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Old 02-10-2008, 05:26 PM
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bhatt bhatt is offline
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Join Date: Apr 2000
Location: Oakville, Ontario, Canada
Posts: 421
W140 rear suspension clunk.. driving me NUTS!

Hello all,

I have a '92 500SEL with approximately 145,000 miles on it. It had about 115,000 miles when I bought it 2 years ago.

The rear suspension clunks over big bumps. The ride is PERFECT and has never been hard/bouncy/etc. It's just that this annoying clunk comes from the rear.

When I bought the car, the tech (who has worked at MB for years and knows his stuff) said replacing hydraulic shocks was rare but he really thought mine were gone. He had a set that had only 5000 miles on them (long story, but another customer had MB replace shocks when that was not the problem, so my mechanic bought them cheap from the customer).

So we replaced both rear springs (one had broken), both rear hydraulic shocks, there was no lever connecting the hydraulic fill/dump valve so he replaced that part and adjusted the rear suspension. He also replaced a rear "control arm bushing" as he called it.

He thought one of the "bushings" (metal ball at the top of the shock) was a bit loose on the old shock. So he was sure that was the problem. I don't remember exactly, but I'm 99% sure the new shocks had bushings already on them so he in fact did install new bushings with the shocks.

Still clunked....

Took it to another top MB tech in the area for a 2nd opinion. He looked at everything quickly in the rear and said he didn't see any obvious problems. Everything "looked tight" according to him. When I test drove the car with him, he certainly heard it. His only idea was to replace the accumulators because they were old and rusty (original to the car) and he said everything else looked in great shape.

A few months later I finally replaced both rear accumulators and flushed/refilled the hydraulic system.

NO change in the clunk at all. The ride was perfect, same as before. Didn't change at all. But the clunk was still there.. ARGH!

The only way I can reduce the clunk is to lower the rear tire pressure. But it only improves the problem a bit, doesn't fix it.

Any ideas? I don't know what's left and this car is driving me crazy. I am actually considering getting rid of it just because I can't maintain my sanity while driving it (clunk clunk clunk.. I have actually started to swerve a bit when I drive, avoiding cracks and potholes in the road, just because the noise is driving me nuts!)

Yes, the Bose audio system helps a lot but I can still hear the clunk
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