Bladehauler
Gold Member
I was replacing the glowplugs in a small perkins( napa crossed the #s off the old 1s over to ngk ) but testing them , i use a ohm meter or a test light, whichever is handy , separate the bussbar off the glowplugs , check resistance from the center conductor to ground. or use your test light ( I clip my alligator clip to the positive terminal of the battery ) then probe the center terminal of each plug. some glowplugs will light your test light dimmly while others not at all. they never seem to fail the same. anyway , no light or little light is usually the bad 1.