Mercedes Sprinter 208D. Vacuum Shut Off Valve

[donaldshorrock]

Hi, Guy's

I have a Mercedes Sprinter 208D 1996. The problem i have is that the engine runs on after turning off the engine.
I think i have narrowed the problem down to the ignition switch. There is a good vacuum one side of the switch and the otherside has much less suction.
I pulled both rubber pipes from the ignition switch and put them together and the engine imediately stopped with the key in the off position.
Do you think there maybe some kind of blockage from the small distance from the inlet to the outlet side.

Regards Don.

 

[brandwooddixon]

More probably a leak.

 

[donaldshorrock]

Hi.

Yes it was a leaking ignition switch. Its now repaired with a bit of gasket sealant which i then cured before turning the engine over so none would get dragged into the vacuum system.

 

[sprinter208d]

Hi there mine is doing exacly the same is this an easy repair? and is this a common problem?

 

[Roxie]

Because there is no electronic control on the fuel system of the OM601 Engine the engine stop is controlled by a vacuum actuator in the top of the fuel pump. This is the small round tin can with a pipe coming out of it.

The vacuum system is supplied from the small pipe at the brake servo or at the Vacuum pump. This vacuum is controlled for the engine stop by a small valve on top of the Ignition switch. If it stops working it could be a leak in this vacuum supply to the valve. As this supply also controls the fresh air heater flap and the Head lamp leveling system along with the fast cold idle switch you need to make sure that you have a good vacuum pressure at the valve. You can do this fairly well by removing the pipe and putting your finger over the hole you should be able to feel it sucking and hear it when you take your finger off. If you have no vacuum you will have to follow the pipework back isolating the various actuators until you find the cause of the leak.

Should you have a good vacuum at the stop valve you will have to check the opperation of the valve. You could do this by checking for a vacuum at the fuel pump when the engine is running and the key is off. If you have a good vacuum at this actuator then it is likely that the Diaphragm is split in this actuator. It is easily changed the large nut underneath it screws away from the actuator and then it just lifts out and unhooks from the lever in the pump.

If you have a vacuum pump you could try to actuate this actuator from an external pump. If you have a vacuum guage you can test the supply vacuum pressure it should be over 700mbar.

 

[Roxie]

Hi, Guy's

I have a Mercedes Sprinter 208D 1996. The problem i have is that the engine runs on after turning off the engine.
I think i have narrowed the problem down to the ignition switch. There is a good vacuum one side of the switch and the otherside has much less suction.
I pulled both rubber pipes from the ignition switch and put them together and the engine imediately stopped with the key in the off position.
Do you think there maybe some kind of blockage from the small distance from the inlet to the outlet side.

Regards Don.

Yes it sounds like the little Switch/valve is not opening fully I dont know how much they are but surely they can't be too expensive. If it is trying to work it might respond to a little bit of sillicon grease or wd40.
Simple job to replace it.