how does a W124 E300D physically turn off?

[SilverSaloon]

hi

OM606 multivalve in a W124.... (non turbo)

i was wondering, how does the car actually switch off when you turn the key... i know its a vacuum system, but is there a specific control unit for this in the engine bay, and if so where is it?

thanks

Derek

 

[nick mercedes]

hi

OM606 multivalve in a W124.... (non turbo)

i was wondering, how does the car actually switch off when you turn the key... i know its a vacuum system, but is there a specific control unit for this in the engine bay, and if so where is it?

thanks

Derek

There's no control unit as such, just the thing on the pump?

 

[Number_Cruncher]

W124 diesels switch off in a very simple, but slightly unusual way.

It's entirely vacuum operated, and there is no electronic involvement at all.

When the engine is running, there is no vacuum ported to the capsule on the pump.

When you turn the key off, vacuum is ported to the capsule on the pump, which moves the fuel rack to the no fuel position, and the engine stops.

So, you actually apply vacuum to stop the engine. This means that a vacuum failure would go undetected until you try to stop the engine.

This is why you also have a stop valve on the fuel filter - some fools replace it with the cheaper blank bolts of W210s when the valve leaks.

 

[SilverSaloon]

When you turn the key off, vacuum is ported to the capsule on the pump, which moves the fuel rack to the no fuel position, and the engine stops.

...

some fools replace it with the cheaper blank bolts of W210s when the valve leaks.

thanks

where is the capsule exactly? i'd like to check it out to ensure its ok...

i temporarily fitted a cheaper W210 bolt on mine until i got another W124 one - i always thought, worst comes to worst i would pull a clear pipe to stop the engine.

 

[Druk]

I'm guessing it's the white nylon doofrie (sp?) on the top right of the top pump in this pic.

 

[whitenemesis]

W124 diesels switch off in a very simple, but slightly unusual way.

It's entirely vacuum operated, and there is no electronic involvement at all.

When the engine is running, there is no vacuum ported to the capsule on the pump.

When you turn the key off, vacuum is ported to the capsule on the pump, which moves the fuel rack to the no fuel position, and the engine stops.

So, you actually apply vacuum to stop the engine. This means that a vacuum failure would go undetected until you try to stop the engine.

This is why you also have a stop valve on the fuel filter - some fools replace it with the cheaper blank bolts of W210s when the valve leaks.

How is the vacuum ported to the capsule? Are there vac lines running to/from the ignition barrel?

 

[219]

I'm no expert on Diesels , but my pal James had a 124 300D and he stopped it by sucking on a vacuum pipe on the nearside of the engine compartment , just forward of the bulkhead .

There's also a vacuum switch incorporated in the ignition switch .

 

[Number_Cruncher]

Yes, the stop capsule is on top of the injector pump, and yes, the diesel key switches have a vacuum switch on the back of them.

It's a very odd system in that you need to supply a signal to stop the engine - rather than on a petrol engine where you supply a signal to allow the ignition/injection to activate, and remove the signal to stop the engine. This is why there is a second means of stopping the engine - on the older engines, the stop lever on the pump was accessible, on the newer ones hidden beneath the manifold, there's a valve on the fuel filter.

 

[franey]

Mercedes Diesel Shut Off Valve on eBay (end time 10-Mar-11 18:02:53 GMT)

 

[3ayg]

Digging up an old post here but I'm having a nightmare with my w124 I've done an engine swap, it was a 230e but it's now got a om606 it's running just fine starts on key but doesn't turn off on key is there a way I can add a universal 12v vac pump to shut the fuel off?

 

[V12]

Digging up an old post here but I'm having a nightmare with my w124 I've done an engine swap, it was a 230e but it's now got a om606 it's running just fine starts on key but doesn't turn off on key is there a way I can add a universal 12v vac pump to shut the fuel off?

Did you change the ignition lock to a diesel one?

 

[3ayg]

Nope I didn't realise I needed it when I had the donor car d'oh! In my giddyness to hear it fire up I completely ignored it... thinking I may be better off buying a full lockset and ignition from a diesel rather than mess about with a 12v pump?

 

[V12]

You only need the lock, you can use the cylinder barrel from your existing petrol one to retain the existing key and lock set.

 

[Druk]

If it's the non-turbo 606 you can use the vacuum for the gearbox modulator to switch to the stop actuator on the IP. An electric changeover valve from a C or E class EGR valve works great. Plenty of them in the scrappies.

 

[bolide]

What are you going to use to drive your brake servo? There's no inlet manifold vacuum in a diesel

Nick Froome

 

[carat 3.6]

An electric changeover valve from a C or E class EGR valve works great. Plenty of them in the scrappies.

Good thinking.

 

[V12]

What are you going to use to drive your brake servo? There's no inlet manifold vacuum in a diesel

Nick Froome

Is this a trick question Nick? Surely he's using the vacuum pump. Sounds like the engine and ancillaries came from another W124 so he would have had the associated pipe work as well I'd imagine.

 

[3ayg]

If it's the non-turbo 606 you can use the vacuum for the gearbox modulator to switch to the stop actuator on the IP. An electric changeover valve from a C or E class EGR valve works great. Plenty of them in the scrappies.

that sounds like the best way round it! managed to track down one ignition barrel and its not cheap... can you elaborate on how exactly to do this? where is the gearbox modulator? and what is the electric changeover valve? im pretty technically minded and once pointed out I will probably get it

And yeah I just swapped everything over, apart from the ignition the swap was much easier than expected, read a lot of neigh say before I started that kinda put me off, in the end it made me want to do it even more just vacuum system that im struggling with at the minute but ill figure it after plenty of head scratching

 

[3ayg]

For anybody else looking for answers on this I have now fixed it.
I have deleted the EGR valve all together, because of this the EGR Modulator was redundant, I cut the wires to the modulator so I could use the standard plug and wired them into an ignition source & earth and directed vacuum to the shut off valve when the ignition was off.
it took a bit of messing but using a probe with the engine running I just put my finger over the vac pipes to work out the direction & went from there, once you start its pretty straight forward and just takes a bit of common sense