[Vwdiesel] Slowing death of Glowplugs

Val Christian val at swamps.roc.ny.us
Thu Dec 30 18:53:42 EST 2004

I would not really want to reduce the voltage to the glow plugs,
as that will impact starting efficiency.  Since the temperature
vs. time curve on the GP is rather long, it might be better
to heat quickly, for shorter, than slowly for longer times.
Not only for efficiency, but also for GP life (other problems 
can include bonding problems, insulation failures, etc.).

As for Hagar's concern about life...the laws which apply to 
incandescent lights, also apply to resistive heaters.

Enduring upstate NY winters, I'd rather have 13V sitting on my 
glowplugs some cold morning, rather than 10.3 or 10.7 volts.
Think twice about reducing voltage.

As far as I know, glow plugs on A1 and A2 IDI engines are not
run after the starter engages.  That's a function of the glowplug
relay.  The relay gets a signal from the starter, which stops the
glow cycle.  If the GPs come on after the starter signal,
without a power-off of the ignition, then there is a failure
in the relay.  This used to happen often on A1s, for two
common reasons: infant mortality and water-induced failure.

I've never had a glowplug fail the same season, except when 
there was an injector or runaway oil ingestion problem.
If your injectors, and the glowplug power system works OK,
then the liklihood that even one plug needs changing in two years
is quite small.  GP failures are signs of other things gone


> I think this confirms what I said about the vulnerability of
> the plugs. It also makes me want to set up the passive LED
> system and using the blocking diodes in each GP supply would
> reduce the applied voltage and  power output of each plug.
> Being able to turn off the glow plugs as soon as engine
> starts also helps and this is now incorporated into my
> Quantum.
> Mark(The Miser)UK
> I have had at least one experience where boosting a tired
> diesel in winter
> from a healthy truck with a good alternator resulted in most
> of them going open.
> I suspect the boost (at 13.6v) from the healthy truck, with
> big cables, was
> more than they could take for any length of time.
> Sandy
> Sandy are we dealing with the OLD style plugs ?   if so
> from 11 Volts to 13.6  will
> kill em fast.
> Remember the square LAW ?   double the voltage  gives 4
> times the heat.
> I have no tables for heaters  but Lightbulbs   according to
> Westinghouse goes
> as follows.   Increase voltage from 100   to  108   reduces
> life to  50 %.
> Reduce voltage to 92 Volts     life is increased to 310 %.
> Glowplugs are probably similar to Lights.
> What kills em ?  ---HEAT.          pure and simple.
> Does a glowplug do any good at reduced voltage
>   ---absolutely. Make a step
> down resistor system and have lots of AFTERGLOW.
> Will explain how I did it some other time..    By the Way
> the red wire with 4 white
> stripes ?   ----VW   1980 ?  it is bigger than # 12 but
> smaller than # 10   ---so we
> are looking at slightly more than 1 OHM per 1000 feet.
> VW wire gauges are mm square. ---- way better system than
> that garbage USA wire gauge shit.
> Mark Shepherd what is the standard in the UK ?.
> In Denmark it is square mm  simple to use.  2.5 ?    house
> wiring. For DC just double for
> double amps.   Try that on a USA system ?-.
> USA is a retarded ---- outmoded  STUPID  system. IMHO.
> Brown and Sharpe wire gauge ?
> Bigger number smaller wire ?   go figure.    ---I tried but
> it -- it is still STUPID.
> As you go bigger ?    0    and 00   and 000  and so on ?
> Anyone know of somethig
> dummer ?
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