Is it not normal for them to turn black?
Do they still get hot when you hook them up to power?
Have you measured the voltage at them when they are on to see if it is normal?
Quote from: "jimfoo"Have you measured the voltage at them when they are on to see if it is normal?No, I haven't... hmmNow, here's something else a bit different in my setup... each plug has a heavy individual wire going to it. Makes it much easier to pinpoint which plug is dead. I've used the same setup in all my diesels and never had a problem, and I can't imagine it would cause this problem.
Over torquing when installing them can have very detrimental effect on their lifespan because it compresses the resistive element... don't have my Bentley handy but I've read in several sources not to overdo it... something to check with a torque wrench the next time you are changing them perhaps ??Vince