My W124 is baffling me - PeachParts Mercedes-Benz Forum

McLoffs · #1 10-21-2002, 02:13 PM

Hello all. I have a problem with my W124 that's baffling me, even after consulting this group and a couple of different mechanics.

Basically, here's the problem. I have a 1993 300E with about 120,000 miles. The car is difficult to keep in a straight line at higher speeds. Also, there's a vibration under heavy braking (getting off the freeway, for example), and something just doesn't feel right about the suspension (it feels loose, mostly). Also, sometimes the steering feels wrong at low speeds -- like there's some sort of extra, "gritty" resistance. And a couple of times while creeping at low speeds (such as at a four-way stop) there's been a groaning noise from the front end. I've replaced the thrust arms and the steering dampener, figuring they'd help. They haven't really.

Over the past couple of weeks, I've taken the car to my mechanic and an alignment shop they recommend, figuring they'd be able to fix the problem. Based on the advice of this group, I had them look at ball joints, idler arm bushings, rear links, and bushings in general. The alignment shop checked all the suspension components, said everything was fine, and tweaked with the alignment. My mechanic lubricated bushings. The car felt better for a few days, but has reverted to its evil ways.

Does anyone have any more advice for me? This is getting really frustrating -- my Mercedes-Benz shouldn't drive like this. I'm about ready to take it to the dealer and hope they can find a problem, regardless of how expensive they'll be.

Thank you,
Mike McLaughlin

J.HIDALGO · #2 10-21-2002, 02:39 PM

Since your car "felt better for a few days". Something was done to affect the feeling of your car. Just go back and see what was done during the time when it felt better.i.e. alignment, lubricate bushings, etc. and then go from there. Good luck!

Mick J · #3 10-21-2002, 02:59 PM

Vibration under braking is most likely warped discs (you call them rotors on your side of the pond) but have the wheel balance checked first, front and rear.

Groaning from the front end as the car comes to a stop seems to quite common, if it at speeds below walking pace it is not the ABS as some people think as this cuts out below 5 mph. Both my 124s have done this, it may be worth replacing the front pads for original MB ones.

The straight line stability thing is not so easy to discuss. You seem to have checked everything although you have not said anything about tyres. Over or under inflation could cause this as well as uneven wear resulting from previous misalignment. Don't forget that these cars have old fashioned recirculating ball steering, unlike a modern rack-and-pinion system there should be some play in the steering and these means that minor course corrections as you drive along require larger movements of the wheel.

McLoffs · #4 10-21-2002, 03:14 PM

The alignment tweaking seemed to have a much greater effect than did the bushing lubrication; they were done a couple days apart. What does that tell us?

As for the tires, in the midst of all this I've replaced wheels/tires and it didn't seem to change anything. I am going to get the tires rotated and get everything balanced (hopefully this afternoon) and see if anything improves.

I had a feeling the rotors/discs were a problem. However, should it vibrate every time I brake? It doesn't, which makes me a bit suspicious.

Holson Adi · #5 10-21-2002, 03:56 PM

Quote:

Originally posted by McLoffs
.........I had a feeling the rotors/discs were a problem. However, should it vibrate every time I brake? It doesn't, which makes me a bit suspicious.

When I had to replace my front discs the brakes vibrated only when I braked from a high speed or whenever I used a lot of brake (going downhill for instance).

I replaced the discs and the problem was gone

I think it's time for the rears.. but I'll just do them when I replace all four pads.

chowpit · #6 10-21-2002, 09:01 PM

Next time the car is on the lift look at the front springs. The right front spring tends to bow out closer to the strut than the left does. If the bowing is significant enough this can give the car a "loose" wobbly feeling. I have seen the right spring almost touching the strut on some W124s.
If this proves to be your case, replacing the springs will be in order.
HTH

G-Benz · #7 10-22-2002, 10:16 AM

Also check the condition of the motor mounts. They could be shot at 120K...Mine are! It's amazing how much they contribute to front-end vibration...

joe p · #8 10-22-2002, 11:01 AM

Check the rear thrust links, these will cause the car to wander a bit and get a qualified Benz alignment guy to check it out.

