E230 Auto Overrun thump when I brake - Any Ideas
 

Hi,
My pride and joy E230 Auto has only one problem. When I brake following a period of time on a straight road, the car seems to experience a thump like someone has bumped into my rear end. It seems to me as if the clutch orsomething isn't disengaging the drive on time.

Is this a common problem and can someone help me diagnose the problem.

Much obliged for any help.

RE: E230 Auto Overrun thump when I brake - Any Ideas
 

Hi,
Is this when you brake or go onto overrun i.e. just engine braking. Tryt repeatedly applying power and then off in a rythmic pattern a few times.

If the later it is likely the diff mountings especially the diff nose.
If the former then I suspect a suspension bushing is shot or loose.

I assume you have nothing loose in the boot / under rear floor. e.g. Battery?

Mileage?
Vehicle history?
Might help locate problem.

RE: E230 Auto Overrun thump when I brake - Any Ideas
 

Thanks that gives me something to discuss with my mechanic friend.

My car has 140,000 miles with a good service history and runs very well. I usually experience the problem when i've been on the motorway and come off an off ramp slowing to a stop with gentle braking. It can also happen in town when stopping at traffic lights.


I'm confident its not anything loose in the boot or bonnet.

RE: E230 Auto Overrun thump when I brake - Any Ideas
 

I should have clarifies that it occurs when the car is almost ata complete stop.

RE: E230 Auto Overrun thump when I brake - Any Ideas
 

Have a mechanic look at the drive shaft... my car has a clack noise just before to come at full stop..

RE: E230 Auto Overrun thump when I brake - Any Ideas
 

maybe the differential?

RE: E230 Auto Overrun thump when I brake - Any Ideas
 

My previous post stands but if the noise is in the centre of the car, just before coming to a stop and if it is a feint sort of clunk then this appears to be "normal" and a "feature" of the drivetrain. My 320 does it also. The original post suggested something much louder (....somebody bumped into the rear!!)
I do not actually know what makes this noise. I suspect that it is something in the gearbox.
I will find out since I am also interested unless of course somebody watching this thread already knows.
Stuart

RE: E230 Auto Overrun thump when I brake - Any Ideas
 

Ju8st to clarify further, there is no actual noise that can be heard whilst driving. The thump is a physical lurch forward with no perceptible noise. The explanation that it could be a delay in the gearbox changing down from 2 to 1 seems plausible to me.

Thanks for the ongoing interest.