thump thump thump wont go away no matter what... 1985 190E - Page 4 - PeachParts Mercedes-Benz Forum

xp190 · #46 06-05-2003, 07:42 PM

I'd like to thank everyone for giving me any ideas regarding this problem and how to fix it.

If I had the money, I'd pay everyone big bux for the ideas, but as it turns out, every time I put money in this problem it is money wasted, well not entirely, but for this particular problem it is.

Your support means a great deal to me, but just so you know, I won't get rid of the car just because of this, I'm to deep into it now

and I think you guys just as well as me all need some closure on this issue.

My next big step will be to replace the wheel bearings, and probably wheel flanges, as well as some bushings on the control arm. I have a plan worked out for this, and I plan to put it into motion in the next two weeks, might be delayed since I got an email that there is a problem with my parts order. In either case, I plan to take off the wheel carrier, take it to a shop, get all bearings and bushings pulled and new ones pressed, put it back together, and when I take it for a ride pray that this damn noise is decided to call it quits.

Thank you all so much.

Regards
xp

haasman · #47 06-05-2003, 07:53 PM

xp

I got to hand it to you, you are really hanging in there. There is nothing worse than trying to find something as elusive as this.

I had another question: You say the noise doesn't start until about 40 mph .... are you sure? I know but it made me wonder if it isn't in the rear but a support bearing for the drive shaft? Sometimes these don't start making noise until up at a road speed.

Hang in there! There will be much celebration when you find what the culprit is.

Haasman

xp190 · #48 06-05-2003, 11:36 PM

hassman, I did consider a defective bearing. This one was replaced at the same time that the new flex discs were put in, just a few days ago I took the driveshaft apart to see if maybe it's the bearing but there is no signs of anything like that, the bearing turns normally although I did notice that the seal on it is a bit crooked, but it holds very well, I had a defective bearing before this one, and I could clearly hear where the noise was originating from, this, unfortunately is not the same thing. I can get the bearing from a friendly parts supplier for a very low price of $14, so I might be swapping it also, even though I really see no problem with it.

In either case, the battle rages on, as soon as I clear up my order, and place another one, I'll make another attempt at figuring this out.

xp

tower · #49 06-06-2003, 12:32 AM

This may be alittle off the wall, but maybe you can issolate the noise to a location by its frequency.

Further explaination.

Your explaination of the noise is that something is striking something - I assume - once every revolution. So..measure your tire circumference so that you can figure out what the natural frequency of the tire rotation at 40mph. If your "thump" is at this frequency, it must be the tire to differencial. If its higher, it must be in the transmission to differencial area (I assume that the driveshafts turn more than once for every tire revolution as american cars do).

This may help isolate it to a region of the car.

Tower

#50 06-06-2003, 03:09 AM

xp,

I had a similar problem with my 260e which would make a thumping noise at the rear which progressed with speed. Had my mechanic look at all the rear suspension components, bearings, etc. Everything was ok but the noise was there. It turned out to be that my wheel bolts on one of my wheels were too long and were hitting something inside the brake assembly. At slow speed, the noise is negligable but as speed progressed, it started to thump loudly. The noise started only when I changed my tire rims and only affected the left rear wheel. I just ordered shorter bolts and the noise went away.

Hope you solve your problem soon.

Nikos

xp190 · #51 06-06-2003, 10:32 AM

Tower, that is a great suggestion, unfortunately I beat you to it

I figured out that the thumping is associated with the speed of the tires since the driveshaft spins about 3.5 times faster then the wheels, the ratio on the differential is 3.23, meaning that at highway speeds this noise would be almost constant, it is not, this is why I concluded that it is something between the tires and the differential. To be sure I want to put a mark on one of the tires and have someone look out the window and see if in fact I am correct about this, but it's a bit difficult to do that since everyone in my family is always busy with something

