'79 W123 300TD ShutOff Valve

The car's taken a second or so to shutdown ever since I got it about nine months ago (wow the time flies).
While running heav's suggestion of the miracle oil in a tank of diesel,
the shutoff completely failed to function. It didn't shut off the first day, then that night it got pretty cold and shut down after a couple of seconds, and it hasn't shut down by itself since.
So today I finally got to looking at it. First order of business was to hook the ol' MityVac up to the shutoff valve. Let's just say I should have used an older hose 'cause the shiny new one is now full of oil.
Obviously, this puppy has gone bad. My questions, then, are thus:
It appears that I need this part, and gaskets are available separately, which add another $1.50 to the price so I might as well...
http://www.performanceproducts4benz.com/productpage.aspx?pid 5650
However, this guy is right nearby in the schematics, but I'm not following what it's for. It says "from engine no. 93508", but as of yet I've been unsuccessful at locating the engine serial number. I know where it's supposed to be, and I see a string of numbers that contain '617', but the numbers are otherwise non-sensical to me. Anyhow, this guy's almost $200 and I'm really hoping that it's not a critical piece of the puzzle.
http://www.performanceproducts4benz.com/productpage.aspx?pid 6522
Finally- when I do this fix, how critical will it be for me to replace the vacuum line to the key? I'd really like to avoid opening my dash up, especially considering the manuals talk about pulling the cluster rather than accessing it from below. I guess it wouldn't be the end of the world though since I need to replace my idle speed cable at some point anyway. Oh, and until I get the parts and get it fixed, should I just run with the vacuum line disconnected so I don't continue to suck oil into it?
I'll wrap with the following fuel update: over the past 1700 miles I've put only 13 gallons of petroleum-based fuel into the car. Most of the rest of the fuel has been "virgin" soybean oil, but as of last week I've got my filter and pump and set of 55 gallon drums setup all in order and have been pumping used veggie oil from a couple of local restaurant friers. The car runs super smooth on this stuff, which is unsurprising because of the lubricity of vegetable oil (and the fact that even 5% biodiesel can return pump diesel to the same lubricity that it had with all of that gnarly sulfur).
thanks, as always. You guys are great.
-tom!
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The engine number is in the block, not the cylinder head, behind the oil filter canister. Yes, the number starts 617.xxx-serial no. Use a flashlight and wipe it off with a paper towel.
The shut down device that your car needs is the $39 item. No, don't mess with the vacuum line to the key, just replace the device; it will be fine.
I'd remove the vacuum line from the defective shut down and plug it. You will then need to shut off the motor by using the STOP lever on the throttle linkage.
The second, white plastic vacuum valve shown is mounted on the injection pump to control the vacuum to the transmission's shift modulator. The web picture is upside down, that's why the part is not recognizable.
Sounds like you're having fun with your diesel.
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-->> T.G. Lambach <<-- wrote:> The engine number is in the block, not the cylinder head, behind the oil

Ok, I'll see what I can find.

Ok, cool, thanks.

Oh yes, I've gotten quite skilled at that process over the past week.

Ah. Thanks.

Yeah, it's pretty cool. There's some suspicion that it's not entirely cleaner-burning than diesel fuel but the way I figure it is it doesn't have any environmental impact to create (since it's already been used for its "intended" purpose) and the total cost so far has been a $5 5-micron filter, a $15 hand pump and about $10 for the vinyl hose and fitting to put on the pump. Considering the only recurring cost is going to be a $3 filter (once I start getting 'em in bulk) every 40-60 gallons and a few extra minutes at a couple of the restaurants I go to anyway, I'm feeling pretty good and am certainly ready for fuel to hit $5/gallon this summer. ;)
Gotta run- gotta get to the Chinese joint to pick up another 10 gallons of the brown gold.
Thanks a lot for the tips on the engine and vacuum stuff. I stared at a couple of diagrams for a while last night, and it's starting to come together. I just wish I knew what to do to replace the spring in the passenger door lock actuator, 'cause the mechanism goes up and down but it's no longer connected to the actual lock, and this piece doesn't show up on schematics anywhere that I can find (including at the dealer!)...
thanks again, -tom!
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Karl wrote:

