2H Glowplugs

Submitted: Wednesday, Mar 16, 2005 at 01:02
ThreadID: 21258 Views:10187 Replies:8 FollowUps:6
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My old 84 Tojo is hard to start so I figured the glow plugs must need replacing.

I din't have a workshop manual for the beast and I live away from major centres so everything has to be freighted in. Asked my local mechanic who rang Repco who said that there was a 6 volt and a 8.5volt glowplug at $12 and $20 each ( for such a tiny thing ! )

Without taking the plug out I tried to read the lettering on the side of the plug and it looks like a 6 but my eyes are bad and its hard to see what it really is.

The truck is a 1/84 Landrcuiser Wagon 2H 4lt diesel. Any knowledgable blokes out there who know this engine?

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Reply By: V8troopie - Wednesday, Mar 16, 2005 at 01:33

Wednesday, Mar 16, 2005 at 01:33
hi Willem,
looking in my 2H engine manual it says they used either a super glow type with a variable delay glow timer or a fixed delay glow timer. The plugs type is not mentioned but it does say not to apply more than 7V when testing the plugs or they could be damaged.

If you have a multimeter or a small test light the plugs are easy checked once you removed the busbar that connects all of them together. There may be resistors fitted on top of the plug ( my motor did not have these) or a current sensor fitted at the end of the busbar. A good glow plug has near zero resistance on the Ohm scale of the multimeter or your small test light should come on if you connect one end of it to the battery+ and the other to the glow plug tops in turn.

When I bought my troopie second hand back in '91 only one of the 6 plugs worked. No wonder she was reluctant to start on cold mornings ;-)

AnswerID: 102624

Follow Up By: Willem - Wednesday, Mar 16, 2005 at 08:07

Wednesday, Mar 16, 2005 at 08:07
Thanks Klaus You would be another one who couldn't get to sleep :o)

I will get my multi meter and test it and let you know. I saw that the top of the plugs stuck out past the busbar with a plastic cover over them.
FollowupID: 360310

Reply By: Rosco - Bris. - Wednesday, Mar 16, 2005 at 08:21

Wednesday, Mar 16, 2005 at 08:21
Hey Willie

If it's either 6 or 8.5 V, would not the multi from the bus bar to earth give you the requisite voltage reading? Saves pulling the hooa apart.

Cheers ya old bastard.
AnswerID: 102634

Follow Up By: Willem - Wednesday, Mar 16, 2005 at 08:58

Wednesday, Mar 16, 2005 at 08:58
Thanks for the advice and good wishes, Rosco. Great to see you are still around driving the Fidei Defensor :o)
FollowupID: 360313

Reply By: Member - Bradley- Wednesday, Mar 16, 2005 at 11:36

Wednesday, Mar 16, 2005 at 11:36
a squirt bottle of that south african jungle juice will get her going every time :-))
AnswerID: 102643

Reply By: Truckster (Vic) - Wednesday, Mar 16, 2005 at 12:56

Wednesday, Mar 16, 2005 at 12:56
I thought $12 was a bargain for glow plugs?
AnswerID: 102649

Reply By: Kiwi Ray - Wednesday, Mar 16, 2005 at 13:27

Wednesday, Mar 16, 2005 at 13:27
Hi Willem
When you have removed the busbar measure the resistance between the terminal and earth on the head along side the plug they should all be much the same. They do have a set resistance, some one with a manual should be able to help there. there is 2 maybe 3 different systems and they are all described in the W/S manual, one is fixed time , one temperature controled, the other is manual control.
The supply voltage on glow plugs need not be 6 or 8 volts as the power is shared by 6 glow plugs thus reducing voltage.
If you quote the chassis number Toyo should be able to tell you all the details you need , they have the info it is just a bit of a hassle getting it
Hope this is of some help
AnswerID: 102650

Follow Up By: Rosco - Bris. - Wednesday, Mar 16, 2005 at 14:28

Wednesday, Mar 16, 2005 at 14:28

I think you'll find voltage will not drop. Potential difference (voltage) remains constant, current (amperage) varies. Voltage drop is a common misnomer, which does not in actual fact occur.

FollowupID: 360337

Follow Up By: V8troopie - Wednesday, Mar 16, 2005 at 16:07

Wednesday, Mar 16, 2005 at 16:07
Agreed, Rosco, the glowplugs are all connected in parallel so all get the same voltage.
What that voltage will be will depend on the value of the resistor that's usually fitted somewhere in series with the glow plug busbar and on the total current drawn.
My 2H manual also shows individual series resistors, mounted on top of each plug though my 2H motor did not have these.
FollowupID: 360343

Reply By: muzzimbidgie - Wednesday, Mar 16, 2005 at 19:59

Wednesday, Mar 16, 2005 at 19:59
I just spoke to my mate who's an auto sparkie. He said to also check if it has a glow plug relay behind the glove box. The contacts get gunked up and this may be the cause. He advises to wait a little longer after the glow light has gone out, see if it makes any difference.
AnswerID: 102694

Reply By: Bob Y. - Qld - Wednesday, Mar 16, 2005 at 22:24

Wednesday, Mar 16, 2005 at 22:24
G'day Willem,

Trust all well with you. We had an '84 model up for about 9 years. Did replace a couple of glow plugs during that time and very vaguely remember them being 6.3 v.
I did as suggested above, took bus bar off and tested each with m/meter.

When replacing I used a very small of anti-seize on thread, but replaced the vehicle, before ever removing them again.

Am flying to William Creek early Sat morn(departing Longreach), for UHF Telemetry Field Day. Will be back in Birdsville that night, and dropped off here, on return trip. Was going to drive down, but it's a long way, when you can't afford the time to go.

Overcast here tonight, with a few spits of rain. Satmap looks good, maybe Ingrid is going to come to the party.

Seen it all, Done it all.
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AnswerID: 102725

Follow Up By: Willem - Wednesday, Mar 16, 2005 at 22:43

Wednesday, Mar 16, 2005 at 22:43
Thanks Bob and all the other advice above. Much appreciated.

I will remove the plugs as I ahve now established they are the 6.5 volt variety. Not sure of all are giving trouble so will test each one individually.

Hope you get some rain up there in the Diamantina, Bob. It is always needed,
FollowupID: 360384

Reply By: Member - Phil G (SA) - Thursday, Mar 17, 2005 at 09:39

Thursday, Mar 17, 2005 at 09:39
Hi Willem,

84 model is the "super glow" system and have about 4 seconds before the light goes out. The first 60 series had a 20 second glow.

With the superglow system, all current goes through the intake element before reaching glow plugs. This effectively reduces the voltage at the plugs to less than 7 volts. Each glow plug pulls about 10amps.

So when one glow plug fails, the voltage supplied to the other 5 plugs will increase; this causes the other plugs to fail, so they tend to all go out in sympathy!!

Just check that you have volatge at the plugs, which rules out a problem with the relay, then do as others suggest, remove the bar, and check each plug for continuity to earth. Any plugs that do not have continuity to earth are dead. Trying to measure the resistance of a glow plug is a waste of time because it is very very low.

Your choice whether you just replace the dead plugs or replace the lot. I'd be doing the latter as they are a relatively cheap item these days, and keep the old ones as spares.

AnswerID: 102761

Follow Up By: Willem - Thursday, Mar 17, 2005 at 20:40

Thursday, Mar 17, 2005 at 20:40
Thanks Phil. Will go that way when I get to it. Too much haopening here right now :-)

FollowupID: 360482

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