What goes "clunk" when I shift into gear | W210 97 E300
 

Hey guys, I've had this nocie for a while and figured sometime I'd try to get down to it. When at a complete stop and I shift into a drive gear, i.e. reverse or drive I can hear clunk. The clunk slightly varies, sometimes it louder and sometimes softer or almost non-existent. I had recently replaced both engine mounts with no effect on the clunking. The rear flex disc looks ok.

Could it be the transmission mount, rear diff mounts or even the rear subframe mounts. All of these I do not have record of being replaced.

Yes, yes, yes and it could also be the front flex disc or lash in the differential itself too, though I'd think you would only see that if the car had 200+K miles on it. I'd start by looking at the front flex disc, and try and turn the driveshaft by hand to see how much play there is in the differential too.

Sounds like a start. My '97 E300 has 198k on her currently

It could be the diff then too...especially if the oil in it is original...do you happen to know if it was ever drained and replaced? Does it clunk if you let your foot off the accelerator and then step back down on it or only when shifting between N and gears?

I did my fluid at 120K and used M1 75/90 gear oil...so far so good on my diff. If you find the diff is good then I'd suggest you drain and replace the oil as PM.

PS - I recently purchased a tranny mount with the intention of replacing mine as PM but just haven't gotten to it yet though the part is cheap and the job isn't too bad so if the mount looks suspect, and after almost 200K miles it may, then I'd do that too.

Hard to say even with that. I changed my flex disc and the problem went away. Yet the disc never looked cracked.

I know the diff fluid was replaced when I bought it around 123k. Don't know if it was repalced again @ 168k when I had the tranny fluid replaced again

Only when shifting between gears. Especially first thing in the morning

sounds like flex disc to me. Maybe it isn't broken yet but when it is cold, it is harder now

I liek your rational.. Once of these I must take the plunge and just replace them. Are they a pain to R&R?

Inspect the differential mounts. My '87 300D had a similar problem when the mounts were toast.

Not the simplest thing on your back but not a pain either.

My '97 did the same thing and a new tranny mount worked wonders. Feels like a new car again!

It drove me nuts trying to find the problem, though. I checked and rechecked the flex discs and all the mounts. The tranny mount looked fine from what I could see from under lying under the car, but due to the position of it I couldn't tell until I got it on a lift that one side had completely collapsed. Cheap and easy fix once diagnosed.

Good luck!

Klaus

Sorry to bring up this old thread but you asked the OP if his car clunks when you let off the accelerator. Well my friends car does that but it shifts fine between gears. Only when I let off the accelerator it will clunk and when I step on it. Like there is play in the drive line. What would this be? His car is a 1997 E300 diesel and he just bought it. The cluster was changed at some point so we can't verify miles and no service records so anything being changed or replaced is unknown.

Anyone?

Check the engine mounts and transmission mount. Pop the hood and try pushing the engine side to side by hand. There should be very little movement. Rev the engine in neutral and watch the engine if it jumps.
https://www.youtube.com/watch?v=bUl2H1JLR8A