"clunk" when letting of accelerator
 

Does anyone have any experience with a clunk type of noise when letting off of the accelerator? If I tap the accelerator, the noise happens when I let go. It kind of sounds as if the exhaust system is hitting something. I check the exhaust system for any play and it seems fine. Any ideas? andy

I've never had this happen before, but I'm inclined to think that it has something to do with the driveshaft. Maybe your flex discs or u-joints are going bad. Hopefully someone else will chime in and confirm this and give you a good method of tracking the problem down.

Alex

suggest that you
 

check your 1/2 shafts.

I think so that this noise come from the flex discs.
On my 240D the flex discs are worn and if I release very rapidly the clutch pedal (with the parking brake tighten), I can hear a metallic noise.

Mt 1985 300D does the same thing, and I have replaced the half shafts, flex discs, rear rtanny mount, motor mounts, center bearing and support, and yet the noise remains. I believe it to be in the ring gear and pinion in the differential. I have decided to live with it and accept it, as it isn't that bad. I recommend jacking your car up and having a guy hold one rear tire as you try to rotate the other back and forth to see how much play there is. I'm not sure how much is too much but you will possibly be able to duplicate the problem this way. another area might be the differential mount or even the rear tranny mount. good luck, isn't it fun to track down all these things? no ride is better than in Benz. thanks, adam:cool:

funny how you have this cluncking sound...my dad has a 300E and it just went to the repair shop today for a known cluncking sound. it was this thing called the differential disc or something like that....it is the ring right before the driveshaft extends out to the differential in the back of the car. that ring which supposedly holds in place the driveshaft was extremely loose and as a result....started clunking when the transmission downshifted automatically when slowing down. this caused the driveshaft to "wiggle" and make this cluncking sound under the car. maybe this might not be your problem since your experiencing this clunking every single time you let off the accelerator pedal. Just a good idea to get it replace soon as you can before other metal things rubbing against it might get damaged

I would have to say that it is your flex discs. I have looked at several cars that have made a clunk when letting off the accelerator, and have been told by a friend that is a symptom of a bad flex disc. Currently my car is making a clunking noise, but I think it is coming from the transmission. This post has reminded me to check the flex discs anyways.

Eric

Is the clunk from the front or back?

If its from the front and you have lowered your car its probably because you reduced the shock travel and then they bend the shafts. So you floor it, it comes down, and clunk.

If its from the rear, do what everyone has been saying. Check the flex discs, and half axles.

Austin

that is what i have yet to figure out - i have replaced both the half axles w/ dana reman ones and have also replaced the flex dicis front and rear. it drives incredibly smooth except for the occasional clunk on decel under the right conditions. any other ideas? to me it seems like the pinion staying spooled to the ring gear and then releasing which i guess is due to wear. i do only have 150 on it though, and the diff fluid has always been changed. thanks, adam b

The differential would whine if that was the case. I wouldnt think that your differential would do that yet.

I think its the shocks. Find where the noise is from.

Austin

I have also replaced the shocks front and rear with heavy duty bilsteins, the rubber diff hangar that is held up with 4 bolts is in great shape too, this is so odd, anyone else have this at all?

Check for ring and pinion slop. As a 4 wheeler I can tell you I have seen the sloppiest diffs make not a sound. My buddy's Ramcharger has so much slop he pulled out the rear driveshaft 'cause he's afraid it might fail but it doesn't make any noise. So, check that and see what's up. If it is the case, I'd say live with it unless it really bothers you. Ring and pinion gears usually last a very long time.

Frank.

Just my .02 but the diff mount could be a cause also. Mine is bad and clunks occasionally but hey it's part of the charm of the car.

Prop shaft
 

I used to come across a similar sounding problem with Toyota Hi Luxes and we traced the clunk to worn splines in the prop shaft. Pack it with grease and it disappears for a while. 2 solutions
1 buy a new prop shaft
2 live with it!!