Yesterday I had a very strange occurance with my 2000 XJR. I went around a roundabout pretty aggresively into another tight turn at speed (so I was getting a lot of body roll and side to side sloshing of fluids and everything) and then accelerated hard onto a straight, with the transmission in sport mode. Some cars were slowing up ahead, so I let off hard. The transmission seemed to hang a little and then when it finally downshifted it dropped the gear HARD, hard enough to squawk the rear tires at around 55 mph. The squawk was very short and then it went into neutral with the car still rolling and the gear selector still in drive. Tried shifting to 4th. No change. Tried shifting to neutral and then back to drive. No change. I figured I'd either blown up the trans or the driveshaft had let go, so I pulled off and put it in to park. I figured i should go ahead and try it before looking underneath, so I put it in reverse to see if the driveshaft was still there. Went into reverse like nothing had ever happened. Tried drive. Worked like a charm, no problems. Drove it home. No issues, even when I jumped on it hard. I am very confused. All I can figure is it got confused by all the jockeying I was doing just prior to the incident, tried to drop too many gears, sensed a high load situation from the sudden deceleration trying to spin everything backwards, and dropped it in neutral to save the trans. Anybody ever heard of such a thing before? Should I be worried about the trans, or is this a fluke?

 

I've heard a similar issue with the trans on an XKR - turned out a trans service sorted it right out. How many miles on yours?

 

Just rolled over 64,000 this morning. I thought the service interval on the MB box was supposed to be really long, but I guess I might go ahead and get a flush and fill for peace of mind.

 

Also of note: There were no error codes, yellow, red or otherwise. No gearbox fault message, no anything. Just no gearbox engagement until I put it back into park.

 

i had a problem simular under hard acceleration looking at the speedo like a child then had to slam on the brakes locked up the wheels and the gearbox woulnt engage even though in drive . All of a sudden all was normal

 

Well, now at about 500 miles since the incident, and nothing out of the ordinary to report. I think it was just a fluke, where the transmission got confused and threw the box into neutral to prevent any potential damage. Time will tell, but I've done several moves similar to what caused the problem before, and have not had anything even close to that happen again, so here's hoping it was a one time thing.

 

I'd still have it serviced. I think Mercedes has recommended a 60k mile service interval for that box since 2004. In 2000 it was still advertised as "sealed for life"...