Sounds like you are doing something wrong. Ground your negative lead although it does not mater if it is the negative or positive lead. Touch the other lead to some other grounded point. Or touch the two meter leads together and mention on site what is indicated. Might be a start for others to help. It is still the easiest way to identify burnt out plugs usually.

Just bought some 12 gauge wire to extend my negative lead to the battery. Will go test with that solid ground tomorrow.

When I touch the leads together the meter jumps around, finally oscillating between .1 and .3. It never settles on a value.

This isn't rocket science, so I'm wondering what is going on....

__________________
JBG
1985 TD wagon, 228k
running on grease since 3.07
AUSTIN, TEXAS

Is your multimeter working correctly? Is the multimeter battery new? Test for volts at the battery to make sure your leads are good.

John

__________________
Certified Registered Nurse Anesthetist (CRNA)
2002 F250 powerstroke with Plantdrive WVO conversion
1983 300SD 190K miles ,sold
2006 E320 CDI

Sounds like the meter is not perfect. Or it's battery is low. Still good enough for your test though. It could be intermitent leads or oxidized plugs but think not as the given values are pretty close.
Anyways consider the oscillation as a meter problem for practical purposes. You are looking for low values on each plug. Usually a burnt out plug will be wide open. You still might notice a plug with increased resistance . The oscillation range should vary if there but at slightly higher values when it settles down.
As you say not rocket science but confusing to some exrent depending on amount of experience using a meter. Usually the worst problem reading things is getting good clean connections with no oxidation on your points of contact.

If you touch the probes together you should get a steady zero, or close to it. Do you by chance have it set on voltage? That'll give you funny readings if there's no voltage. Also if you meter doesn't auto-range, make sure you have it on the right range...you're only measuring 1 Ohm. Just for fun, get a light bulb and put one lead on the metal tip and the other lead on the threads, that'll give you some resistance.

If you can get your hands down by a plug, but one probe on the back end where the wire connects, and the other probe on the engine block (anything big and metal on the car can be a ground) or on the body of the plug. That will directly measure the resistance across the plug.

Then check the wires, one probe on each end of the glow plug wire.

Good luck

__________________
1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

............the digital multi-meter strikes another innocent victim.........yet again.

If I ever decide to buy one of them..........please shoot me.

Carlton, you use an analog one? I just bought this POS on Saturday from Radio Shack so I'll just go return it, no big deal. When I put the leads together they jump between .1 and .3 for about 10 seconds, then zero out. Should it just always be at zero, no questions asked?

It measured the battery fine at 12.73 volts, so I'm thinking the meter should be ok....but when I'm on Ohms at the "200" dial mark--which is where the Haynes manual says to go, and where it is on Diesel Giant's tutorial on glow plugs--I can't seem to get the ground situation sorted out. I touched the negative lead all over the engine metal, various bolts, etc., and got no reading on the glow plug ports.

Anyway, I'll give it a shot with the jerry rigged piece of wire connecting to the negative battery terminal tomorrow.

The car cranks like a bastard and barely turns over after sitting for a cold night. Something's up.

Again, what tools do you guys use to remove the actual glow plugs?

How often do you have to replace glow plugs living in a relatively cold climate?

Thanks

__________________
JBG
1985 TD wagon, 228k
running on grease since 3.07
AUSTIN, TEXAS

I have a $10 Radio Shack analog meter (cigrarette pack size) that does 99% of my troubleshooting. It cannot measure 1 ohm, so I use the $50 analog meter for that. The $50. meter gets used once every two years.........if that.

I don't comment on the function of digital meters. Too many folks have gotten way too confused by their displays and their questionable accuracy and repeatability. This might be due to the fact that they are low cost meters.........

An actual wrench is needed for actual glow plugs. You can remove imaginary glow plugs with anything you like. When I am in hurry, I just call Snow White and have her send over five of her best dwarfs.