All;

Any idea what could be causing my Cali-spec 1985 300TD to not want to shut off when the ambient temperature is 40 or below? At temperatures above that, shutoff occurs immediately as the key is turned, but if it is cold outside, the car will run on for 30 seconds or more, with the revs slowing and finally stopping.

Haven't had a chance to put a Mity-Vac on it yet, likely that will be this weekend's project, but I can't imagine what in the system could be affected by temperature...

Thanks in advance

r/
Dave

Probably a vacuum leak at one of the rubber vacuum line connectors. Cold temperatures will tend to make the rubber hard and more leaky if it is marginal. Start by looking at all the vacuum connectors under the hood.

You have a vacuum leak somewhere. The rubber fittings get harder when it is cold causing a faster leak. Get your mighty vac out and get testing!

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

The Climate Control (Klima) is effected by temperature......so if one of the diaphragms is leaking....it could possibly cause a similar symptom......

SB

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Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG

I would think the vacuum leak afecting the shutoff is just afecting your climate control as well when cold out. Wherever it is. If vacuum is disconected from the climate system when off it may be an indicator of where the leak may be. For all I know the climate system could be under constant vacuum though.
You could quick test that by seeing how the car shuts down cold perhaps with the climate control off. Temporarily plugging a line might give separation as well. Really though your mity vac should quickly give some indication of where the leak or leaks are at cold temperatures. You unfortunatly have to do these tests out in the cold.

Shorebilly has it. Try pushing the far right climate control button before shutting off in cold weather. If it shut off fine, you've got a vacuum leak in the climate control, probably a bad pod. Could be the footwell pod. If you have the system set on automatic, that footwell pod will activate when the heat turns on. could be others also.

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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

We all know that diesels don't like the cold, below 40 your baby wan't to keep warm by continuing her idle,,,

As far as leaky rubber vacuum connectors, wouldn't a little vegetable oil soften up the rubber? It sure does on the rubber stoppers that prevent the fuel door from having metal on metal contact. softens those puppies right up.

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It could also gum up the vacuum system. Those rubber connectors are cheep.

__________________
1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine