jtalbert

I have had my C240 4Matic for 3 weeks now, just hit 70,000 miles and twice in the past two days, when I am accelerating from either a complete stop, or after I have started to accelerate more from 5-10 miles an hour, if I very slowly press on the accelerator, my car has a slight hesitation with the acceleration and as I give it more gas to accelerate, I have twice felt a strong vibration coming from the rear loud enough to make what I think may be my exhaust to rattle loudly, not sure if its the exhaust or not, but it sounds more of a rattle of something rubbing against something on the outside than an interior rattle, if that makes sense. Has anyone ever encountered this and if so what may be causing it?

mleskovar

Rear transmission mounts seem to go out a lot on these cars but check the whole drive train while you're under there.

jtalbert

An update. The issue happened again. I know I have experienced this before. It's like when your driving a manual car and you start off in 3rd gear and not 1st. It happened tonight as I was pulling into a parking lot. I felt the transmission shift and when stepping on the gas the acelleration was off. I just got this car three weeks ago and now not happy.

Carsy

Could be blocked Cat Convertor or muffler baffles loose ? Have someone push gently on the throttle whilst you listen at the exhaust pipe end . A loud hissing denotes a blockage. Also give the exhaust a shake with a rag or glove to see if it is loose. Don't burn yourself.

Glyn M Ruck

Check rear transmission mount, Cats for broken honeycomb (as said above), all exhaust hangers, make sure that a heat shield is not touching the propshaft, check flex discs on the propshaft, center propshaft bearing. Propshaft UJ, side shaft CV joints. (I have left out front propshaft & sideshaft CV joints because you are convinced that the problem is at the rear. Kardon had a similar problem - search for his thread)

Good luck!

jtalbert

I am not 100% sure where its starting from, I thought it may be the rear since it rattles the rear end.

QUOTE=Glyn M Ruck;4757966]Kardon had a similar problem - search for his thread)[/QUOTE]
Is this the link?

https://mbworld.org/forums/c-class-w...-50-70mph.html ?

My car drives fine at highway speeds, drove it 90 miles yesterday and very quiet at highway speeds. Took a nice 20 mile drive for lunch today with my mother-in-law and no problem either...

My problem only seems to happen usually as I accerate from a low speed, after I get to a higher speed it stops, and noticed a shift as I was pulling in a parking lot which sounded like it may have started the same problem, but I had to stop the car before I could accelerate to verify (ran out of pavement :-) )

I drove it a few times today and no problem its its very odd, its only happened twice over the past few days.

Glyn M Ruck

If I was to guess - I would say rear transmission mount has collapsed.

mleskovar

Isn't that what everyone does on internet diagnostics for intermittent problems?

Glyn M Ruck

Damn right Mark