Glowplug advice?

muzz67, Oct 13, 8:00am
Dont seem to be working at all, although 1KZt starts fine in summer.
Tester shows 11.5v along bar, but consistently, not turning off after a few seconds.
Removed 1 glowplug, dead as a dried out dingo.
Assume gp timer should stop power to gp's has failed causing the gp's to fail?
cheers.

happylad3, Oct 13, 8:25am
Wouldn't think so. Depending on the temperature etc. Some glow plug systems can run for up to a minute on a frosty morning etc.

Turn the key on, and time how long the rail had power for. Could be 90 sec or so.

gpg58, Oct 13, 8:43am
It is possible to see some voltage with a modern digital meter, even on what for useful purposes, is actually dead, (tru burnt out relay contacts, or sometimes a loose fuse). So to prove you actually have power being supplied, you would need to put a decent load on it, like a bulb etc

i haven't read thru it but google found this manual.

http://htftp.offroadsz.com/marinhaker/programi/VSI4KO%20ZA%20TOYO/Land_Cruiser_1996_Electrical_Wiring_Diagram1.pdf

intrade, Oct 13, 8:54am
how did you test the glow plug exactly and what is the volt written on the plug?

tweake, Oct 13, 10:51am
1kz needs glows to be replaced regular as they break off.

by mem they are ceramic and will glows untill engine is up to a certain temp. all controlled by ecu.
can't remember if they are a dual voltage, i suspect they use full voltage all the time.
need to test their resistance. a high rail voltage means glows are not working and not dragging voltage down.

franc123, Oct 13, 10:58am
Some systems won't switch off at the same time as the glow lamp, you need to find out how long its supposed to be energizing the strip for, for any given engine temp. Carbon buildup around the plugs is a common reason they die.

mrsglaucoma11, Oct 13, 11:27pm
Had a Prado with the 1kzt. Ate glow plugs every 30-40 ks. No one could figure out why?

intrade, Oct 14, 1:03am
there is a few reasons but knowing how the system works would be the first thing to learn.
someone said ceramic and computer controlled
ceramic plugs are dead if dropped from 10 cm on to a concreet floor.
also computer controlled would mean its duty cycle controlled means its pules on off , a good fast oscilloscope would graph a square wave about the controll of it .
also faulty injector spray pattern can premature destroy glow plugs when the spray pattern is directed wrongly due to wear at the redhot glowplug thermally shocking it and shortening its livespan each time it happens.
these are a few things only
I fitted shorter nissan glowplugs on my fiat as it was nuking the glowplug every few month and i know it has shot injectors , so i scrached my head why the shorter ones dont fail.
well the spray pattern is most likely now blasting past and not thermally shocking them no more, is the logical answer.

tweake, Oct 14, 3:37am
i don't think 1kz has PWM glows. simply on full time i think. (sorry i'm more the earlier L series than 1kz). can't recall 1kz having dual stage.

1kz are IDI so how the injector sprays fuel around the glow would have a lot to do with its lifespan. metal glows you can see where they have eroded.
the other thing is water temp sensor may be faulty (glows running to long) and quite often the ecu caps fail causing all sorts of gremlins.

tweake, Oct 14, 3:46am
looks i have the manual here.
no 2nd voltage system. so its full voltage.
light on the dash does vary with temp, but not about glow time. it shows how long you need to wait due to engine temp. really only changes when its below 0c at -20c its 3.5 sec and at 0c its 1 sec.
glows are on until engine reaches about 50c.

of interest it has a carbon cleaning process to clean the glow area out.
possibly they get a build up of carbon in the chamber. that could hold heat in and make the glows hotter than what they are really designed for.
put 200ml of cheap mineral 2 stroke oil in a tank of diesel. that usually cleans out a lot of the carbon.

muzz67, Oct 14, 4:14am
Thanks for the help folks,,
The old girl runs really well, 265000km so far.
Took a couple of second winding on frosty mornings,, all good now tho.
Took 1 plug out, got a blackened tip, not scaly.
Got 11v marked on them.
Tested by putting it across an older battery with about 11-12v in it for about 2 seconds, but did not get even slightly warm.

tweake, Oct 14, 4:18am
you may have a couple dead glows.
just replace the whole lot as set.

intrade, Feb 12, 2:17am
if it is not a pwm glowplug that test is fine if it is a pwm plug then it would destroy even if you hold it just for 2 full secounds on a continues supply, so be awear of that practice not to be used on modern diesel with on off pulsing noumerous times a secound .