Nikos your suggestion is also great, I had this same problem develop one time when I dissassembled the wheels and breakes to see if there was any wear and tear visible. When I put the wheels back together, one of the lug bolts would hit the spring that holds the e-brake shoe down. That problem was solved quite quickly since I was familiar with the way the springs were put together. I was also considering taking the shoes off and going for a drive, but I was told that this is not a good idea since the ebrake shoes are quite difficult to put back on. The only thing I would worry about is that the hook that connects the brake line to the shoes would get caught and cause something to break, this is why I have not attempted this yet. Perhaps I can disconnect the e-bake line all together and remove the shoes. It might reveal something.

xp

mithra · #52 06-06-2003, 11:29 AM

sign in the wheel wells of any sort of scuff, scrub, or scrape mark?
On any of the suspension components? Shock tubes, etc.? On the tire tread or sidewalls?

sbourg · #53 06-06-2003, 05:16 PM

Xp, without reading all the posts, I don't know if this was mentioned, but a shock problem can cause a rhythmic noise at wheel rotation frequency. I have had a loose/ worn shock mount do this, and internal problems cause this as well. Slight normal wheel diameter/ balance variations cause the shock to knock about in this case. This is usually evident on inspection removing the shock, and a short drive with the offending shock off will confirm.

Steve

xp190 · #54 06-06-2003, 05:40 PM

I didn't know you can drive without a shock, but if I can, I will be more than happy to try this. I think I'll start removing everything piece by piece starting with the e-brake to see if it goes away or not. Sbourg, can you give me any more details on this? Should I watch for anything in particular? I imagine the car will be very bouncy without shocks.

To answer the other question, I have spent countless hours under the car looking for any sign of wear, scrach or scuff marks and have not found anything at all. Even though that is a bad sign, I wish I had found something like that.

xp

sbourg · #55 06-06-2003, 05:54 PM

First bounce the car up and down in the back and listen for a knocking noise from the shock area. If there, and you can localize to one side, remove that shock, carefully, and noting the condition of the bushes and mounting hardware for problems. With the shock removed, test it for freeplay going from bound to rebound - there should be none. If this isn't conclusive, take a drive up to the speed where you notice it, and see if it is still there. Note you are doing this with 3 shocks still on the car.

If the noise is still there, replace the shock, and perform the same operation on the other side.

Steve

xp190 · #56 06-06-2003, 06:07 PM

I'll try that steve, but since I have never done anything like this before, I'm a bit concerned about the spring. Is there anything left besides the shock that will hold it in place? If I remove the shock and raise the car, is it possible to take out the spring? Wouldn't this damage other components in any way? I am guessing I should keep the car on the ground at all times when it is without any of the shocks, is this correct?

xp

manny · #57 06-06-2003, 10:06 PM

xp 190

Is your girlfriend still with you ?

sbourg · #58 06-07-2003, 01:45 AM

It has been long enough since I replaced the rear shocks of our 190 that I don't remember the details. However, it did not involve removing the spring. Obviously, choose a venue which does not tax the suspension during the test drive.

Steve

haasman · #59 06-07-2003, 01:53 AM

xp

Shock replacement in a 190E couldn't be easier and the spring stays in the car and does not need to be compressed.

The top of the shock is accessed through the trunk by taking out the inside plastic liner, starting by the tail lights. Once exposed the shock top is held by two 17mm nuts. Hold the lower while the top one is removed. Then do the lower.

The bottom of the shock is access by first removing the plastic cover of the "A" arm (it really isn't an A arm) by removing the 10mm self-tapping bolts, three of them if I recall correctly.

Once exposed you will see a through bolt and a nut on the other side holding the lower shock end into the A-arm. BTW, this is where I got rid of the "clunking" sound in the 190E. As you will recall I chased this noise for several weeks. Once again, the bolt/nut were not particulary loose. I tightened them and the noise went away.

Haasman

xp190 · #60 06-07-2003, 10:22 AM

Thanx a lot hassman, first thing Monday morning I will try this, then if it does not help, off with the e-brake components until there is nothing left.

and umm no Manny, she's gone, damn underwear models....

xp