpentine Belt) costs about $30 on line. The Mercedes part number for the GL 350 Diesel Serpentine Belt is 0029934296. The actual OEM part is made by Continental - the belt itself is not Mercedes branded, but it comes in a Mercedes wrapper.
To do the replacement, first you need to remove the plastic engine cover.
Then you need to disconnect the air intake hose - there are two small star bolts connecting it to the engine, and one small torx screw connecting it to the metal air inlet.
Then use a breaker bar with an appropriate socket to twist the belt tensioner on the front of the engine, which loosens the belt so you can remove it. You need a 12 sided socket to fit over the protrusion on the tensioner - my 6-sided sockets did not fit. Note - do not remove the center bolt on the tensioner by accident - the thing you want to twist on is an obvious larger protrusion toward the bottom of the tensioner. If you have never done this before, spend two minutes watching a video on youtube - search for Mercedes replace belt - and you will get the idea immediately.
In the picture below, part #2 is the tensioner - you can see the protrustion you need to twist at the bottom of it.
Apply pressure counter clockwise on the protrusion on the tensioner, and this twists around the tensioner and thusly loosens the belt. Stick a nail or small screwdriver through the obvious retention hole in the right side of the tensioner to get it to stay in place in the "belt loose" position.
Before you remove the old belt, I suggest taking a picture or making a diagram of the route it takes.
The old belt removes easily. While you have the belt off, inspect the pulleys and the tensioner and look for wear, and replace as needed. Mine showed zero wear.
Installing the new one is simply the opposite of the directions above. No drama at all on this fix.
15 minutes and no special tools needed.
I inspected the old belt - and it looked in perfectly fine shape to me - no cracking or fraying anywhere that I could see - so this may have been the dealership trying to get extra fees, or just something they recommend at 60k miles as a matter of course. It was so cheap and easy to replace, I don't have a lot of heartburn over the DIY, particularly as being stuck somewhere with the Airstream in tow due to a broken belt is not my idea of big fun...
Thanks for the write-up. I'm thinking about replacing the alternator. Did you see it when you removed the V-belt?
Thanks!
The alternator on a GL320/350 is on the passenger side bottom. On the above diagram it is the small tight loop on the bottom left.
My alternator went out on my 2011 at 58k miles surprisingly. Did a OEM rebuilt replacement. Most of my other MB alternators last well over 200k if not beyond (my e300 just turned 300k on its orignal).
Something to keep in mind--the pulleys themselves are also prone to failure. My wife's '11 GL450 had a pulley failure (it froze up, so the belt was being dragged over a stationary pulley) at 75K miles that ate the belt. (We bought the truck with ~35K miles on it and never changed the belt, so it may well have been the original belt.) So, while replacing the belt, it may be a good idea to replace the pulleys as well. Ours had its failure four hours from home in the dead of winter, so I paid a mechanic to do the repair.
I have an '07 GL450 and just got the rebuilt alternator yesterday night. Trying to see if I have the courage to do this myself or outsource...
I'm a bit confused on how to release the Poly V-Belt, since it has this large coolant hose on top of it. I'm not sure if I'm supposed to remove that hose pipe or not.
I apologize for bringing up this old thread. I had a similar issue with my vehicle recently; I had a visible crack in my serpentine belt. I get a proper tool for the DIY then follow certain procedure on how to replace it. I came across an in-depth article that may be worth reading.Search for "Mercedes-Benz Serpentine Belt Replacement Guide on YOUCANIC" and you will see an article that goes over common causes and possible fixes. You can read about it yourself. I hope this information can assist someone else with a similar issue.
03-26-2016, 09:30 PM
