Circuit timer on glow plugs

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ben85

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Just wondering if anyone has done this?

Heard recently that zd30 navaras keep glow plugs on untill engine reaches operating temp, glow plugs get red hot while head is still cold and cause cracking of the head.

Anyone shed any light on this?
 

austingtir

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Just wondering if anyone has done this?

Heard recently that zd30 navaras keep glow plugs on untill engine reaches operating temp, glow plugs get red hot while head is still cold and cause cracking of the head.

Anyone shed any light on this?

I dont own a ZD30 but the wiring and ecu etc etc. is a very similar setup.

Here's a test turn your ignition on with the bonnet open. locate the glow plug relay next to the engine compartment fusebox.... assuming its the same as mine.... and listen to the relay click off. It will be like 20 seconds or something.

No way a glow plug could crack the head not in a million years.

Cracking heads are more likely caused by EGR soot build up causing blocked intake manifold ports causing overheating.
Its also supposed to be a thing where the more heat you put into the head ie chipping with higher cylinder temps due to more fuel the more heat cycles the cylinder head gets put through the more likely it is to crack.
 
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Old.Tony

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^ Agreed. Glow plugs are really just minor heat sources. Even in the D40 they run until the coolant reaches 85C, even if the dash light is out.

To crack the head on a diesel you do need to give the engine some rather special abuse. Running without coolant, hydraulic locking, overboosting - you can overfuel them plenty and won't have a problem except for the amount of soot. Overboosting will dramatically raise the combustion temps closer to the point where the alloy in the head starts to be affected.
 
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Hmmm.

Ill be watching with interest, see if this thread goes anywhere.
Lots of patrol guys doing this I think, and I was wondering when navara boys would get onto it. This may end up being a worthwhile mod.

My theory, and I could be way off, glow plug heats up tiny spot of head and it cracks across the small bit of "meat" between glow plug and valve.
I have seen pics of a few zd30 heads with tiny cracks here.(patrol forum). These cracks were found when motor was pulled apart because of piston failure and probably had nothing to do with it.
Probably doesnt affect anything coz its nowhere near oil or water gallerys.

I even have a spare head in shed, its supposed to have only 88000km on it. Guess what? Its got a tiny hair line crack between glow plug and valve. It would not surprise me if many of them have.
I will post up a pic when I can in a few days.

I am interested to hear more thoughts.
 

tweak'e

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patrol guys where doing it because glows where getting eaten.
that can point to high egt's or injector problems.

havn't heard of it in the navaras, but navaras have less engine failures to.

running glows won't crack the head. when engine is running its only a minor heat source but it gives ignition a starting point so there is reliable ignition untill the engine is fully up to temp.

one thing i don't know is the reliability of the glows. in some of the earlier toyotas the glows are changed every 100,000 as they have a habit of breaking off when they get old. the broken tip then damages the piston/head/bore.
 

Fat801

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I've just started rebuilding zd30 head cracked between exhaust valves pushing air into coolant and blowing out the overflow bottle pistons are cracked but not completely shagged cracks between all valves and exhaust valves so Ive heard the glow plugs stay on for upto 5 mins so I defo will be buying a timer for the glow pugs
 

Nick-palmer1

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I've also wondered about this as well because when the head on my nav cracked it had a crack between the glowplug and the exhaust valve on every cylinder. Anyone have some idea of the temps glow plugs get up to? glow plugs are only needed to start the engine, i think they stay on for emissions to get a better burn until the engine is up to temp, could be wrong though
 

nuckin futs

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what john said would be the go. all the old earthmoving machines i use to work on had that. turn the key to the left to heat em up, the the other way to start em
 

bods

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You only need 5 seconds of glow to fire up in a Brisbane winter, maybe more down south.

Even in Perth on cold mornings my yd25 glow light wouldn't be on more than 5 seconds... I had an old patrol that had a push button switch on it. Just wire it up to use the normal glow relay, just run the switching wire for the relay through the switch... Or the earth from the relay.....
 

rodneyrev

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When the relay trips it turns the glow plugs off as well as the glow plug light on the dash. Even in minus 2 or 3 here it starts Ok on one cycle, about 3 or 4 seconds. I also have a switch down by the steering column that gives manifold heat and presumably start overnight in the snowfields. My '04 has 300,000km on it and I think the glow plugs might nee replacing next winter.
By the way, it is good practice to cycle the glow plugs every time you start the engine.
 

Been a while

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Just wondering if anyone has done this?

Heard recently that zd30 navaras keep glow plugs on untill engine reaches operating temp, glow plugs get red hot while head is still cold and cause cracking of the head.

Anyone shed any light on this?
Waking up an old thread, I'm looking into this..

Charlie's onto it... That's what I see happening, creates a hot spot combined with there being no meat there.. They can drop valve seats from this..
Pooroll post worth a read..

 

tweak'e

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i just stumbled across this, havent had a chance to look at it yet.

(1) D22 ZD30 Glow Plug Switch Install - YouTube
meh i wouldn't bother. even the description had a few bits wrong.

d22 zd30 heads crack because the engine overheads or injector issues (and a lot of that comes from poor fuel).
the glows are based off engine temp anyway.
the best thing you can do is make sure your cooling system is working well, especially with your guys high air temps. i would have to check but i think there is an aussie thermostat for them.
 

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