Glow Plugs - replace singles or all?

[jcork]

I have had several folks suggest that you test and replace them individually as they fail. Their logic is they are electrical devices and their failure rate is completely random.

I was thinking that you'd want to replace all at once because, they would all operate at a different resistance and the loads between them would be unbalanced, stressing some more than others.

Opinions?

[ford diesel]

I have done it both ways. I was doing them individually for years until i started having some issueswith the wiring from the Starter solenoid to the GP solenoid. (melted at connection. Not sure if this was age or changeing one at a time. I had about 300 k mile on the truck so i did all of them at once, I used the more expensive ones (Bosch maybe, someone help me out here). i eliminated the 2 wires between the solenoids and went back in with a 4 gauge battery cable with 14 amp Fuseable links at the start solenoid. truck now has 486k miles and starts right up even 30° weather.

[ford diesel]

" i eliminated the 2 wires between the solenoids and went back in with a 4 gauge battery cable with 14 amp Fuseable links at the start solenoid"

that actually that was two 14 amp Fusable link,