thump thump thump wont go away no matter what... 1985 190E - PeachParts Mercedes-Benz Forum

xp190 · #1 05-23-2003, 04:31 PM

I'm still struggling with the thumping noise I hear coming from the back while driving. I have no idea what it could be at this point.

The car is a 85 190E with 270000Km on it.

This thumping noise started during winter shortly after I had my flex discs and support bearing replaced.

Since the noise became noticable, I have dis-assembled and reassembled the drieshaft countless times. I replaced one of the calipers, both of the rotors, the differential, the rear flex disc again (since another came with the new differential), the wheels, and one of the halfshafts, I plan on doing the next one this coming week.

Nothing has changed, the thump is still there, it's related to the speed of the car, not the rpm of the engine, and becomes most noticable at 50-70 kmph.

I spent countless hours under the car looking around to see if something is wearing out, nothing...

I readjusted the hand brake, checked the bearings, all seem fine, yet the thump comes back after every single attempt of eliminating it.

The only things I have left are the rear wheel bearings, which won't be it since bearings make a whinning noise, not thumping, the remaining half shaft and caliper, and then I would have to start replacing parts that were already replaced in the past six months.

This situation seems really hopeless, there is no vibrations associated with the thump, it's just plain annoying and freaks me out that at any minute something could snap and put my car out of comission, and this is not good because I have to drive on the highway to work at least twice a week.

If anyone knows anything about this, please Help.... I'm running our of ideas.

xp

MTI · #2 05-23-2003, 04:34 PM

Can I assume that you've had the tires inspected? A failing tire will cause a bump, which will increase in a radial belted tire before the belt separates from the casing.

xp190 · #3 05-23-2003, 05:00 PM

I tried two sets of tires, nothing changed....

xp

ricali · #4 05-23-2003, 06:31 PM

Have you tried jacking up the car with both wheels off the ground and doing a test run ?? You may have something out of round. Just be careful to let it get away.

xp190 · #5 05-23-2003, 07:26 PM

tried that too, you can't hear it on the outside, seems that it travels along the entire drivetrain which makes locating it impossible. I might try that again, but it is a bit tricky to do on a driveway especially when the wheels have to be spinning at 50km/h and someone is to listen in to the noise, but thanx for the suggestion.

xp

blackmercedes · #6 05-23-2003, 08:22 PM

One of the prop shaft components might be out of whack?

ricali · #7 05-23-2003, 08:41 PM

Another thought my BMW had a similar noise and it was the exhaust hitting??

xp190 · #8 05-24-2003, 08:39 AM

It won't be the exhaust, it's clearly something that is revolving since you can hear it with every revolution and it is directly proportional to the speed of the car.

Other then the remaining half shaft, can anything else be causing something like this? Has anyone ever seen a problem like that?

xp

ILUVMILS · #9 05-24-2003, 09:28 AM

Sometimes the wrong flex disc bolts are installed. Make sure the ends of the bolts aren't hitting anything.

xp190 · #10 05-24-2003, 09:41 AM

that was a problem, but I correccted it a while ago, the flex discs were also installed incorrectly, fortunately I corrected that problem also, but it's still thumping....

xp

haasman · #11 05-24-2003, 04:00 PM

I just eliminated a thumping from the right-rear of the 190e. The sounds transmitted well through the body of the car and knowing the shock top was mounted abpve and below with rubber I didn't think it was that.

What was odd is it appeared only a certain spees (medium) not slow and not hight speed. Some bumps affected it .... others not.

I was prepared to have to do some serious repairs: links, bearings, mounts etc etc etc ....

...... turned out to be a "slightly" loose bolt at the bottom of the shock in the suspension arm!

Haasman

xp190 · #12 05-24-2003, 04:06 PM

thanx hassman, but I don't see how this would be the problem in my case, but I will check it out for sure.

Would you say that there was some sort of vibration associated with the thumping you had? Mine does not produce any vibrations at all.

xp

ricali · #13 05-24-2003, 04:44 PM

Noises are funny and can sometimes transmit from front to rear. If you eliminated things like brake pads hitting and flex shafts. Is it possible to have someone drive and lay on the floor to try and isolate where??

haasman · #14 05-24-2003, 06:04 PM

xp

No vibration what so ever. Strange really. At first, I went to the trunk to see what was knocking the metal on the side. Nothing.

It seemed to come and go. Then it started getting worse, regulary.

I was very surprised it was the bottom of the shock. I pulled both wheels and pulled and pushed everything. The clunk was well pronounced and continued to get worse increasingly. I finally pushed the rear fender up and down rapidly and that also made the noise.

Keep us posted,

Haasman

timreid · #15 05-24-2003, 10:48 PM

A friend had a thump noise which seem related to rpm, I drove and he rode in the trunk, it was a rear shock. Try riding in the trunk.
timreid