Help Please!!!!!

[mercedes190d]

Hello all,My mercedes 190 diesel isnt shutting off when i turn te ignition off.I can even remove the key and it will continue to run.ive been told by mercedes that it is a vacume leak! and they sold me this little valve that fits on the back of the ignition.Can anybody tell me how to change this valve?


Many thanks
John

 

[brandwooddixon]

I remember a recent thread detailing this. It also stated that there was a red lever that you could use to shut the engine off.

I don't have any experience of your car myself, but a quick search should give you an idea.

 

[television]

Its a vac leak either just behind the ign switch or pipe off

 

[wireman]

You have an M series injection pump with a pneumatic shut off. The thing works by applying vacuum to stop the engine, a pipe comes from the vac pump to the switch and then back to the pump mounted bellows.

The engine stop bellows is mounted atop the pump easy to see but a real ball ache to remove, hopefully its the valve that you have been supplied. this is mounted on the steering lock part of the ignition switch, to change it remove the steering lock (Haynes book of lies is good in this respect) and its there right on the back of the lock where you cant see it when installed.

Take the two pipes off and join them this should stop the engine, if it does then it is indeed the valve.

If it dont then you have either no vacuum or a dud bellows,
connect a vacuum gauge to the vac pipe and with the engine running there should be about 20"Hg vac available, if not check all the vac connections especialy the blobby bits that split the vac system up for each vacuum operated system (headlamp&heater), short rubber tubes are used to join the nylon tubes to the vac parts and these may be tired out and split.

If you suck on the engine stop pipe it should not leak and you can stick your tongue (whilst still sucking) onto the pipe end, it should hold the vac indefinately.

The pump is not easy to get at so completely remove the air filter housing from the inlet manifold (4x M6 nuts) and take the rubber joints off the inlet maniflod to air box joints.

The bellows is now almost accessible, at least its vac tube is, so put the vac gauge onto the pipe that attaches to the bellows and check for 20" vac whilst the engine is running and the key is off, if you get a vac its the bellows at fault.

Now to change the bellows, tools required 10mm af ring, combination, socket and open end (short) spanners plus about one hour or more, oh and a swear box.
The stop bellows is about 35mm dia held with 2 clamp bolts, it is partialy hidden beneath the barometric compensator bellows (65mmdia) on top at the very back of the pump govenor housing.

Clean the pump of all muck in the vicinity of the bellows.

The bellows is clamped down by two longish M6 bolts with loctite, they need to be removed with whichever of your 10mm spanners will get at the bolt (dont forget that if you flip the open end you can turn the bolt one twelfth of a turn) since loctite is used these bolts are game to the last (it took me 45mins just for one bolt), once removed the bellows just lifts in and out, hooking into the fuel shut of mechanism as it is placed in. Once you have got the new bellows back in clean up the screws and apply some screwloc before the bolts are put back in then wind the bolts back down and nip them tight.

The innards of the pump are exposed with the bellows removed take great care not to allow anything inside or else it could wreck the pump.

While the engine is running without its air box it will try to hoover up anything that gets near to the inlet manifold, do not allow this to happen, it will wreck the engine.

A small handed boy is of great use to gain access to the clamp bolts, his hands go where mine won't.

When it is all working correctly the emergency stop lever should stay down after the engine is stopped and only return when the key is turned on again, even overnight.
If the lever returns back to the run position there is a leak on the system.
My unit had a microscopic hole in its bellows diaphragm and cost £19.50+vat from Bosch.