Glow plugs (underpowered battery??)

[g8dhe]

I noticed when testing them that they all had differing times to 'glowing'. I'd read in the service manual that there is a resistance of about 5 ohms through a healthy glow plug - I tested mine whilst they were out and some were as low as 2 ohms. I know once failed they have no circuit through them -does anyone know if the resistance value changes as they wear out?.

Have a look at this NGK article, I notice that someone mentioned that the NGK 701 J was a suitable type for the Bongo (I've no idea as run a V6) this is quoted as being a Double Coil, Self Regulating which takes 4 secs to reach temperature, they suggest that the resistance should be below 1Ω and will increase with age, until it finally blows - infinite resistance!