Recently the transmission in my 1998 C280 has been acting up. It seems like 75% of the time, the downshifts from 3rd to 2nd and 2nd to 1st have been pretty rough. It can get to the point where it will take 1-2 seconds to downshift, accompanied by a violent bucking of the whole car.

My question is this, I know these transmissions are prone to failure, but are these signs of the normal 722.6 failure? If so, can the 722.6 be rebuilt? Everyone I have heard of that has had a problem has had the transmission replaced entireley. Would'nt a rebuild save some money?

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I love my cars to death but my wallet sure doesn't.

Mercedes does offer rebuilt transmissions, they will take your unit and replace it with a rebuilt unit.

First, before you jump to the worst case scenario,

These transmissions are heavily integrated with electronics and computers, so having a dealership pull diagnostic codes may be the first thing to do.

Second when the car is up on the lift a quick look for any loose connections, leaks or even collapsed engine mounts or broken transmission mount plus broken flex disc.

Also a fluid and filter change done to see if it cures anything, is an idea.

Could even be a slight chance of MAF sensor n the air-intake causing the problem.

Good like with other replys and use the SEARCH

I had the fluid changed about 500 miles ago, and while it was in the shop I had them check for tranny codes, they said nothing came up. The problem didn't change, which makes me believe its a mechanical problem. Anyways, thanks for the reply.

__________________
I love my cars to death but my wallet sure doesn't.

Ask them if they checked the adaptation values for the trans. That's the way to tell if it's worn and in need of rebuild or replacement. If the adaptation vlaues are good, then you have another problem, probably the ETC and valve body which are notorious for causing the harsh downshift problem. You would be right to check the fuel trim adaptation values as well, as it's true that a going-south Air Mass Meter will also cause shifting problems.

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John Shellenberg
1998 C230 "Black Betty" 240K

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