W140 600SEC transmission woes. Ideas, anyone?

[growlygrowler]

Folks

I'd like to pick your collective brains if I may.

The gearbox (4-apeed auto, hydraulic box) in the '93 600SEC changes smoothly enough throughout the gears, but it doesn't seem to want to change up into 4th without encouragement.

By "encouragement" I mean taking my foot off the gas, dropping it into neutral, putting it back into drive and putting my foot back on the gas. Under these circumstances the revs then go up a little and then down as the box shifts up into 4th. There are no issues with changing down.

The fluid and filter have been changes with no effect and the oil level is OK.

Ideas as to what to try next, anyone?

Thanks

Dave

 

[ched999uk]

I'm no merc expert but the usual response is check vacuum pipes for leaks and check the throttle cable adjustments.

 

[jaymanek]

It doesnt sound great if you have tried a fluid change with no success.. I would contact a transmission specialist.

I see you are in Notts, if you can go as far as VMTP in cannock, I would recommend it.

 

[growlygrowler]

It doesnt sound great if you have tried a fluid change with no success.. I would contact a transmission specialist.

I see you are in Notts, if you can go as far as VMTP in cannock, I would recommend it.

Thanks. I think there's a transmission specialist fairly close by. I'll check out the vacuum pipes and any cabling first, though.

I'll also fire up the W140 DVDROM and see what I can find on there. I couldn't read any codes, but my Chinese copy of STAR seems to emulate the old HHT and there didn't seem an obvious way of reading transmission codes. If it's just a bad "signal" from a vacuum pipe or a faulty of blocked spring in the valveblock - and with the hydraulic box - it probably wouldn't read much.

cheers

D

 

[grober]

Check for stuck kickdown solenoid or for constant voltage to solenoid
caused by a defective fuel pump relay or sticking kickdown switch. Otherwise its probably internal as has been suggested. Get the gearbox specialist to check the hydraulic operating pressures are within spec as a starter.

 

[growlygrowler]

Check for stuck kickdown solenoid or for constant voltage to solenoid
caused by a defective fuel pump relay or sticking kickdown switch. Otherwise its probably internal as has been suggested. Get the gearbox specialist to check the hydraulic operating pressures are within spec as a starter.

Thanks, I'll do that.