Maybe you knew this but it's news to me. The key switch signals a switchover valve to actuate the engine shut-off valve. It's the same shut-off valve and vacuum source with a switchover valve bolted to the intake plenum. Might be the key to remote start for older Diesels.

Also the W140 does away with the vacuum amplifier for the transmission modulator. The vacuum controller on the side of the IP looks the same but there's nothing between the controller and the modulator other than the line that connects them.

Sixto
93 300SD

I just got the W140 vac diagram thanks to Chuck, thanks Chuck its very precise and accurate and learning new things, my car 50% does not shut off, check shut off valve with migty vac and it is working. now I need to learn how to check the switchover valve (item Y9/1) any body out there knows to test the eletric part of it and vac readings. Here is the diagram.

Attached Thumbnails

 

your pic is upside down...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

upps!!!! here we go again

Engine running, power to solenoid, no flow from diagram item 140 to diagram item Y9/1, line to engine shutoff actuator vented to diagram terminal a. Engine off, no power to solenoid, flow from diagram item 140 to diagram item Y9/1, line to engine shutoff actuator under vacuum from diagram item 140, no flow to/from line to diagram terminal a.

Sixto
87 300D

I've been working on mine. This isn't quite right. According to alldata, a relay N17/3 is actuated for for about 3 seconds (verified) after the engine is switched off and operates the key-operated engine stop switchover valve (Y9/1). A vacuum of about 500 mbar is present at this valve which when actuated/switched-over operates the the shutoff actuator pneumatically moving the control rod into the stop position.

there are time delay relays that were used for some purposes, I once found a relay lying on the seat of a car in a yard, it was a bosch 40A relay but had a 4 second delay in switching off. I had no use of it so chucked it in the bin.

a regular vacuum solenoid like a toyota purge valve (cheap as chips) can be activated by such a delayed relay for swaps.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

DO you know this relay location, i cant find it

This knowledge could help on some of the engine swaps,putting MB diesels in vehicles that were originally gas. Don

__________________
Red Green "This is only temporary,Unless it works!"

97 E300D 157000 miles
87 300TD ?141k? miles

As you know I had problems with the engine not to shut-off with key, some times will shut-off and somes times didn't. Well after going testing w/mighty vac the shut-off valve was working properly. To thanks to Chuck diagram, I was able to identified the cross over valve, base on sixto's comments of electric switch (Cross over valve) above the shut-off valve, for testing purposes went to local wrecking yard and got two for few bucks, installed and whala!!!!!! is been working for a week not a single problem with shutting off. Here are some pics fo the cross over valve is the upre unit whit two vac hoses on the left.

Attached Thumbnails

   

Do you have the part number for that delay relay?

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

What's the delay for? Why would you want to wait 3 seconds for the engine to shut off? Sounds like a ricer turbo timer circuit

Sixto
87 300D

I assume it is hooked up such that it runs the cutoff solenoid for 3 sec when the key is turned off.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

That makes sense. I figured it was always powered to vent the actuator when the key is on ON. Your way powers it only for 3 seconds each start and stop cycle.

Sixto
87 300D

I was planning on just using a simple solenoid actuated vacuum shutoff on my gas-to-diesel conversion. I would be very interested in a system where the vacuum to the shutoff would only be provided for 3-4 seconds after power was disconnected from the device. (I wouldn't want to be driving around with a solenoid that had to be activated to vent vacuum such that any malfunction would shutoff the engine.) So the way it would have to work for me to be interested would be for the vacuum device to have both a continuous and switched power source and a delay mechanism such that when there was an interruption in power on the switched circuit, the continuous circuit would activate a solenoid for the timed interval to perform the shutdown, and thereafter shut off the circuit so the solenoid wouldn't be active running off the battery. Is that the concept we're discussing?

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica