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Discussion Starter #1
does anybody know the cold resistance value for glowplugs ?

I am trying to determine if I have any faulty glowplugs in my 87 300d W124

-Jason
 

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I don't think there are specs for it. I was just reading some MB service information, it just says replace if it has an open circuit. But it does say that they should draw 8-15 amps. So if you use Ohms law, with a 12 volt system, I guess it should be somewhere around 0.8-1.5 ohms.
 

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Discussion Starter #3
I am getting 38.9 ohms on all plugs

so I dont think they are ALL bad.

but I have a strange cold starting problem.
the glow plug relay seems to be working.. it provides 12V to all plugs
for what seems to be the priper amount of time, but in order to get it started cold ( I live in FLA so "cold" is outside air temp of about 80F)
I have to glow twice and run the starter for about 10 seconds glow again and give it some accelerator pedal and she starts and run rough for few seconds
then clears up and runs fine. hot starts are no problem.

sure seems like a glow plug system problem to me ..

any ideas anyone ?

its my first OM603/W124

up until this point I have only owned OM617 series engines

-Jason
 

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I'd say try to find an amp clamp, and see how much amperage each plug is drawing. 40 ohms seems a bit high to me, though.
 

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Discussion Starter #5
it was totally the glow plugs..
my mistake testing them thru the wire harness connected to the relay (whisch connects them all together giving the same resistance value)

DOH !

anyway most of the plugs were completley bad with only two marginal.

so after the PITA job of replacing the glow plugs
starts right up.
 
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