Intermittent Glow Plugs

[abarhum]

Glow plugs on my L3600 operate only intermittently. The glow plugs themselves are good. I replaced the relay and it made no difference. What should I look for now? I have power to the relay and it should send power out of the relay it doesn't do it. But I don't uinderstand how it all operates and I need some help!

 

[PILOON]

Glow plugs draw lots of amps.
Essentially they are resisters that glow when shorted.
The contacts need to be A-1, clean or burnish to assure good conductivity.
While voltage can sometimes be read amperage will not occur on a week contact.
Grounds are probably OK otherwise starter would not turn, however there is always the chance that a frame ground could be a culprit, so check that as well.

Is the culprit the key switch? spray a cleaner into the guts of it. (I often use WD40)
There might be corrosion inside the switch.
(My own switch was all gunk ed with green corrosion inside, WD40 'got her going')

High current switches, by design, need heavy brass contacts, which in turn want to turn green with corrosion. Just the nature of the beast.
As grease dries up it becomes an insulator rather than a lubricant.

Same for relay, contacts and ground.

Good luck, you'll get her going.

 

[GT2]

My L35 does the same thing!
The owners manual says It senses the temp and decides weather to turn on the pre-heat or not?
But I have started it cold with the pre-heat not coming on and then later after warmed up it will restart with the pre-heat coming on?
Think I will look at the key switch.

 

[MMH]

Glow plugs draw lots of amps.
Essentially they are resisters that glow when shorted.
The contacts need to be A-1, clean or burnish to assure good conductivity.
While voltage can sometimes be read amperage will not occur on a week contact.
Grounds are probably OK otherwise starter would not turn, however there is always the chance that a frame ground could be a culprit, so check that as well.

Is the culprit the key switch? spray a cleaner into the guts of it. (I often use WD40)
There might be corrosion inside the switch.
(My own switch was all gunk ed with green corrosion inside, WD40 'got her going')

High current switches, by design, need heavy brass contacts, which in turn want to turn green with corrosion. Just the nature of the beast.
As grease dries up it becomes an insulator rather than a lubricant.

Same for relay, contacts and ground.

Good luck, you'll get her going.

Good points. Being up in Canada I'm sure 100% proper GP operation is more important for you than many of us.