Hi,

I have a Merc V280. This vehicle is fitted VAG engine and auto box. The engine is a VR6 2.8 and the box a VAG 4 speed auto fuzzy logic box, same as is fitted to the 4 speed Sharan, so I'm hoping someone here can help me.

The auto box was slamming into gear when changing from 1st to 2nd. It would do this just over 50% of the time, but only when warm. I drove it as little as possible, just to garages to get it looked at, but during this time it stopped slamming gear so often to the point where it almost never does it now. The weather had become much colder and the oil had been topped up during this period so one or both of these things could be the reason.

Unfortunately, at the same time in the reduction in slamming the gear changes it seems to be slipping when changing up from 2nd to 3rd. It does this consitently and the slip goes on for exactly the same amount of time on each gear change. I thought that if the clutch plates or brake bands were slipping then how long it slipped for would depend on the power provided by the engine, the speed the vehicle was travelling, the load the vehicle was carrying, the incline of the road, etc.

I've not had an automatic before, but the slip is not like when you semi depress a manual clutch to slip it. What it seems like to me is...

o 2nd gear is disengaged

o the engine instantly revs up a bit, but not out of control, and remains at that set speed (about 3.5K from memory) for about a second - like it's in neautral, but with the revs limited.

o 3rd gear is engaged and the engine revs instantly drop to the right speed and full traction is gained.

Does anyone have any ideas as to what could cause this behaviour? Mercedes and a transmission speciallist both want to strip the box and just look inside it as they don't have a clue. Cheapest quote: £2330!

Thanks in advance for any help you can give!