Floobydust

The transmission in my 2000 R129 as been occasionally shifting hard and sometimes missing shifts for a few months now. But yesterday, I was engaged in some spirited driving and when I took a hard right hand turn the transmission appeared to go into neutral (the engine then suddenly rev’ed). I stopped (I had not choice) and found I have not forward gears or reverse. I stopped and re-started the engine and still no go. I stopped the engine and waited about 20 minutes and then things seemed to be back to normal – all gears and shifting seemed normal.

My suspicion is that the trans is low on fluid and hard cornering causes the low fluid to shift to one side causing the hydraulic pump to cavitate and suck air. When that happens the transmission cannot hold any gears. Later in the day I tested this theory on a hard corner and while I did not get a complete loss of gearing, I did get hard mis-shifts (I believe the ECU goes into “high pressure mode” and raises the pump pressure when it detects low pressure problems and this causes very hard shifts).

Adding/changing the transmission fluid seems to be an area of big controversy. MB says don’t touch and even seals the fluid level check point. Others have changes the fluid in theirs. Should I just have it changed (I’m afraid MB will cry foul) or should I get out that jar of Vasoline and my wallet and go see the dealer?

Any thoughts or suggestions would be appreciated.

Thanks,

- FD

mebeJOE

Hey, this reminds me that this same thing happened to me once -- I had just about forgotten. Except I turned the engine off and back on and then all was okay.

That was at least 5000 miles ago. No problems since then.

If you take it to a dealer shop around. On some things the prices vary widely. For example, Downtown Mercedes in Los Angeles charged me $460 for B service. It is only about $200 at House of Imports in Buena Park.

JDM

I'd get it checked. If the fluid is low, it has a leak that needs to be fixed anyway. It's an expensive trans, you don't want it to chew itself up. Be careful who you take it to though...some trans shops can be thieves. The dealer should be your safest bet against that, and also for the know how. We just did a 96(?) and it was 4000 bucks. A sprag gear failed, and there was metal in the fluid, on the distick.(special tool, as car didn't have one either) Similar symptom with the irratic hard shift, then okay for a bit with key cycle.

JDM

https://mbworld.org/forums/showthrea...=sl+shop+trans

Floobydust

Thank you everyone for your suggestions. I finally sucked it up and went to the dealer. It turned out to indeed be low transmission fluid due to a leak at the point where the electronic controller connects to the transmission housing. It required simply tightening the attachment and a refill with trans fuild (using the MB secret, magic, proprietary transmission dipstick which does not come with the car, but is only available at the dealer) and I was on my way.

Dodged the bullet on that one. . . .

Thanks again,

- FD