OK, had a go at live testing the plugs this morning...
Removed valve cover and unplugged glow plugs. Cleaned oil out of the electrical plugs and also found two of the wires had nicks in the insulation, so sealed these with self amalgamating tape - see photo of nick in wire.
Checked resistance of each glow plug between the hex' and the tip which connects to the plug - all reading 0.9 - 1.3 ohms. NOTE: Had to press hard with the meter probes, as the initial reading was about 35 ohms.
Plugged all the glow plugs in and laid an 18" extension bar across the valve rocker to create an earth. Rested the hex' of the glow plugs on the extension bar to earth the glow plugs, then turned the ignition on - none of the plugs glowed.
Cleaned out the electrical plugs which connect to the glow plug tips, then checked the voltage at each electrical plug when the ignition was turned on. Initial voltage is 12v for approx' 1 - 2 seconds, dropping down to 7v for another second, then down to between 5 & 5.5v constant. All electrical plugs read the same.
Then tried connecting the glow plugs again, earthed through the extension bar touching the engine, and they worked OK - see pic of two of them glowing. Careful if you do this not to grab the end of the glow plug when unplugging them again - it's just been up to around 1600degC.
Put everything back together and it started fairly slowly - probably due to me messing on with the glow plug testing over and over again and draining the battery a touch. Will feedback how it starts on the next cold morning.
Not convinced the electrical plugs give the tightest connection onto the glow plugs themselves, but we'll see how we get on.
