thump thump thump wont go away no matter what... 1985 190E - Page 6 - PeachParts Mercedes-Benz Forum

haasman · #76 06-12-2003, 10:55 AM

xp

I can't wait to hear what they find! Imagine their surprise to find aliens or ....

Done transmission lines and it is an easy job. The fluid wants to drip all over. Also, since they are a supply to the transmission make sure everything stays as clean as possible. Years ago I had a 280SE that broke a belt and in the process the broken belt pulled off one of the transmission cooling lines. I was shocked. But the replacement line came with metal wire wrapped around it to protect it from future events.

Keep us posted!

Haasman

md21722 · #77 06-12-2003, 11:17 AM

Two wrenches, one on the flexible line, one on the radiator so lots of force is not put on the radiator or line. Use liquid wrench if they are tight as well.

brookspw · #78 06-12-2003, 11:44 AM

You will find this in the last place you look.

:p

Maybe your stereo just needs to be turned up.

xp190 · #79 06-12-2003, 04:28 PM

imagine how much I'm looking forward to what they will say, I'm just worried that they won't tell me anything I didn't already know. The guy asked me to bring in a list of all the work that was done to try and fix the problem to make it easier for them. We'll see.

xp

xp190 · #80 06-18-2003, 07:38 AM

Yesterday I took my car to MB to get the thumping checked out. I took the car there real early so they get it done ASAP. I gave them a list of all parts that I replaced in order to fix the problem and I told them that I just want to know where it comes from.

About an hour after I got home from the Dealer, (car stayed there) I got a call and my representative gave me some feedback. I was told the exhaust is banging on the subframe, which I know, but it will only do that when you force it, it never hit the frame while driving, the next thing I was told is that my tires are worn out, this I also knew, and finally I was told that my control arm bushings, which just so happened arrived the same day so I can replace them, are seizing, but, this I also knew. So Richard, my representative, asked me if I can come in and do a road test, I agreed, and was down there in half hour. The mech that was fixing my car pulled out and we went for a ride around the dealer. At first, I could not hear the thumping myself for some reason, I asked that we close all the windows, and sure enough, there it was. He listened to it for a while, I'm not sure if he heard it, but my dad was with me too and he heard it, and I know I heard it very clear, however my mech didn't seem to belivable about it. We finished the ride and he suggested that I get the tires replaced ASAP and offered me a new set of rims (for sale of course), then he said that at this point there is not much that can be done and I should ride it out. I have been riding it out since December.

In conclusion, the results did not get me any closer to solving the problem then I was when I got to the dealer. I ended up paying $45 for a car wash, which was not so bad I guess, but I can wash the car myself and it will cost me a lot less.

Right now I'm off to my garage to get those bushings replaced. My dad made me a puller just like the one in the Service manaul out of a piece of pipe, a big bolt and some washers. I'm sure it will work just as well.

I'm also planning on getting new tires as soon as I have done the bushings, this way I can get an alignment done too.

I'll let you all know how it works out.

xp

md21722 · #81 06-18-2003, 08:05 AM

You've worn out a set of rear tires since December?

107inOZ · #82 06-18-2003, 08:50 AM

OK so you replaced all the moving components it could be.

So it has to be something that isn't supposed to be moving. The wind can do some funny things, like making sheets on the clothesline flap in a strong wind. Think of the buffeting noise in some cars when you open one window a little.

Does your car have moulded panels that fit over the lower parts of the doors and guards. I had a 500SE that had a loose panel, and it flapped all the time until I finally worked out what it was.

Earlier Haasman suggested flow through ventilation, and the little flaps in the trunk (the boot in Oz).

Have you tried driving with the trunk open a fraction - just enough to make sure it is not pressurizing and depressurizing through the flaps in a rhythm? What about getting the noise clearly audible, and then lower each window in turn a finger width?

Pick a windy day. Drive against the wind, and then the opposite direction. Does the noise still stay constant with road speed?

Could the wind be banging the exhaust against the floor?

Mudflaps flapping? Rubber protection strips along each side of the car that have come unglued in the centre?

xp190 · #83 06-18-2003, 06:43 PM

No my winter tires are all good, I'm not using them right now, they are nicely stuffed in my garage waiting for the next winter, these are my summer tires, or just tires I use all the time, the winter tires I got just as winter was coming to an end, but I still need something for non-winter driving, so I will be investing in a set next week.

I just replaced the worn out bushing on the spring link, it was a LOT of work, but thanx to my dad I managed to get it all done, I just have to check the alignment of the wheel now and it's all good.

I was right about pulling off the wheel carrier, it's not that big a job, took me maybe two hours to do it for the first time ever, and remeber, I'm no mechanic

My dad brought me some heavy duty nuts and bolts from his work and we put together a puller which worked extremenly well. This 18 year old bushings was fused to the wheel carrier and we got it out and put the new one in without much struggling, other then turning the allen key

I just finished putting everything back together about two hours ago, so the entire project, not counting the e-brake since it was already off, which is another reason I proceeded with the removal of the wheel carrier, took just about all day

it's 7pm now and I started at 7am, so around 10 hours, give or take a few. Come next Monday I will be doing the same on the other side and then I'll put the e-brake back on.

This new bushing should make the ride a lot nicer, less road noise and no travel when hitting bumps. It already got rid of a very annoying squeak I had since the beginning.

