W201 noise on start up

[Charles Morgan]

Since the central locking stopped working on my 190E I get a loud medium high pitched drone from the area of the rear offside passenger seat which comes on when I open the door (it might be on before that) and continues for some time after starting up, but seems always to end when I get moving.

Any clues as to likely source, cause and repair?

 

[BlackC55]

Probaby the PSE pump running on.

Try disconnecting it for 5 mins then re-connecting it and see if the CL starts working

 

[John Jones Jr]

That's the vacuum pump making the noise. You've either got a vacuum leak or faulty pump. More than likely the former.

 

[Charles Morgan]

Finally got round to having a good look today - the air hose had become detached from the pump, most probably when the rear jacking point was done, so a quick reconnection has sorted the problem.