Ok, I got the Berryman's, but it says not to let it get on plastic or rubber parts. Guessing that most of the vacuum system is vacuum or rubber... I guess I have nothing to lose since the system appears at first glance to be full of oil. Ugh.
-tom!
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T.G. Lambach wrote:

I got the new shutoff valve installed, but sadly it didn't fix the problem. Or more specifically, it's not leaking but the engine doesn't shut off on its own. However, if I suck on the shutoff valve, the engine does shut off. So...
I traced the problem up a bit to the "main" T; the T from the vacuum line between the master cylinder and (presumably) the vacuum pump. I noticed the bottom of the T was all oily, and popped the "system" line (the light gray one that goes off from the T) out to see that it's all oily as well.
Hooking the vac gauge up to the T indicates that the pump is pulling about 20in/50mm Hg. However, pumping on this yields me nothing; something is clearly leaking. Pulling off the splitter/valve (is that a check valve?) that goes to the vac reservoir (yellow/gray) indicates oil in that neighborhood too, although I don't know if it's made it through that splitter.
I suppose the next phase of the attack is to pull everything piece by piece, and also find something that can allow me to effectively provide vacuum through the keylock valve. I don't happen to have anything that'll fit into the brown line nor anything that's snug enough around the outside of that line to shut the engine off...
Grrr...
Thanks for the help thus far, though.
-tom!
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With your vacuum gauge in the nipple on the brake booster line and having a good seal, you should have 25". Anything less is not good. Does your 20" vibrate or is it steady? If it vibrates, follow the black booster line down to the vac pump. Does it screw on to the top onto a larger fitting? The line nut is 17mm, the fitting under it is 19mm. Remove the line and get a flashlight and look into the fitting hole. Is it empty? If yes, you have lost the 3rd check valve. It self-destructs and falls into the pump. The valve is available seperately from the dealer. You need to remove the front cover of the pump and retrieve the 3 pieces that falls in: a spring, a plastic plunger, and a disc of metal with 3 points on it. When you remove the cover pay CLOSE ATTENTION to the direction and position of the other 2 check valves!!! This only applies IF you have pump #14 here:
http://www.detali.ru/cat/oem_mb2.asp?TP=1&F 3190&Ma7%2E912&GAr2%2E118405&GMq6%2E005++++++++++++++717%2E400&CT=M&cat3&SID&SGR    0&SGN The fitting is #20, part number 004 997 18 72
Then...... You need to cap off the other lines, i.e. the yellow and yellow/black for the door locks and the green or red for the ACC system. Just leave the brown line and vacuum gauge connected. Brown is shut-off. Still have vacuum? Now move the gauge to the brown/blue line [remove it from the shut-off valve]. Just have the brown line connected to the booster line, all others capped off. Shut off the engine. You should have the same amount of vacuum that you had in the brown line test.
No? You have a problem with the shut-off valve on the steering lock. Motor oil destroys the two rubber hoses. they swell up and leak. Pull the cluster and replace the rubber hoses. They are #44 here: http://www.detali.ru/cat/oem_mb2.asp?TP=1&F 3190&Ma7%2E912&GAr2%2E118405&GMq6%2E005++++++++++++++717%2E400&CT=F&cat18&SIDF&SGR5&SGN After you replace them, flush the valve and lines out with Brake Cleaner like I said in my 1st reply.
If the vacuum is the same: Connect the vacuum line back on the shut-off unit. The engine should shut off IF you correctly hooked the arm on to the lever in the injection pump. You should remove the 4 screws holding the cover on the top of the pump and rotate it so you can see if you hooked the arm.
If it shuts off: Reconnect the red or green vacuum line. Start the engine. Wait about 30 seconds. Shut off the engine. Does it stay running? Uh oh, you got big problems in the dash/ servo unit area. Does it shut off? Good. Now connect the solid yellow line. That one is direct to the drivers door vacuum switch for the locking system. Start the engine. Shut it off. Does it shut off? If no, lock the drivers door. The other locks should lock and then the engine should stop. If yes, you have a leak in either the RF, LR, or RR doors, or the rear hatch. NOT the gas flap door, it only gets lock vacuum. It does not get unlock vacuum. A spring unlocks it when you loose vacuum. If it shuts off with the doors unlocked, now connect the yellow w/black hose. That one goes to the door lock vacuum reservoir. It takes a while to fill it. Leave the engine running about 5 minutes before you shut it off. Does it shut off? If no, you have a leaking reservoir or the line to it. #35 here:
http://www.detali.ru/cat/oem_mb2.asp?TP=1&F 3190&Ma7%2E912&GAr2%2E118405&GMq6%2E005++++++++++++++717%2E400&cat18&SID€&SA=+56153 If it shuts off, stop, you have fixed it :)