Joe

McLoffs · #9 10-22-2002, 12:41 PM

The motor mounts were replaced a few months ago, and when I replaced the thrust links around the same time I figured it would cure the problem. Obviously not. :-) That does remind me, the mechanic did mention that another of the links in the rear could be causing the problem but they couldn't check it (they don't have a wheel lift, so they can't check the suspension under load), so he referred me to the alignment place. They didn't find anything, but are there other links that could be causing this?

md21722 · #10 10-22-2002, 02:01 PM

Where do you live? I wonder if you live in a Northern climate that is harder on suspension components?

Warped rotors will cause braking vibrations. You should be able to tell if its front or rear.

If the car is sensitive to wind, you may want to check shocks/struts. They can test okay bounce-wise but still be bad.

Does the back end seem to have a mind of its own and steer the car? Its possible that your subframe mounts are collapsed. They collapse internally. One check is to see how close the large metal washers are to the rubber itself. They should be apart! If it isn't, the mount has collapsed internally. Most shops know nothing about subframe bushings.

Right side spring will be closer to the strut on EVERY 124 car I've ever seen. Even if its a brand new spring.

The shop should be able to determine if a ball joint is bad. Its possible that your front lower control arm bushings are bad.

A lot of well-meaning mechanics will not correctly diagnose suspension problems. Especially possible if the car you're driving has spent any length of time in a climate where they're not from.

I would have another mechanic and/or alignment shop check it. I've been to MANY alignment shops that never said a word about worn components. In my case, the dealer shop foreman pronounced by front lower control arms as "shot" yet a very respected mechanic thought they were fine.

Brian

McLoffs · #11 10-22-2002, 02:38 PM

I'm in Seattle, and the car has spent its entire life here. I don't know if the Northwest is harder than normal on suspension components. Hopefully rain isn't a factor. :-)

I should have mentioned before that the shocks/struts are relatively new; within the past year. It sounds like I should have the lower control arm bushings and the rear subframe mounts checked.

Any suggestions where I should go in the Seattle area? Or can I do this myself (looks like the subframe mounts are easy to check; don't know about control arms).

md21722 · #12 10-22-2002, 02:54 PM

Mike,

I would get under your car and check out the rear subframe mounts yourself. There are four mounts that hold the subframe to the body of the car. Two in the rear go into the subframe from the bottom, the fronts go in from the top. Look for 4" metal washers. These should stick out from the mounts, away from the subfrrame. If they are recessed, then the mount is collapsed. IT may not be torn, or obviously damaged because it collapses from the inside.

For the front lower control arm bushings, I really have NO idea to how to check them. My well-meaning mechanic misdiagnosed it, the dealer alignment guy didn't catch it the first time, I took back the car for re-alignment and the foreman told me the bushings were shot.

The bushings are supposed to pressed into the control arms and never turn. The control arm moves on the eccentric bolts. If there is rust on the flanges of the bushings, the bushings are turning inside the control arm. This is one indication they need to be replaced, but not the only indicator.

Brian

McLoffs · #13 10-22-2002, 02:57 PM

Thanks for the information. I'll be crawling under the car tonight after work and will perhaps figure out what the problem is.

This is such a great resource -- I don't know how I'd maintain my M-B without it.

ILUVMILS · #14 10-22-2002, 07:28 PM

Hi McLoffs I've seen lower ball joints partially "seized" on more than one 124 in the past few years. It's usually only one side. The result is that more force is needed to turn the steering knuckle on the side with the bad ball joint. I know you said it was looked at already, but a check for looseness won't discover the problem because it's not loose, it's tight. This will give the car a very strange feeling under a variety of driving conditions. With the car on a lift, LOOK very carefully at the lower ball joints. Any sign of rust (usually a brownish color on the dust boot ) and that's it. The lubricant inside the sealed boot is long gone, and the ball is just grinding itself away. The extra effort required to turn the knuckle isn't usually noticed by the driver because the power steering can easily overcome it. Don't spend a dime until you have this checked! Good luck

McLoffs · #15 10-27-2002, 10:36 PM

I crawled around underneath the car, and it looks like the subframe bushings have seen better days. How difficult are they to replace? I'm leaning toward having my mechanic handle it, but if it's easy perhaps I'll tackle it.

I wasn't able to tell anything about the ball joints. I'm thinking about having them replaced when the car is in for the subframe bushings.

One observation -- I drove about 600 highway miles this weekend. At times, the car drove perfectly, and at other times it was doing all the things it's been doing. Any idea why it would vary?

Thanks,
Mike