bk_321

My C320 Coupe (manual) intermittently (once a week) goes from 1st gear back into neutral by it's self. This normally happens half way through an intersection and can give a violent bang noise/gear grind. I have even had it happen while I was holding the shift knob and could not stop it from going from 1st to neutral.

I took it to the dealer and they made a shifter link adjustment ($300), which did not fix the problem. Since they have not seen the problem they told me that they can't do anything else to fix the problem. Just bring it in when it happens.

Has anyone had this problem, or know what could be wrong?

nismo1028

i have the same problem with my c240 sport. problem wasnt constant at first but now is constant and cant even use first. i was told could be a bent shift fork or bad syncros!! im suppose to recieve a call back from the shop tomorrow

Boom vang

Bad synchos will not make a gear slip out, it will however make it hard to engage as it will cause grinding. Think of a synchro as a small brake (sort of a reverse drum brake in function) that slows down the rotation of the gear so that the dog gear can slide and engage on the next gear. Synchros are usually a brass or bronze ring that is slightly smaller on the interior surface which it is slowing down (similar in function how brakes work on a train wheel - they push in and against as they slide on a somewhat inclined surface or cone as it is called)

To me it sounds like 2 things, the tension in the shift mechanism; or a bad dog gear which could be caused by weak internal springs or worn ***** to hold the dog position as it slide and not hold in its latched position.

I am sure this sounds Greek to you. I've rebuilt a couple of Triumph sportscar gear boxes in my time and actually is quite simple once you understand the dynamics in how it works.

alpinweiss

You didn't specify the year model, so I will have to make a couple of assumptions. Mercedes had some issues with the 6 speed manual transmissions on the early W203 series, including jumping out of 1st. These transmissions had the "dog leg" reverse; in other words to engage reverse, pull to the left and back. Most dealers will not service this transmission, and will only replace it with a rebuilt unit. So you may have to go to an independent Mercedes specialist that is willing to work on a manual gearbox.

The later series 6 speed transmission (reverse gear to the left and forward) was supposed have cured this problem. I am not sure of the transition date from old-style transmission to new; I think around 2003?

johnnyboy_98

Definitely invest some time to figure this out.

I had this problem on my 2001 C240, happened about once a week or so, same symtoms, except mine was 2nd gear... Last week I lost 2nd gear completely, and now I'm looking at a major tranny repair.

I'll repost more info if I can find someone who'll tear into my tranny without it being a $3k repair bill... If I can't find someone who'll do it for $1500 or less, I'm parting the car out.

nismo1028

I found a local private service department (conway motors - specializing in mercedes, bmw, jaguar, land rover) who will remove, repair and reinstall the tranny for $1500-$2000 depending on parts. I'll know the problem when the get it apart. Local mercedes dealers wouldnt touch it.

Decide im going to put this thing up for sale when i get all the repairs taken care of (drivers door lock pogo, tranny issue!!, and sway bar links)
Early model C240 sports (2002) just have too many reaccuring problems.

nismo1028

well the problem wound up being the shift drum and first gear set... its back together now and picking it up tomorrow... anyone know of a buyer for a 2002c240 sport, white w/blk leather.