I'm at school now, but when I arrived here a few minutes ago, the 1982 300D would not shut off when I removed the key, so, I had to open the hood and shut it off manually. Is this a vacuum problem? I suspect that it might be because the other 3 door locks did not unlock this morning with the driver's side lock. BTW- It may be unrelated, but the GP light failed to come on this morning, it's working intermittenly, some days it will come on, others it wont.
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

get under the hood and start replacing the 3-way and 4-way rubber connectors, replace the yellow check valve at the firewall, and all other various and sundry rubber connectors(you can just cut these to length from vac hose). Replace all this stuff if it hasn't been replaced yet, the rubber swells a little(it may not be obvious) and cracks a little bit, which causes leaks. It's cheap so just go ahead and replace this stuff willy nilly if you haven't before. Use a mity vac thereafter on your main vac pump, fuel shutoff valve, brake booster, door locks, etc. You'll find the problem eventually.

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)

Great advice. It was probably a little bit colder yesterday and the vacuum leak surfaced causing the dieseling. Let us know when you resolve the issue...

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1985 300 D T - Rauchsilber (Smoke Sliver Metallic) with MB Tex Quartz 155 = Cream interior - 320K and counting!

1999 E300 TD - Silver - Just got her 3-13-15 !

the 2nd '83 300SD - Brown Metallic - traded away

1985 Limo Diesel aka "Stretchy" - Sliver - Blue Int - Sold but still in Athens

1983 300SD - Brown Metallic - Sold April 2008

1982 300 D T - Royal Blue with Tan interior - Sold

shutoff is vacuum problem for sure, the glow plug issue is separate - check continuity from each lug on harneess at glow plug relay to engine ground. Each should be less than 1 ohm. 1 or 2 bad plugs will cause the light to be intermittent

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

The source of my vac leak is inside the DASH. An ACC vac pod, no less, or perhaps a tertiary rubber connector. That figures, I have the WORST LUCK of anyone in the entire western hemisphere. Dude put a check valve in there to serve as a temp fix, to spare my wallet for the time being.
I know pulling the dash to work on this stuff is everyone's least favorite job on these cars.

onward

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)

Yep, it's a vacuum problem, let me tell you about this morning. Same routine, had to open trunk with key, I started it up, and turned it off to see if it was still "dieseling". It "dieseled" for about 10 seconds, and shut off. I started it back up, and drove on to school. I noticed as I drove on that the other door locks were now unlocked since I did not lock the driver's side door when I started up, so I hit my door lock, and the others went down as well. I pulled into a space, and shut it off, and it shut off normally. It's been colder than usual lately, in the 60's, and I am not looking foward to Friday morning! The low Thursday night is supposed to be 48!!
I'm not going to touch this car, me and DIY projects are not very good friends, I'll leave this to my indy.
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

When I purchased my MB a couple weeks ago, It had all the original books and manuals with it. I thought it was interesting that the owners manual devotes a section to manual shut off......like it's inevitable. I haven't had to use it yet..........knock on ...iron?

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83 300TD

I bought my '76 300D through E-Bay over a month ago. I had sent my best friend to Ontario to drive it back for me, and he claimed that during this 1200 mile trip, 9 times out of 10, it would not shut off right away. Yet, in my entire time of ownership, this has not happened to me even once, UNTIL LAST NIGHT. I had driven my wife to a 2 hour meeting and had some time to kill, so after doing a couple of things, I bought a magazine and drove back to parking lot of building she was meeting in. Because I planned to sit in car and read, I locked my driver's door, then shut the car off- but it just kept running for about 10 seconds. HMMM... I says- then proceeded to read. Wife came out, I unlocked her door and started the car. Off we went, and when we got onto the highway, I noticed my cruise control was acting funny- the car would not maintain speed, but it was not as if the cruise was completely off either- I found that it would loose a lot of speed up hills, but as soon as I stepped on accelerator, it would kick in and resume. Finally, when we got home, I shut the car off, and again it ran on for about 10 seconds. Then it occurred to me that my door was still locked- I never had driven car with driver door locked before, so I unlocked it, started car and then shut it off. It stopped immediately. Then, it all came together in my head so I started up again and headed for the highway- cruise worked perfectly now, then I locked the door and it started acting strange again.

Now I'm certain of where my vacuum leak is- obviously in the doors. I kind of suspected door vacuum was weak anyway, because they all lock OK, including trunk, when you leave the car, but when you come back, only the driver door unlocks with key, then the rest pop up several minutes after the engine has been running.

Now what I don't understand is what does vacuum have to do with cruise control? I always thought cruise was a totally electrically operated function.

Dave Milton

'76 300D White W115 "Pearl", with 140,000 Miles

Until you can troubleshoot the vacuum system, lock the driver's door when you shut off the car. Locking the driver's door shuts off the balance of the locking system. This helps you shut the car off easily until you get it fixed.

BTW, your mechanic can fix it, but it could turn into the most amazing combination of high cost service hours and low cost part you have ever seen. It could be as simple as a line with a crack in it or a door lock mechanism with a cracked diaphram.

All I know is everytime I repaired a leak in the door lock system the part cost nothing, but it sure took me a long time to troubleshoot.

I say, get a MityVac and a 12 pack and do it this Saturday while you listen to the Yankees beat the RedSox.

JCD

The amplifier under the dash is electronic, but the actuator in the engine bay is vacuum operated. They went to an electronic actuator around 1981 or 82.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

This morning when I got to town (20 min. ride) in my '80 300 TD, I noticed it took more than the usual pressure on the brake pedal to stop at a stop sign, and each stop after that. When I parked and turned off the key, the engine didn't stop. The stop lever works all right IF the idle is adjusted all the way down. I've started looking for vacuum leaks, and it looks like this might be a good time to learn to use the Mityvac I bought last month.
Is vacuum used to boost braking? I found this thread by searching for "motor won't stop" and now plan to search something like "brake boost."
Any other suggestions?

Yes, vacuum is used for both brake assist and engine shutoff. You've got a bad vacuum leak or a busted pump. We just went around that tree here.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

is there a way to shut off the vacuum to the locks all together? my power locks have never worked, but i futzed with them the other day and now i'm having dieseling problems like whoa. it's obviously something in the back doors, and i was hoping i could just clamp it or something. is that possible? where should i do it?

thanks,

nick

You didn't tell us what model and year you have, but you should be able to disconnect and plug the vacuum line to the door locks under the hood.

This could be the key to your problem. Do you have the heater controls in a different position than on previous days? If so, you could have a leak in a climate control line or pod that is bleeding off enough vacuum to make shut down difficult. To test this hypothesis, push the far right button on the climate control to shut everything off (if I have your year and model correct?), let the car run for a while to build up vacuum, then try shutting off the engine.

You should be able to plug the back doors under the rug by the front seat either just on the driver's side or possibly on both sides, although it's easier to plug the whole door system under the hood.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13