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1983 300TD, 115,000 miles. Anthracite Gray
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163 Posts
Discussion Starter #3
Is it by any chance this shutoff valve? How to Repair Your Shutoff Valve
Close, but no. That's the valve that actually shuts off the power. The one I included the link to is at (or near; I'm not sure) the ignition switch. It passes a vacuum to the shut-off valve in your link, causing the engine to shut off. That's what's broken on my car.

Thanks,
Jim
 

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1981 300D
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6 Posts
I don't know if you've done it yet, but I just did one a few days ago. Managed to do it without removing the ignition assembly. Not easy. I used the smallest ratchet I could find and put a flathead screw driver bit into whatever size socket would hold it. I put tape around the bit to seriously wedge it into the socket. Strained a lot of muscles but was worth it not having to remove the ignition switch set up.
 

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1982 300CD
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5,157 Posts
I did it some years ago. I think I remember loosening the steering column support. Wasn't all that complicated, in any case.
But then I may have done it while replacing the tumbler...
 

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1982 300CD
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5,157 Posts
Maybe so. The details are a little fuzzy now, though. In any case, it isn't so complicated that you would need instructions.
 

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1984 300D
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5,070 Posts
Does anyone who has done this before think replacing the Original screws with Allen or Torx type Screws would Help when it comes time to insall the Switch?
 

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1984 300D
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5,070 Posts
The Rear Wheel Bearing Wiki sucks and someone following the instructions is going to damage their Rear Wheel Bearings just as the Guy that Posted the Wiki did.
The Front bearings are fist in the Wiki the Rear Wheel Bearings are further down. Below is the part where He ruined His rear Wheel Bearings.

"That will be obvious by sound and feel. Later when you torque that nut back down you may feel a little mushy spot just before it bears down seriously ... that would be the bearing races scootching that last fraction of a millimeter. That 340 ft/lbs of torque "pre-loads" this system and keeps things true while under working stresses of vehicle weight and operation.

8- clean everything very carefully ... grease liberally... put it back together the way it came apart. A) both inboard and outboard outer bearing races, lots of grease, outboard grease seal, inboard inner bearing race, spacer, inboard grase seal, inboard grease seal mating ring and lastly nut plus 340 ft/lbs torque.
I apparently was not as thorough as I should have been. Within a few months I began to hear a whaa whaa whaa sound at my left rear (that's the one that self destructed) and I had to do it over. When I took the bearing out the second time, up really close inspection showed the new bearing surfaces looked a little like the surface of the moon. Apparently one metallic fragment in the grease can fracture the new bearing surface and multiply into many fragments in a cascading patten of eventual quick destruction."

There is no pre-load Torque at all and there is a Metal Collar that you should replace. That Collar is how you adjust the Bearing Clearance/End Play.

You get a Dial Indicator with a Megnetic Base and install that so that you can measure the in and out play of the Hub. As you tighten the Nut you will eventually start to crush that New Collar you installed. You keep checking the Dial Indicator as you tighten on the Hub Nut intill the New Collar is crushed sufficently to give you a Bearing Clearance/End Play that is within the spec.
If you overtighten and over Crush that Collar you have to take the Hub out and start over with another New Crush Collar. However, slide Hammering off the Hub or other methods of removing the Hub can also damage the New Bearings that you install.
So you need to be exceedingly careful the first time and do it right the First Time.
The DIY links and Wiki on the below site have been there and picked over anc commented on by the Forum Members to correct any faulty instructions. They were also added to they lists by a Moderator who is a Trained and still currently working in that profession Mechanic.
 

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1982 300D-Turbo
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209 Posts
The Rear Wheel Bearing Wiki sucks and someone following the instructions is going to damage their Rear Wheel Bearings just as the Guy that Posted the Wiki did.

Um... that's the power of the wiki, if you think it sucks and can write a better one, change it. You just hit "edit"
 

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1984 300D
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5,070 Posts
The Rear Wheel Bearing Wiki sucks and someone following the instructions is going to damage their Rear Wheel Bearings just as the Guy that Posted the Wiki did.

Um... that's the power of the wiki, if you think it sucks and can write a better one, change it. You just hit "edit"
That is not the power of the wiki; I saw that wiki it must be at least 2 years ago but never kept the address of the Site. Your posting the site jogged My Memory.
So for at least 2 years it could be misleading people.

I don't have any pictures to contribute to the writing and don't plan on pulling my Rear Hub until I have a problem.

As for writing another Wiki who ever runs the wiki ought to pull the rear bearing part out of the Wiki.
After all I have no responsibility to write a correction.
 

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83' 300d
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343 Posts
How do you know if your ignition shut off valve needs replacement?
Get a Mity Vac or the like - use it to put artificial vacuum on things that are vac powered. Things like that ignition switch vac valve, locks, etc will hold a vac after you put it on it. If it leaks down, you have found the source of your vac leak. Go around testing individual components and you'll find your leaks.

Btw, that Wiki for the ignition switch valve is horrible. I'd write a new one if i knew how to do the job properly. Anybody???? Anybody try taking the cluster out? There's no clearance under the dash for taking that little valve out... i just left mine leaking...
 

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1976 Mercedes 300D, 1999 Ford F-250 7.3 liter diesel, 2006 VW Jetta TDI
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I worked on my vacuum change over valve yesterday, fortunately I didn't need to replace it, just the nearly 40 year old vacuum connectors needed replacing to restore vacuum.

On a 1976 300D, the vacuum valve is directly behind the instrument cluster attached to the ignition key tumbler assembly. I saw no easy way to get to it from below, but popping the instrument cluster out is surprisingly easy once you know how. It's just a press fit, so all you need are a couple of coat hanger wires with about a 1/4-1/2" bend in each. Work those in on either side of the cluster, turn them to the inside so they engage the cluster body & pull. In my case, they didn't "engage" so much as they allowed me to wiggle the instrument cluster out of the dash (a bit, it only comes out about 2-3" or so unless you start removing speedo cables & such). The link I found to make the tools & other helpful things was here.

Once you've got it out, the vacuum change over valve is easily seen on the right hand side of the opening, at the bottom. The outside connection is for vacuum supply (furthest from ignition), and the inside is to the fuel shut off valve. In my case, the supply line's connectors had simply shredded so it was leaking vacuum, so when I turned the key off, the switch (it's actually a small solenoid) moved, but there was no vacuum to be supplied to the shut off switch, so nothing happened. Once you have it repaired, you should be able to see vacuum on the supply side when the key is on or off, and you should only see vacuum on the shut off side when the key is off.

Once I knew how to do it, the actual fix took less than 15 minutes, but it was hours of research, finding out how to remove the instrument cluster, how to make the tools to do so, getting a Mity-Vac so I could check vacuum lines to make sure it was the change over valve, etc. Plus for a couple of days I used the Mity-Vac as an in car shut off system instead of using the manual fuel shut off valve under the hood.

Now the car shuts off like it should again & my wife is happy (it's her car).

Edit: I just realized this forum was for the 123 chassis, so this description of the cluster removal may differ from my 115 chassis. Sorry for any confusion.
 

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1982 300CD
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If you remove the kick panel, you can reach up and push the cluster out from behind. Then you don't risk damaging the sides of your dash.
 

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1976 Mercedes 300D, 1999 Ford F-250 7.3 liter diesel, 2006 VW Jetta TDI
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8 Posts
If you remove the kick panel, you can reach up and push the cluster out from behind. Then you don't risk damaging the sides of your dash.
This may well be correct for a 123 chassis, on my 115 there's no room for my hand to get to the cluster from behind, nor my wife's, and she's far smaller than I am.

 
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