what's causing this noise? 300e 1991 160,000 miles

Hi Guys,
This is very frustrating! I've taken the car to the shop twice and both times it stopped making the noise on the way. I was starting to think I was delusional but
my girlfriend was with me when it did it the other day. I don't have the best hearing anyway, but she hears everything.
It sounds like the exhaust system is bumping the bottom of the car, but it's not because I wiggled it and it doesn't hit the car.
It makes a clanking sound that has a frequecy and a variable volumn/intensity. It starts out loud and then as you drive away if gets softer and faster and you can't hear it at speed. The freqency is about two clacks per second and increases as the car goes faster to the point where I can't distinguish individual pulses of noise.
When decelerating it makes the noise, and gets louder as the speed comes down. It doesn't make it stopped at idle.
It doesn't make it stoped at idle in neutral revving the engine.
It does it for about 30 miles of driving, and then stops for a week or so. Each time it stoped, 3 times so far, I guessed whatever was causing it fell off, or something.
Any ideas what may be causing this?
Thanks,
a
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I'd suspect one or the other of the rear axles' spider joints aka constant velocity joints. You can superficially check these by crawling under the rear - from the rear - and looking up at the axle shafts between the differential and the wheels. Each axle has two rubber booted constant velocity joints, a torn or holed or (grease) leaking boot is the probable culprit as its internal joint is worn out (making THE noise) and must be replaced. Not a cheap fix.
These axles are available on a remanufactured exchange basis, see: http://www.cvjreman.com/MercedesBenz.html
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Thanks TG,
I think you may just have identified the problem for me!
Do you have any idea how many "careful" miles I can drive on it before I call a tow truck?
Thanks again,
a s
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Until the joint breaks, the axle falls onto the street and the car stops for lack of propulsion?
I'd say, by your description, that it's on "borrowed time" now and should be driven slowly, and only once - straight to the repair shop.
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Re: what's causing this noise? 300e 1991 160,000 miles
Until the joint breaks, the axle falls onto the street and the car stops for lack of propulsion? I'd say, by your description, that it's on "borrowed time" now and should be driven slowly, and only once - straight to the repair shop. XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
ah yes the days of yesteryear
i once had an 73 olds Tornado. the front drive axle started to click. a few weeks later it locked and i had the ride of my life at 20MPH. the front of the car hopped up & down once or twice foweled by big ball bearings rolling down the hill. and yes PARK doesn't work after they break!
loved that car. it would plow through snow better than a truck.
an added plus it had anti lock breaks in the rear. they hissed like a pissed off cat when activated.
case
the case, minus a few cans!
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ouch. that's what I was afraid of.
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Clearly you're being misled here!!!!. I was careful reading all of the posts regarding your problem. First off, no need to panic, you have a 1991 300E (124) car, None of your rear axles will drop to the street and leave you stranded. And you can take this to the bank, I have a Mercedes service and sales shop, I wouldn't just come out and undo what the other two advisers told you. Lets assume one of your rear axles is infact the problem, the noise will get worse, and still it wouldn't come apart, you might start to expersience heavy vibrations with the noise. You pull over, and take off again, he noise is gone, stayes gone for another 20 miles, that's how a Mercedes axles will make itself none. In the mean time, relax and wait for the noise to get worse, I'm not even convinced that you have an axle problem, I haven't changed 1 on a 124 car. Cheers. Autobahn Auto (757) 723-2112
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Cheers
Thanks for your thoughts Benzman. I finally got it on a lift yesterday and fond the bolts on the constant velocity coupler were loose on the driver's side. One of them was 1 1/4 turns loose, the rest were a quarter to 3 quarter turns loose. Passenger side was tight. It made the noise on the way to the shop, and didn't on the way back, so I'm hopeful. Examining the drive shaft ends, the one at the front that connects to the transmission had some play in it, not much, but I could see the bolts move before it started to turn the driveshaft. The mechanic said his guess was one of them was causing the noise. To be safe, I ordered the rubber part for the front and will install it over the weekend.
Thanks to everybody who took the time to help me with this.
as
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The flex disc is what I had in mind in the first place, but, usually there is vibration associated at take off?. Martin Autobahn Auto
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