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I'd check where the vacuum hoses go through the rubber grommet on the driver side firewall. A few go through the same grommet there, ignition shut off, door locks, etc. I had two break off right at that spot. While I was looking for the leak, I wiggled them a bit and one broke off in my hand. Few months later, had another problem and found exact same thing. It may be stress from vibration or temp change at that point that makes it more susceptable.
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When I said "Uh oh, you got big problems in the dash/ servo unit area." it leads to another very weak point on the 123 body with the servo system: Battery acid and the servo vacuum lines below the battery. The acid LOVES the plastic tubing. The rubber hoses fair better.

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Karl wrote:

Ok. I got 21.5" steady last night when I hooked into vacuum at the T. Could my booster be leaking?

Interestingly, hooking the vac gauge up to this cross-coupler, the X thinger, disconnecting each of the "output" connections one after another and hooking up the vac gauge I got like 2" at each one. So I guess that implies either the cross is leaking or the gray line, which seems really odd to me to have it that low, but then giving a pump on the X piece while connected to where the windows and reservoir would have been, and I got it to shut off. So off I go to the dealer to see if I can't get some of those Xs and maybe a few Y connectors, a few more of those valves, and maybe even some vacuum line.
On vacuum line, does size matter? The local parts stores have a couple of different options, but all of it limited to 3' lengths so its value is somewhat limited for a prospective whole-car-vacuum-system-filled- with-oil replacement job.

I'm curious where to find rubber hose like this, too, because so far my trips to the car parts stores have yielded little that seemed appropriate.
Thanks a lot for the comprehensive reply.
-tom!
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Tom Plunket wrote:

Turns out that not only was I leaking at the key switch, but also one of those yellow dual-check valves (I'm guessing that's what those are?) was also leaking. ...noticed as it was whistling when I had the hood up and the car running with the key in run. Got a couple of those for like $9 a piece at the dealer.
So I noticed last night, as I had forgotten to turn the key off when continuing to diagnose my problem, that I had vacuum to the key switch as long as the car was running. Since the rubber hose connecting to the shutoff valve also held vacuum, I came to the conclusion that I would have to pull the instrument cluster. Wow what a PITA; the speedo cable doesn't really give you much to play with...
Anyway, I popped some new rubber on the hoses at the key switch and voila shutoff as expected.

They have 'em, for about twice the cost of the Performance Products prices. I got a few 'cause the difference would have been made up by shipping anyway.

The dealer sells it by the meter, I got a 4m roll for like $12. It's bluish white in color.

This hose is also sold at the dealer for virtually nothing.
So yay, I've got my shutoff working again. I think I lived for three weeks with this crap. Ugh what a pain. Now it's done though so I can get back to watching Battlestar Galactica and playing video games. :)
-tom!
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