Slow gear change on E250 W124

[dean36014]

Recently bought a '93 E250 multivalve, which I'm very happy with. However now i've had it a month I've noticed the gear change on the autobox is slow, mainly under hard acceleration. It seems to change out of gear, into neutral for a second or so, then change into the new gear. I've changed the fluid and filter, with no improvement. the fluid was a nice red colour, and no dirt or deris in the sump pan at all. I'm pretty convinced the fluid wasn't changed before purchase to hide a fault, as the bolts/gaskets didn't look like they've been touched in a long time. I used a Dexron 2 grade fliud by Comma? I've also done the torque converter test as read about elsewhere, and the revs don't go above 1800rpm. There is no slip on take off whatsoever.
The vehicle vin starts WDB124126, and according to the russian site I have a 722434 type box. Is there any common problems with these, any vacumn pipes to check etc.
Cheers,Dean

 

[grober]

Might be a problem with your control pressure cable adjustment ??

 

[bolide]

The typical faults on these boxes are hard shifts or excessive flaring, particularly 3rd - 4th. I've driven a couple that gave phantom shifts but walked away and don't know what the fix is

The box is controlled by vacuum pressures in a number of lines either side of the engine with a couple of connections under the crosspipe of the inlet manifold. When the pipe connections come adrift typically the box shifts hard. I'd take it to an auto transmission specialist that knows the boxes and ask them to pressure test it and, if possible, check the vacuum in the control lines. The figures will be in the Mercedes manual

If the fault is just flaring between 3rd & 4th under hard acceleration (when the revs drop slowly and the transmission slips for a couple of seconds) I wouldn't worry too much. It's common. I'm sure it could be adjusted out but you'll soon start driving round the problem. If it's doing real phantom shifts where it appears to select a gear, gets nowhere and tries again, I'd say you have a fault

Nick Froome
www.w124.co.uk

 

[Dieselman]

As Bolide says loss of vacuum will cause hard shifts as the vacuum acts on the external shift softener.
The actual workings of the box are by the governor inside the box with an input from the throttle pressure cable to raise or lower the shift points depending on throttle position.

Try disconnecting the vacuum, the box will work as normal but shifts will be harder.

This will tell you if the actual box is Ok, in which case just adjust the vacuum element to bring the shifts in right but with enough bite under full load.
It could be that someone has adjusted the vacuum element to be too slushy.

If this doesn't work it probably wants the brake bands adjusting.