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Car Forum / Mercedes-Benz Cars / August 2007

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'79 W123 300TD ShutOff Valve

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Tom Plunket - 30 Jul 2007 07:16 GMT
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=105650

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=106522

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!

--
-->> T.G. Lambach <<-- - 30 Jul 2007 07:37 GMT
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.

Signature

© 2007 T.G.Lambach. Publication in any form requires prior written
permission.

Tom Plunket - 31 Jul 2007 04:03 GMT
> 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.

Ok, I'll see what I can find.

> 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.

Ok, cool, thanks.

> 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.

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

> 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.

Ah.  Thanks.

> Sounds like you're having fun with your diesel.

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!

--
Karl - 01 Aug 2007 00:21 GMT
To clean the brown/blue stripe vacuum line that goes to the shut-off switch: Get a spray can of
Berrymans Brake Cleaner. [NOT the cheap sh!t at Smucks or Pep Boys]
http://www.berrymanproducts.com/Portals/0/HR%20LINEART/2421-LA.pdf
Start the engine. Disconnect the line from the shut-off diaphragm. Turn off the key. Spray Brake
Cleaner into the line. It will circulate thru the line, thru the switch, thru the brown line, and
out the vacuum pump into the fresh air source. Let it run for a little while after you stop
spraying.

> > 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
[quoted text clipped - 46 lines]
>
> --
Tom Plunket - 13 Aug 2007 01:53 GMT
> To clean the brown/blue stripe vacuum line that goes to the shut-off
> switch: Get a spray can of Berrymans Brake Cleaner.

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!

--
Tom Plunket - 06 Aug 2007 01:13 GMT
T.G. Lambach wrote:

> 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.

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!

--
Karl - 06 Aug 2007 05:23 GMT
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=123190&M=617%2E912&GA=722%2E118405&G
M=716%2E005++++++++++++++717%2E400&CT=M&cat=143&SID=13&SGR=090&SGN=03

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=123190&M=617%2E912&GA=722%2E118405&G
M=716%2E005++++++++++++++717%2E400&CT=F&cat=318&SID=46&SGR=105&SGN=05

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=123190&M=617%2E912&GA=722%2E118405&G
M=716%2E005++++++++++++++717%2E400&cat=318&SID=80&SA=+56153

If it shuts off, stop, you have fixed it :)

> T.G. Lambach wrote:
>
[quoted text clipped - 33 lines]
>
> --
trader4@optonline.net - 06 Aug 2007 18:30 GMT
> 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
[quoted text clipped - 91 lines]
>
> - Show quoted text -

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.
Karl - 06 Aug 2007 19:10 GMT
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.

> > 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
[quoted text clipped - 99 lines]
> found exact same thing.  It may be stress from vibration or temp
> change at that point that makes it more susceptable.
Tom Plunket - 16 Aug 2007 20:35 GMT
> 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.

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

> 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.

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.

> 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.

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!

--
Tom Plunket - 18 Aug 2007 04:48 GMT
> 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.

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.

> 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.

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.

> On vacuum line, does size matter?  The local parts stores have a couple
> of different options...

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

> 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.

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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