Mercedes-Benz Forum banner

4matic light help- shudder noise in reverse

1K views 3 replies 2 participants last post by  sach 
#1 ·
I have a 1992 300e 4matic, the 4matic light flickered and is now on constantly. when i put the car in reverse and cut the wheel i hear a thump thump or shuddering noise. car drives fine in drive. can i drive it like this. manual says to turn the 4matic lever in the engine compartment to the test position. What could the shuddering noise be when in reverse turning ? Any help much appreciated. this is my first mercedes... is this going to cost me a fortune. could it be the transfer case.

[:0]
 
#2 ·
Classical symtom for bad hydraulic feeder pressure.

"car drives fine in drive. can i drive it like this. manual says to turn the 4matic lever in the engine compartment to the test position."

You can, but it would be wise to check if the hydraulic oil reservoir and transfer case sump ATF are at correct level. Keep it in test mode until this has been checked.

"What could the shuddering noise be when in reverse turning ?"

The 50/50 center differential lock, most likely. Most often this is caused by infrequent hydraulic oil changes, and not using original OE oil. The brass bearings go zulu. Then hydraulic oil escapes into the transfer case sump.

If the brass disintegration is severe, you might also be hearing the center differential bearings crunch. Keeping it in test mode will prevent them from turning. If your transfer case is original, I think you may have steel bearings instead of brass.

Get someone with know-how to go over it. Because a detail like a defective flex disc, for example, might give similar symtoms. But the 4-Matic light shining is not a good indication.
 

Attachments

#3 ·
Thanks for your detailed response, i took it to my MBenz mechanic today, waiting to hear... left in test mode, looked under the rear end and saw hydrolic fluid leaking on both sides of the axle. maybe just a fluid leak and hence the noise due top low fluid level? or maybe as you indicate. i hope I didn't cause any damage. i took it right in. hope this doesn't cost a fortune...[:0]i will keep you posted. thanks Again.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top