Rebuilding Idler Arm

The following VFAQ was created to help people replace their worn idler arm. As always remember the lovely legal disclaimer that I do not accept any liability for yours or anyone’s actions who may follow any of my guides.

What exactly is this thing and where is it? Well I never heard of this part before, I hear it is quite common on trucks. I suppose it makes sense, if the gearbox is supporting one side something has to support the other side, but what? An idler arm! What happens is when the rubber bushings get wear or aged they start making the car feel like a side to side swaying at slow speeds. This is caused by just that, the idler arm is allowing one wheel to move freely from side to side. You have to man-power the wheel quite a bit to see it move, but if and when it does move like that you know it is time to rebuild it.

This is a very simple and straightforward job, the hardest part is getting the old bushings out. I had the front wheel off, air cleaner out, and car supported a bit higher in the air since I was working on the rest of the front suspension at the same time. Take the huge bolt out, seems like it is about a 24mm head. Bolt came out without much effort, just let the tierods support it up and out of the way. Next a grabbed the rubber bushings with vice grips and moved it in a circular motion while prying against it with a flat head screwdriver. This got the rubber out but left the metal bushings inside. They were so close in the middle that it was hard to get one out so the other could come out. I ended up using the sharp edge of an extension against the one coming up, then from the top I used the mini-sledge with a 3' 3/8" extension & as large socket as I could use to fit in the hole. With enough effort it finally came loose.

There aren't any real tricks to reassembly here, just let the bolt pull it together after getting one side fairly close to being right. I purposely over torqued it then backed up a little bit to make sure everything was seated alright, it seems like the Mercedes specified torque is 80newton-meters (~62ft/lb).

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