Glowplug Wiring

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Originally Posted by Jojo

Mate,
you were right, of course! No idea, how I could overlook the obvious. Probably got confused by the fact that I could not find a relay. Anyway, no need to convert, thanks for that. Still some problem solving required as there are only 10.6V at the plug terminals. Maybe this can contribute to the starting trouble? I'll put in new plugs next, could be the easy way to solve the problem.
Cheers

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Glow plugs pull a decent amount of current, so with 4 of them going they may well pull the supply voltage down that low and still be working perfectly.
Have you tried pulling the plugs out and testing them on the bench?

Steve

Quote:

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Originally Posted by Jojo

Mate,
you were right, of course! No idea, how I could overlook the obvious. Probably got confused by the fact that I could not find a relay. Anyway, no need to convert, thanks for that. Still some problem solving required as there are only 10.6V at the plug terminals. Maybe this can contribute to the starting trouble? I'll put in new plugs next, could be the easy way to solve the problem.
Cheers

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sounds about right. they pull about 80 amps and there is either a current limiting sized bit of wire or a resistor in the system (depending on build spec of the rest of the vehicle) it should have a relay or if its direct power a dirty great push button switch,.

what colours your smoke on startup?

does the smoke disipate instantly once the engine is at revs and under load?

Quote:

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Originally Posted by Blknight.aus

sounds about right. they pull about 80 amps and there is either a current limiting sized bit of wire or a resistor in the system (depending on build spec of the rest of the vehicle) it should have a relay or if its direct power a dirty great push button switch,.

what colours your smoke on startup?

does the smoke disipate instantly once the engine is at revs and under load?

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Thanks, Dave! Haven't found the resistor yet and the plugs are activated by turning the key to the corresponding position.
The smoke on start-up is whitish grey (I reckon it is unburnt fuel) and dissipates after a short period of driving/revving the engine, but not instantly.

Quote:

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Originally Posted by steveG

Glow plugs pull a decent amount of current, so with 4 of them going they may well pull the supply voltage down that low and still be working perfectly.
Have you tried pulling the plugs out and testing them on the bench?

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Thanks, Steve! Yep, I had the plugs out before fitting the engine. They did work, but they are, well, aged. I ordered a set of new ones that will go in as soon as they arrive on my premises.


I found out the truck starts easier if I don't touch the accelerator (somewhat of a misnomer in this kind of vehicle) when running the starter in comparison to pressing it down a bit. Over-fueling maybe? But in a Diesel??

Whit smoke on startup is fuel being completely unburnt. Low compression, bad injection spray or retarded timing.

Check the timing first. A bit advanced from the pin is usually good. Then check the inectors.

Thanks for all your advice, folks! I have changed the glow plugs and now it starts with minimal waiting time (about 15 sec) and only a few cranks of the starter motor.
Compression was checked recently and turned out to be alright, only one cylinder (3) had somewhat lower pressure values, but well within the tolerances. Will check the timing next (but now the gearbox is giving me headache).
Cheers