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Intermittent thumping noise from rear when accelerating from a stop

6K views 14 replies 10 participants last post by  liviu165 
#1 ·
New to me 1990 300 SE has developed an intermittent thunk/thumping noise from the rear end when accelerating normally from a stop. Flex discs look good, as does the center support. However, there is a scoring mark on the driveshaft made by the rubber vibration damper on the exhaust shield. I am in the process of replacing the rear flex disc, transmission mount, and one engine mount. The front flex disc and a motor mount were replaced recently by previous owner.

While the car is up in the air, is there anything else I should inspect or replace to solve the issue?

Thanks,
Joel
 
#13 ·
Do you mean the centering bushing where the propshaft goes onto the trans and rear end, or the splines in the middle near the universal joint? The lock nut on the splined section should be tight enough the splines can not slide.

On my car a bad u joint caused a thumping noise.

-J
 
#8 ·
center carrier should be replaced when doing flex disks while you are there, inspecting for 50 cent repairs and replace with proper MB OEM stuff. Check anything that moves in the drive train. I would do the engine mounts in pairs and tranny mount as you said. Pay up for MB rubber bits where possible. Inspect bushings on shift linkage, they fail often but not related to issue likely. (rubber hangers for exhaust system don't last forever)
 
#10 ·
Great advice from everyone. Thank you.

I replaced the transmission mount and rear flex disc over the weekend. As far as the center bearing and carrier, I was too lazy to drop the exhaust. I will replace the old motor mount and then drive the car to see if there has been any improvement. Based on the how much the old transmission mount had deteriorated (~10 mm lower), I think this could have been the main culprit.

Joel
 
#14 ·
Check that your muffler isn't moving around and bumping something.
 
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