kick down problem on 280E

[foursail53]

Hi folks - have a kick down problem on my 1973 280E 4-door saloon (petrol 2778 cc) Auto (obviously!) - (W114 chassis and W110 engine) - there I said it. The kick down tries to work but gives up and I don't get anywhere.

Oddly the engine appears to rev Ok in 'neutral'.

Any ideas about how I can diagnose this? Any ideas?

Many thanks from a new boy.

 

[pascal]

First check would have to be the switch itself

 

[flagstaff]

then oil level in g'box

 

[TimN]

Chances are that it's got someting to do with oil pressures in the gallery. Any idea when the filter and gear box oil was last changed?. There may also be a vacuum connection with the gear box. I'm no expert but the vacuum connection may be the only indication the gear box gest of the revs the engine is doing. Have a look down the back of the engine to see if there are any disconnected or perished hoses.

There gear box will not always engage kick down. It has to decide whther there is scope for kick down. It may be that it has come out of adjustment and thinks that it will over rev. Try kicking down at various speeds.

 

[TimN]

Whilst I remember you might find a cam on the oil pump drive shaft which somehow informs the vehicle of the engine speed rather than by vacuum.

 

[tom7035]

I don't know about 70's cars, but mine has a relay switch under the bonnet associated with the 'kickdown'. You may have similar, and another avenue to check.

 

[guydewdney]

very likely to be oil level in the gearbox... this happened the otehr day to my GF's sprinter - the filter and valve body were minging with horrible goo...

so 1) change fluid and filter

Then - go through the system - if its the same as the later boxes, theres a kickdown solenoid on the back of the box (RHS)

I have the M110 and W114 official manuals that i COULD dig through - but they are HUUUUGE (like 3" thick each, and the engine alone has two manuals...)

It does have an electrical kickdown switch btw...

 

[foursail53]

Thanks Guydewdney, Timn, pascal and all the others who were kind enough to answer. This is my first Mercedes (shock horror) and it means a lot to get good advice. I checked systematically as advised. The kickdown is now working - it appeared to be incorrect petrol/air mixture inhibiting the engine - but your advice will also make me suspicious of the various switches and tubes involved as it may be an intermittent fault.

Thanks again all........