I am wondering if I should change the glow plugs. They are the original plugs in my 1993 K3500. I have tested them and their resistance is all less than .01 ohms. Do they wear out? I just got the truck, only has 75000 miles on it, but in the cold Wisconsin winters I am wondering if I should change them? Thanks in advance.

If it ain't broke,,,, well you know the rest,,, Does it start fine? ie: no excessive smoke?

supposed to be .8 to 1.2 ohms

well....thats with the .4 my lead wires have...your may be different....

so in reallity mine measured .4 to .8

I've only had it since May, so it hasn't been cold, really. A puff of smoke is all I get after at most 2 seconds of cranking. Really, up to 1.2 ohms? Then mine should be ok? Should I just wait until winter and see what happens?

are u sure your on the right settting? im thinking your on HUNDREDS of ohms

You may be right. I'll check tomorrow. Either way, what do you think?

if they read all 1.0 ohm your set....dont do anything. its if they read over 1.5 ohms when theres a problem.

unless you meter reads 1 without the decimal....thats an open circuit.

You may be right. I'll check tomorrow. Either way, what do you think?


I would probably leave them be.

BUT, it would be nice to replace them now before they rust into the heads anymore. It would be a real good idea to put anti-sieze on the threads of the new ones.

easy to check, put an aftermarket Ammeter in series with each plug. The ammeter should read 15 amps per plug. Ammeter cost around $20.00 ( JC Whitney ect ) I installed two to monitor both banks ( 60 amps/ bank ) Used 8 gauge wire. Be sure to replace with the ( 60G ) plugs as they are far superior to the originals. If the originals test good, keep on truckin.

I'd replace them to take them out of the equation with starting or smoking problems you may have down the road.
15 years is a long time for them IMO.

Thanks for the great advice. I will do the ammeter check. I did pull them all out a couple months ago and put antisieze on the threads. They came out easily anyway though. Wonderful site.