Posting this more for verification on my part...

Lately the glow plug indicator light on my dash has taken shorter and shorter amounts of time before going out. This is of course now that it is getting colder and colder.This morning, a 36*F morning, the GP's stayed on for only about 10 seconds. I had longer times than this during the summer.

So I think it's the GPC. BUT... the other symptom is that when I turn the ignition key to start my radio doesn't always cut out. So I'm wondering if that's an ignition switch issue. Of course they could be unrelated too.

I'm also wondering about sources of the "Bosch Duraterm Mercedes-Benz Fast glow kit for Diesel cars". The thread below lists ******** Arizona but I've never heard of them before.

http://www.peachparts.com/shopforum/showthread.php?t=122555

Thanks,
Bill

It doe's sound suspicious that your radio doesn't have it's power cut offf in "start" position. Sounds like a short within the ignition. As to the glow plug light staying on for shorter times in cold temps than warm temps, there are probably a number of things that could be going on. If you have a lamp on your panel that lights when the emergency brakes is on: set the emergency brake on so you can see the light. Now activate the glow plugs, the emerg brake lite indicator should dim. As long as the indicator is dimmed, that is the length of your "real" glow period. I am not familiar with your model, but I am not altogether certain that the glow plugs are not still glowing for some period after the indicator light goes off. The emerg brake lite idea I brought up is fast and easy, might help, might not, but certainly worth trying. If there is a real problem needing fixing you're probably looking at testing the glow plug relay. Do a forum search, there are a lot of threads outlining this circuit, how to test, how to replace. I still have this troubled feeling that you might have a primary problem within the ignition module due to the accessorie's not turning off. Are there any other accessorie's such as the blower motor that don't turn off in "start" position?

Just because that light's off doesn't mean the GP's are off. That light is just a guideline. If you stick your head out of the car when you turn the key on, so you don't hear the noise of the key turning, you can hear the relay energize. It makes the same clicking noise when they turn off. The time varies depending on the engine temp but they are definately on longer than that light. I always let mine go a few seconds longer than the light, even in warm weather.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

I can't hear the relay turning off at all. However testing out my GP's I can see serious voltage drop from one to the next. First one gets almost 11V, then it drops to 8 for the next, then 5V... by the time I get to the last GP it is receiving less than 1V.

I think I'll just put in that new Bosch style relay anyway, along with 5 new GP's. They're cheap enough that it doesn't seem worthwhile fooling around.

Bill

The description above is normal operation for a car with the big series loop plugs instead of the parallel pencil plugs.
You will need the special large thread pencil plugs and you will need to rewire for parallel if you want to convert from series to parallel.

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'79 300SD W116
'86 190E 2.3-16V W201
'92 300D 2.5 W124
'99 E320 4MATIC S210

All my glow plugs test ok, but the light goes off after about 2 seconds, tops. I just wait about ten seconds and turn the key. If you open the hood and turn the key to the glow cycle, get out and listen, you should hear it click off in about 40 seconds I think.

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B
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1983 300SD