Hello,
I have been trying to chase a cold start problem recently and ruled out the glow plugs after I had tested them twice - the only catch is that I tested them when they were semi- warm.
I am not too good with electrical stuff, but as most of you know I'm sure, weak electrical components really show their a$$ when the temp gets low.
I decided to check my glow plugs, which are about 1 year old and 30k miles, when the car was stone cold and found three of them to be bad showing infinity. I warmed them when I took them out in front of a heater to about 110 degrees f and found them to be within acceptable limits. I then put them in the freezer and tested them again and they tested bad.
I know most of you probably knew this, but for some guys like me who rule them out after checking them once, my recommendation would be to check them under the same exact parameters in which they are being called upon to perform - ice cold.
Thanks, Adam Bush

How did you check your glow plugs? Do you have to turn on the ignition? Thanks...

You should check each plug while installed to first see if it's getting power with the glow light on. I get approx 11.3 at each of my glow plugs when she's glowing., but that test is to first check power to the plug only.
Next you have to get an OHM meter to check the resistance on each plug. I read that they should be between 1.7 and 3 OHMs each. Is this right anyone?
I know that if they are bad they will not show any resistance and just show infinity, as if you weren't touching them at all. Luckily, they are cheap, so I got replacements at AutoZone for 11.00 each and now she fires up at 30degrees f running 100% soy biodiesel with some DFS additive.
CYA,
Adam

Adam:

The new bosch glowplugs I have sitting on the window ledge waiting installation on my Volvo are 0.6 ohm each. 3 ohm is probably too high.

Hard to check, takes a couple seconds for my digital ohm meter to respond.

A glowplug that shows infinity cold very likely has the filament detached from the tip, and if it does heat, it will heat the side of the "point" rather than the tip. Pretty much useless.

You can tell by looking at them -- a neat little hole in the tip means the weld failed. A blister on the side of the tip means the filament is grounding on the side rather than the tip.

I only use Bosch glowplugs these days, and the Volvo eates them, too. Champions burned out in a couple years.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I check mine cold, should be close to the same as putting the leads (+,-) leads together on the digital volt/ohm meter.
I have been using Autolite glow plugs, they are cheaper and come with the nut and washer on them. I seem to loose those little things, and go to la la land, darned if I can find them.
They last about 2yrs., I just change them out 1 at a time when one goes bad.
If bosch had the nuts & washers I'd use them.