W124 Idler Arm issue ?
 

I have a front end gremlin that comes and goes in my '90 300E. I think it is idler arm related, but I'm not sure. You can start out driving the car in the morning and it is fine. You stop somewhere for coffee and it starts to act up. You park it for 1/2 day at work, and at lunchtime it is fine again. Might not act up for another two days. Then it comes back. Next day, fine again. Here are the symptoms that come and go, seemingly randomly, with the car:

• Railroad tracks (wanders left and right slightly with the grooves in the road) when wheels are straight, but when turning is stable as can be.
• Feels a little sluggish on turn in - like there is slop side to side.
• Sometimes makes a noise when turning hard left or right that sounds like you are turning a steel rod inside a tight, dry, rubber bushing.
• Seems better in colder temperatures, acts up more frequently when warmer outside, or on the tail end of a long drive (hour or more away)

Ball joints, tie rods, both seem fine other than some weather cracking on the boots of the tie rod ends. They are still full of grease though. I'm going to replace the tie rods because of the cracking, but they don't seem to be the problem here.

Does this sound like an idler arm issue? Anyone know if there is a good DIY written anywhere for rebuilding the idler arm in a W124 ?

do a search... you don't rebuild it... you replace...very inexpensive part.

Tricky part is the nut and bolt. The bolt is restricted by the pre-cat.

I cut the head of my bolt off with a roto-zip and it fell out the bottom, then put the new bolt in upside down and put the nut on the top.

all of the repair gurus say its ok to do this.

Some owners seem to be able to get theirs out without cutting off the bolt head.

Still, a pretty straightforward simple job

No one seems to have the entire arm assy listed. Both MBShop and ******** list an "Idler Arm Repair Kit" (pic below) for like $20. That's where I came up with the "rebuild" term from.

[IMG]http://www.***************/secure/PartImages/1244600019.jpg[/IMG]

Do you agree with my asessment then Lee ? Sounds like an idler arm issue? I was just driving it a few mins ago and it was acting up again. This morning it was fine on the way in. I did notice that it is worse on highly crowned roads than on flatter roads. It also does not seem to be speed dependant.

that's it..... there is no need to replace the arm...you were right...it is just a kit...

it's the rubber bushings that are important.

Idler arm replacement solved a nasty shimmy on my W124 that i couldn't cure with new or rebalanced tires or alignments.

Indie charged me $50 incl. parts for the work.

It take 30 secs to check it.....get under there and see if you can lift it..if you can , it needs the kit.
..or , jack the car on one side and rock the tire l/r while watching the arm..if it lifts, it is bad.

Asking someone to diagnoses a front suspension problem to the 'T" by complaint does not get you a good diagnosis. A steering system is a tricky piece of geometircs and any weak link can cause the same problem as another..sao one must do an inspection of the components.

I just did the idle arm assy on my 1990 300D with also the drag link, steering damper, left and right tie rod assy. It cost about 150 in parts from ***************. Now I'm doing the rear. I purchased all the parts from the dealer at the tune of 700. Anyone have a time estimate on this job?

I realize that. I'm just looking to the more experienced MB folk to confirm that it SOUNDS like it could be the idler arm, or offer a more common failure to look at. Info like you included in the first paragraph above. (thanks BTW) I've been under there and looked at the tie rod ends and ball joints already - they all look and feel solid (other than the issue I eluded to with the boots being ozone cracked). I also checked out the wheel bearings, again, they seem fine. Plus, it being so intermittant is throwing me a curve.

I'm not mechanically inept by any stretch, but this is the first MB I have owned and I do not yet know MB's at all, so I tend to ask a LOT of questions on these type of boards.

At this age, bad idler bushings are likely - use the test Arthur Dalton indicated. Symptoms are similar to this part aging, except the noise. Noise more likely from ball joint or strut problem. Check looseness here with front jacked up til wheels clear, though may be hard to replicate sound without loading. Finally, have a pro drive with and listen for sound for confirmation.

Steve

<I'm just looking to the more experienced MB folk to confirm that it SOUNDS like it could be the idler arm,>

Ohhh. Now I see ..

Well, I am an experienced MB guy, and I don't think it sounds like an idler arm, but then again, I haven't heard it. and even if I did .I do not think I could diagnose a front end sound without poking around a little...so we are back to checking the components...
If you want some agreement that it is the idler arm, I would certainly do the simple idler arm test....and more poking around.
Groaning sounds from front ends can come from ANY component, as experience has schooled me. So ,I am certainly not going to condemn your idler arm from your detailed complaint. But I do offer the above advice..............

Thanks guys. Steve, the drivers side strut may be the culprit with the noise because it is the ONLY thing I can get to make any sound when turning with weight unloaded, and there is a distinct rub mark on the strut body. The rub mark strikes me as odd, because the rims are stock, the tires are the correct size, and they are properly inflated. Also, the alignment was just checked and was within specs. There should be no reason for them to contact the strut body. Also, the strut mount on that side looks brand new whereas the strut mount on the pass side looks old and cracked. I'm thinking there may be something up there that the PO "forgot" to mention.

You might want to jack up that side, pull the wheel, and post a pic here of what you see inside the wheel well - including the 'rub marks'. Perhaps someone will recognize whatever is not right. Worth a shot, anyway.

Steve

Bad ball joints squeal as well -- check for looseness. Bad struck mounts are obvious -- check for evidence of contact between the retainer bar on top and the shell of the mount. If there are cracks in the rubber, they are shot, replace them.

Ball joint can be done with the spring in place if you put a jack stand under the control arm and sit the car down on it. Press in and out with a standard cheap tool from Harbor freight, although you will need something to push on the ball joint with going out. They are directional, make sure the notch points toward the center of the car.

You may also have bad lower control arm bushings -- replace the control arm, it's cheaper and easier that swaging the bushings in. Requires a spring compressor.

Peter

OK, performed the test described above. The idler arm does ride up/down slightly. Not a lot at all, but slightly. I have the parts, so I'll rebuild it this weekend. I'm also putting new tie rods, intermediate rod, and steering stabilizer on.

Back to that strut for a moment though. sbourg said in an earlier post that "Noise more likely from ball joint or strut problem", and I do suspect that something happened over on that side (new strut mount on that side only, rub mark on the strut body that side only, noise coming from that area only..), so I wonder:

The ball joint is solid as a rock. I got to thinking...If the PO had someone work on that side, say to replace the ball joint, and they didn't properly jack or block up under the lower spring seat, could that have bent the strut and/or tore the strut mount on that side ?

Hi Andy,

As you go along with the job, could you document the steps possibly with pictures. I'm greatly interested in doing this DIY and would be happy for detailed instructions.

Thanks!