I really love this car, and now I know that if I want to replace the bearings, take off the wheel carrier, and take it to a shop, end of struggle

As for the noise, well, I guess I have no other choice but to ride it out. Maybe it was the bushing, maybe it is related to the wind, although from my reasoning I don't see how.

The search goes on everyone, Thank you all so much for the support, it really helped

Now to fix other smaller things, like leaky valve cover sleas, and bad transmission lines

xp

btw, what tires should I get? I think I'll go with michellin.

haasman · #84 06-18-2003, 08:56 PM

XP ..... hmmm seems inconclusive ...... sorry to hear the culprit has not been discovered.

Tires: Take a look at the Bridgstone RE950s ..... great tire.

Haasman

xp190 · #85 06-19-2003, 06:03 PM

yep inconclusive. I'll be getting new tires as soon as the other spring link bushing is replaced.

The first one was pure rust, there was not a drop of grease left in it. There is a lot less road noise now with just this one installed, and the car does not travel off course when I hit a pot hole.
Can't wait to do the other one, all the other bushings look brand new, maybe I'll do the front some day soon as well

xp

psfred · #86 06-19-2003, 10:43 PM

XP:

Double race ball bearings, like the ones in the rear hubs, can indeed make a thump -- this is what happened to my 76 Audi Fox wagon (on the front). A distinct, almost too low a frequency to hear thump related to road speed. In my case, turning left reduced it, so I looked at the right side. Sure enough, when rotating the right front wheel off the ground, there was some resistance every other revolution. Ended up having the local import shot get the bloody thing out, we never managed to move it. They had to heat the carrier and pack it with dry ice and use their biggest press, it was STUCK!

Check your rear wheel bearings -- you may find a resistance or distinct noise every other revolution (the bearings are traveling at half the shaft speed).

Peter

manny · #87 06-19-2003, 11:27 PM

I think we should give xp190 the Nobel Price.......for perseverence !

haasman · #88 06-20-2003, 10:37 PM

xp

I feel incomplete not hearing the latest chapter to the "thump thump thump" saga ....

What's up? No aliens in the trunk ....

Haasman

xp190 · #89 06-21-2003, 08:44 AM

psfred, the dealer told me the bearings are a bit noisy but they are fine, they don't look bad, they don't leak and they rotate very nicely if you ask me, of course there is no play in them at all either.

Now that I worked out a way to replace the bearings I might do it some time in the future, but as just about everyone who "heard" the thump thump, and said to ride it out, for now I will, but it does not mean that I will stop looking for where that noise is coming from. I might have to use a different approach to fix this problem.

Right now I have to concentrate on tires and bushings since with worn out bushings no shop will do an alignment on my car. This should all be completed by the end of next week, the parts are sitting in my room, rear end only for now, front end seems alright but I have to take a closer look, I'll probably do that when I replace the transmission lines next week also.

Manny thanks so much for the nomination

but I have to hand it to you guys as well for all the suggestions up to this point. After all this problem originated in December 2002, it is now June 2003 and the car is still in one piece so I guess I'm doing something right

Oh yes and very driveable

I just don't race with it yet he he he

I'll keep you all posted as what turns out after the new tires and alignment, although I think I can guess already what the results will be he he he

xp

#90 06-22-2003, 10:16 AM

I admire your perserverance in attempting to find this annoying thump. It sounds like you have tried every possible logical thing. By the time you fix it, you will have a much better car. That being said, maybe it's time to start thinking out of the box.

From your description of the sound, I really wonder if you would hear a thumping noise if it repeated at the same rate of tire revolution at 50-70mph. Maybe you could stick some duct tape on a tire (or something that you know will make a noise and test the car at speed.) Then you will know if the frequency of the noise matches tire rotation.

Let's Make some assumptions: First assume that your engine is rotating at 3000rpm at 70mph. Then if your final drive ratio is 3:1 then the tires are rotating at 1000rpm. A noise that repeats at 1000rpm will sound more like a whine than a distinct repeating thump. For a distinct thumping sound to be heard, the repitition frequency would have to be on the order of 20-25/sec. As a reference, think about the 60 cycle hum of ordinary house current. From this assumption, I doubt that the sound is tied to anything that rotates at tire/axle speed.

Here's another thought: Does your car have an electric fuel pump and is it located near the tank in the rear? How about a noisy fuel pump? I had that happen once on a 1986SL. It only made a repeating noise after high speed extended runs.

Or perhaps the gas tank vent is partially plugged so the tank itself is expanding and contracting--popping in and out--as the pump is sucking gas out of it. It would not make noise at lower speeds since the vent could keep up with the lower fuel flow. Check the vents or replace the cap.

Or the filter is plugged so the pump is working harder and making noise at speed. Possibly the vapor vent return line is from the engine compartment is plugged or disconnected.

Since your car doesn't have all of the computers and sensors of a newer model, you could simply remove the gas cap to test these ideas.

Others have mentioned that loose piece of trim could be rattling in the relative wind. That's a distinct possibility. Another idea worth revisiting is the exhaust pipe or muffler is bumping or flexing in the wind under the car. New hangers are cheap. Give them a try.

Another thought: Are you absolutely, positively sure that the sound emanates from the rear? Sound can telegraph from one part of a car to another through metal shafts, parts, hoses, etc. Maybe you're looking in the wrong place. That sound sensing device could really help pinpoint it.

Good luck!