[Public-list] Why , oh, why won't my glow plugs glow?

[John Boor]

> 
> 
> This is what my VW Diesel mechanic does, is measure the
> current going to the glow plugs. Since all glow plugs are
> in parallel it is easy to isolate which one is not working
> properly. A healthy glow plug draws several "AMPS" but you
> need a fancy high current measuring device to check this.
> 
> Not to scientific a method, sometimes the mechanic takes
> out the glow plugs and connects each one to a battery
> using battery cables and looks to see if they glow well.
>

 By taking out the glow plug and connecting it to a battery
is not a valid load test.  Remember if the engine block is
the negative ( or low ) side of the circuit and you have a
poor connection to the block a small resistance will result
in lowering the voltage right at the glow plug.  To do this
correctly your volt meter positive ( red ) lead must be
right at the plug and the negative (black ) must also be
right at the plug casing, when this is done you should read
12 volts anything less will cause the plug to have lower
heat.

John Boor
MAHSEER #380

 1128002999.0