Glow Plugs - Timoshanko
Is there a DIY method to test a diesel engine glow plug for failure I take it they must be removed from the engine block for this
Glow Plugs - mal
Although I am not a techy expert I will add my contribution for what it's worth .
The only time I had a diesel my glow plugs were checked simply by removing them and connecting them to a battery for a moment simply to see if the glowed.
Glow Plugs - 156v6
If you have a multi-meter you can give them an easy test - take off the lead to the plug, and test for resistance between where the lead was and the base of the plug. Should be almost no resistance at all. Not a 100% test for being OK, but if resistance is high the they're definitely had it.
Glow Plugs - Chris TD
Got to try this tonight as the Astra has decided to become reluctant to start (maybe it's got a cold - the rest of the family have!)

Do they actually glow red hot (visible to the eye) or just become F(airly) hot? (detectable by the gloved hand, or ungloved hand accompanied by numerous expletives?)

Chris TD
"Must add plasters to Toolkit"
Glow Plugs - 547HEW
They should glow red hot if tested outside the engine. Possibly even hotter than red hot. But they are internally thermally regulated (at least the Beru ones are) so as not to burn out prematurely.

Glow Plugs - Dizzy {P}
I'm not sure that *all* BERU glow plugs are internally regulated. Certainly those that operate without a separate control (ECU or black box) are self-regulating and they stay on all the time that the engine is running.

BERU self-regulation is by the use of two coils in series. The tip coil heats to the required temperature and the electrical resistance *decreases* with the rise in temperature as is normal. However there is a second 'control' coil just behind the tip coil made of a special material which *increases* in electrical resistance as it is heated up by the tip coil and therefore regulates tip coil temperature by regulating the current flow to it.

I would take care not to leave even the self-regulating glow plugs on for too long in the open air because they will be seeing a larger temperature difference than when they are in a running engine and this might cook the coils.

These superb self-regulating glow plugs have been around for over 20 years, BERU's patents on them having only just expired. I imagine that the dreaded cost-cutting stopped them being used universally.
Glow Plugs - Peter D
Good advice Dizzy, The some of the plugs have an inherent PTC Resistor ( Positive Temperature Coeffient ) tesistor which due to the metal work heat sink effect remains initially cool compared to the low resistance heater element 1 to 2 ohms. As the PTC resister heats it it rapidly increases in resistance and shuts the glow plug down. And yes to test them in the car apply a test meter and they should be very low resistance 1 to 2 ohms when cold If toy have a high current range on your meter you could power them up one at a time straight from the battery with the meter in circuit at least a 10 amp range. Initially you will see a high current and within 10 seconds you should see this fall off quite rapidly. Regards Peter.

Value my car