Tap tap tap in reverse - PeachParts Mercedes-Benz Forum

ggenovez · #1 03-27-2008, 05:09 PM

Anybody run into this?

It only happens after I've been driving for a while and everything has warmed up.

I'll put the car in park, switch off, run into a store or something and put it in reverse and start to back up and I hear a speed sensitive tap tap tap. stop. put it in drive, wait a second and it's gone.

Otherwise the tap continues.

Only happens in reverse, engine hot after stopping for several minutes.

Thx

Blue 72 250 · #2 03-29-2008, 12:42 PM

I don't know if I can be of much help on this one gg. I would verify the obvious - mounts new and tight? Have you been fiddling around down there lately? could be a loose clamp on the high pressure lines going to the radiator.

cth350 · #3 03-29-2008, 09:36 PM

Have you checked the connections that hold the rear sway bar in place? -CTH

ggenovez · #4 03-30-2008, 05:54 PM

I have a feeling its tranmission related since it goes away after I put it in D and right back in R.

Baltobenz · #5 03-30-2008, 10:44 PM

I just happened to be browsing through the starmotorsny.com website earlier today and came across this in their common items to check for section:

U-joints. These are non-serviceable. If a clanking from the rear is heard, especially in
reverse, replace with a re-manufactured driveshaft.
5. Rear axle. The 600’s and 6.9’s rarely give problems in this area except for the 6.9’s half shaft. The axle half-shaft bearings are prone to wear. A clicking noise will be heard in such a case. Replace with re-manufactured unit.

Tomguy · #6 03-30-2008, 11:00 PM

Could it possibly be the parking pawl? Check it out - see if your shifter jiggles with the clicking.

cth350 · #7 03-31-2008, 07:21 AM

While you're under the car looking at the drive shaft, check out the rear swaybar and the rubber bits holding down rear axle carrier. Under reverse, the loads are all, well, reversed. Things that are usually pushed are now pulled.

On the air suspension cars, there are a couple of neat tricks pulled with the rear end to make the brakes work correctly. Lucky you, it's not that stuff.

-CTH