1987 300D Turbo.

I had my plugs changed in December 2005. That winter the glow plug light would occationly not light up (25% of the time) until I recycled the key switch from On to Off position about 2-4 times (depending how it was feeling). Then the light came on, heated the plugs, and off it went.

Then came spring and summer 2006, and I never had this occurance. Now this winter the same thing happens.

Any ideas? Thanks.

bad temp sensor in the GP relay? bad GP relay? bad Glow plugs? Dieselgiant's website is great with the GP diagnostic procedures.
John

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Start here:
http://www.dieselgiant.com/glowplugrepair.htm

The light means relatively little. (Although no light is generally an indication of something bad.)

The timer on the relay will run for 30ish seconds (36 on my 87 300D). The glow plugs are on and heating for the whole 36 seconds as long as I do not turn the key to start. My light goes off after 6 seconds. The light is not really all that important. If it is quiet you can hear the relay release at 30ish seconds. You can also turn on the dome light before you turn the key. It will dim when you turn to glow. After 30ish seconds it will brighten back up.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.

I have the same engine you do, and mine does the exact same thing. The problem is that the relay is probably on its way out. Mine works intermittently in cold weather - about one start out of six for me, I turn the switch on and the light doesn't come on - and it is definitely NOT glowing during that time.

My solution? Turn the switch off, raise the hood, take the Mag-Lite out of the door pocket, whack the glowplug relay solidly, (one tap is enough, nice hard tap) - close the hood, and the light (and the plugs) work the next time I turn the key on.

Relay is sticking off, and may fail. I'm still waiting on mine to die completely; it's been doing this for two winters.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL