Yesterday was a nice warm day here in NJ, so I decided to give my 300SD a fresh shot of Delvac 1300. Afterwards, I fire her up for a little bit to let the new oil circulate and fill up my oil filter, then I turn the key to shut off, and it would not shut off but instead starts making these strange rattling noises. So I turn the key back to on, and the rattle stops and engine idles stably... I repeated the same thing about 3 times, and on the third time, the car finally shut off.

So far this hasn't repeated, but usually it takes several seconds after turning the key to off for the engine to shut off, and I can hear a bit of a rattle, like something's trying but slipping...

What's the shut-off mechanism in my car, and what could be the culprit?

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84 300SD - bought in April '06 with 237,000 mi

There is a vac operated shut-off valve on the back of your injection pump. It sounds like the valve is not working. Use a mity vac and plug it into the line that goes into the shut-off valve, and start the car and give the mity vac a couple of pumps. If the car doesn't shut off right away your valve it dead.

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Did you change the filter when you changed the oil ? If you did, you almost certainly knocked a vac line loose somewhere, or worse, broke one of the connector bits that are inline with the big vac line from the vac pump to the booster. Its got all the little vac lines branching off of it. They get brittle and break easy - can be repaired with jb-weld. check function of vac shut off valve on the back of the ip by sucking on the tube leading to it, should shut right down.

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1996 E300 110,000
1985 300TD 212,000
1980 300D 238,000

The first time I change my Oil I craced off the plastic nipple that goes the the main Vaccum Line. I did not ever realize I leaned on it.

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84 300D, 82 Volvo 244Gl Diesel

This valve is hidden pretty well under that white plastic tranny valve. No, I didn't break any vacuum tubing, and in fact, a while back, I replaced the inline rubber connectors with silicone vacuum tubing both at the shut-off valve and at the white tranny valve above it.

Anyway, after pumping the Mity-Vac about 3-4 times, the engine shut off. I must note, though, that the valve will not hold vacuum - it vents over 2 seconds or so. Is that normal?

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84 300SD - bought in April '06 with 237,000 mi

Now that's very warm outside, I'm having shut-off problems again. On colder days, the car will shut off, and on warm days, I have to shut it off manually.

Transmission is shifting just fine, which tells me that probably it isn't a general vac leak... So is that the shutoff valve then?

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84 300SD - bought in April '06 with 237,000 mi

Or the hose leak is on the actuator side of the switch,

Make sure all lines are hooked up, as Diesel911 mentions.
Check for any oil inside the brown vac line going to the shut off valve, that would be a sign of a failed valve.

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83 SD

84 CD

I have had mine sort of rattle like you describe on shut down. It tries to shut off and almost does, but keeps kicking over. usually a vacuum leak some where. I have a Gremlin some where lerking under the hood, he lets me know he is there about every 6 months or so.

toomany MBZ mentioned about oil inside of the brown line, here is a thread WHUNTER posted about placing a filter in line to give you a heads up if this happens.

www.peachparts.com/shopforum/showthread.php?p=1265296


Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

This is a good idea.

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83 SD

84 CD

If it is not a problem with the Shutoff Valve itself or the Hoses/tubing going to it:
Down by the Steering Wheel Lock behind the Ignition Key there is that actual Valve and the related hoses/tubing that switches the vacuum on and off to the Shutoff Valve.

No one answered if the shutoff was supposed to hold vacuum when using the Mighty Vac or leak off gradually.
My Wife has the Mercedes so I cannot check my working Shutoff Valve to see.

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84 300D, 82 Volvo 244Gl Diesel

I had a failing shut off valve that shut the engine down as soon I hit 10Hg with a mity vac, it was still bad.

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83 SD

84 CD

Same here. It worked but it had a slight delay. The replacement shuts off right away.

I'm not certain if it holds vacuum, but would guess that it should. Afterall, you open the vacuum at the key switchover valve to allow the draw against the shutoff valve. What would preclude complete vacuum loss if the IP valve didn't hold vacuum?

To determine I had a faullty IP valve, I hooked up the mighty-vac with a long silicone line attached to the shutoff valve and started pulling oil up the line. Didn't wait to see if it was going to hold any vacuum - diagnosis was done!

Again, just to reaffirm the wisdom of whunter's filter post. Ended up replacing the key valve and the shut-off valve.

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83 300d - 390k