Recently we moved into the mountain area just outside Yosemite. In the past week or two, the temperature slowly worked its way into the mid 20's. Anything lower than about 45, made it near impossible to start our 83 300SD, which in 50 degree plus weather started immediately. In researching the glow plug system, I found out that the relay has a sensor that determines the air temperature and controls the time that the glow plugs have juice sent to them. In the past I would go through 2 or 3 complete cycles to try and fire it up. In checking my plugs I found some out of specs and some dead.

I changed them with Bosch units and now no matter what the temperature is, (been as low as 24) as soon as the light on the dash goes out, I turn the ignition key and within 2 seconds it is purring. I didn’t ream or do anything special….just replaced the 5 glow plugs.

Don

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1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it