I have this clunk that's coming from the rear end of my '85 300D. I replaced the sway bar links, checked for loose exhaust and so forth, but could'nt come up with anything. The clunk happens when the car downshifts and sometimes upshifts. I can also hear it when I'm in stop and go traffic and I'm tapping on the gas pedal. I took it to a local mercedes mechanic, he drove the car and thinks it could be the differential? Any ideas? At this point its more annoying then anything. Thanks

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2012 550CLS
1982 380SL
1985 300D
1998 ML-320
1997 E-320
1984 380SE

U-joints, flex discs and CV joints are all problems that would produce the sound you're hearing. If it happens when you're doing something with the pedal, it's most definitely in the drivetrain system somewhere. You'll have to poke around, or have your mechanic poke around, and have a look. I'm not sure about the diff., but I always thought that they were pretty hardy. Good luck. I've never had to personally replace any of these parts, but lots of people here have, so they're very doable (I think).

Alex

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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside

Sounds like flex disk to me....

Should be very easy for a mercedes savy mechanic to diagnois.


Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E

I agree....my exerience with this car is that while we often suspect the worse (i.e. bad differential) the actual problem often turns out to be relatively minor (flex discs). The differential on these cars will easily go half a million miles...probably even without fluid change...as long as fluid is topped off periodically. I would put my money on flex discs. Next most likely would be U-Joint or CV joints on axles. Least likely would be differential.

Good Luck,

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

check 1/2 shafts.
do a search there's a lot of info (i know...)

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

My 1982 300D has a loose / worn differential.

Pretty easy to diagnose. Park the car someplace where you can get under it far enough to turn the driveshaft by hand. Set the parking brake (use wheel chocks if necessary) and put the transmission in neutral.

Now reach under the car and rotate the driveshaft back and forth. If you can turn the driveshaft back and forth while the wheels are standing still, your differential is "loose". And while under the car you can make sure there is no slack in the half-axle shafts, because they probably won't be turning either.

I get about 60 degrees of a turn looseness. That's pretty bad I think, and it does the "clunk" in transition from acceleration to engine deceleration.

Ken 300D

Thanks everyone, I'll try to get at it this weekend post results.

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2012 550CLS
1982 380SL
1985 300D
1998 ML-320
1997 E-320
1984 380SE

Looked underneath today, everything seemed in order. In fact, the flex discs as well as driveshaft seem fairly new, no signs of wear. With the car on ramps and in neutral, the driveshaft would turn maybe a couple of degrees. I have a feeling it might be vacuum related, even though I have no vacuum issues. I guess I'll just throw in the towel and forgive a car with nearly 200K for making a little clunk.

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2012 550CLS
1982 380SL
1985 300D
1998 ML-320
1997 E-320
1984 380SE

Update, after reading some info on half shafts, I decided to play around with mine. The passenger side slides in and out, no play twisting it back and forth, and seems smooth and quiet. The drivers side slides in and out, no play twisting back and forth, however, when I'm sliding it in and out, it makes a noise similar to the clunking I'm hearing. Could this be the culprit? are the half shafts supposed to be silent when sliding them in and out? No tears in the boots or leaks. Thanks

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2012 550CLS
1982 380SL
1985 300D
1998 ML-320
1997 E-320
1984 380SE

Alan, I know this is off-topic, but where did you get your avatar? I'm an aero-nut

You probably have found the problem with that half-axle. Certainly the differential seems good.

It probably depends on the exact nature of the problem, but a lot of half-axle problems show up on tight, slow-speed turns. Kind of a whump, whump whump from the side opposite of the direction you turn (its moving faster under more stress).

The condition you describe may not actually cause you a problem for some time, but may well be an indication of some wear.

That's the best I can do for an Internet diagnosis!

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Thanks for the replies, I figure it can go for a long time like this for the clunk really is no big deal, just annoying. I'm happy that I think I finally figured out where its comming from.
Warden, as for the avatar, I'm a furloughed TWA pilot, or I guess its American now, anyway, I scanned a sticker that I have and made it fit. It took me a long time to figure out how to make it squeeze into such limited space, but the results aren't too bad.

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2012 550CLS
1982 380SL
1985 300D
1998 ML-320
1997 E-320
1984 380SE