Glow plugs

[MrMoMo]

Ok, been reading through all I can find and am a bit concerned with what I have found... ('84Bj 60 -Canadian 12V)

I have been getting smoke at cold startup - read that this is likely caused by lack of glow plugs. -Looked up info on glow plugs and went out to test mine. I did not check for voltage on the hot bus that connects the plugs, but I did remove it, clean it and measure resistance on each of the plugs.

ALL FOUR PLUGS measured 0ohms to ground!! This makes sense as for the smoking part... but if I have 0 ohms to ground on ALL Plugs, would this not burn out something? DEAD SHORT? To verify that I was not doing something wrong, I measured voltage (system off) from the center of the glow plug to the POSITIVE terminal of the battery (for which I should get no reading with the bus bar disconnected) I measured 12V (meaning that the center of the plug is grounded)

So...
#1)Is it possible for the engine to start with NO plugs working? (it is very rough and smokes a lot)

#2)Is it likely that another part of the circuitry is severely damaged? I can hear relays clicking, and my volt meter appears to rise in two steps (8V, click, 10V..... start.....12.6V... climb to 13V)

I was expecting to find a bad plug or two, but not ALL of them!!

Have I severely missed something?

Thanks,

Bruce

 

[cody c]

how many kms on your cruiser?

When you start it, if the glow plugs arent working at all it would take quite (like at least 5 seconds on a younger motor in warm weather) a while to start running.
If they are just getting old then it would take at least a few seconds in warm weather, longer in cold.

If it is starting after not turning it over for to long id guess you just have worn out plugs, and some cruisers (3B's) just smoke regardless until theyre warmed up.

I cant remember what the resistance should be for glow plugs (i think around 0.3 Ohms or something so it might display 0) but if you get continuity from the top of the bus to the block than they shouldnt be burnt out.

Try getting someone to check for Voltage at the bus when you cycle the glow plugs. It would eliminate the timing unit and temp sensor as a source of the problem.

If you want new plugs for a 12volt 3B you can get 10.5 volt plugs from NAPA for about $15 a piece. The part # is Y147T, they are a NGK plug if i remember correctly.

Also you may want to install a WILSON switch to help start up in cold weather.
A wilson switch is just a push button that powers a solenoid that sends power to your plugs.

If you can describe the start up a little more it would be easier to diagnose as well. As well what temp is it when you first start it? And have the glow plugs been replaced lately?

 

[roscoFJ73]

Easiest way to check your plugs is to remove them and glow them outside the engine. If you do it for too long you will burn em out but a few seconds is ok.
They will get noticably warm

Its quite normal for them to start without glowing .The better the compression and the warmer the ambient temperature ,the easier it will be.
I think direct injection are easier.

As for testing the glowplugs with a multimeter, you can just test for continuity

 

[MrMoMo]

OK, I went to a diesel repair shop today and they helped me out a bit (thank god I didn't just order pugs from toyota @ $63ish cdn per piece!) I think I may have had my Ohm meter on too high a scale, as they showed me with a plug that was out of the block. So that is good. They also explained to me that quite often what happens is the injector is dirty, and does not spray fuel directly onto the glow plug, making it harder for the glow plug to ignite the fuel.

Sooo... I asked about injector cleaner and I got some from them, they said it usually makes a noticeable difference in starting, power and fuel efficency. $10 for enough to treat 4 tanks - I'll give it a shot. - so far I have it in this tank.

Temp is around 0°C these days, sometimes up to 8°C or so, sometimes a few degrees below. Next week is supposed to be pretty cold. Engine fires within 2 or 3 seconds maximum, and smoke is gone within 5 seconds, but MAN there is a lot of it.

I should probably replace the plugs anyway, but I am spending quite a bit on the truck right now, I just got it and need to do a few things to pass safety, as well as a few maintenance things (like tach sender - toyota can't find the part#!)

I'll let everyone know how the "cleaner" works.

Thanks!

 

[cody c]

Tried the cleaner,many of them. You need to get your injectors rebuilt. I say need but it isnt that your cruiser wont run without out rebuilt injectors, its just that if the injectors arent spraying then you have droplets at the nozzle tip or on the piston that will pit these surfaces and increase overall wear on your engine.
I hated to spend the money on mine, but if you keep on the maintenance you will be rewared with high mileage.

Unless you have low km's or recent rebuilt injectors than you might want to try a hard to find product called 44K, or some other super product. But if you have over 150,000 km's on the injectors you could probally use a injector rebuild.

 

[Greg_B]

OK, I went to a diesel repair shop today and they helped me out a bit (thank god I didn't just order pugs from toyota @ $63ish cdn per piece!) Thanks!

Might be the injectors as indicated...

Also...for reference...go to any place that can access Denso...

Manual 12V

1980/10 – 1981/10 BJ60
Toyota=19850-68010 12V-10.5V
Nippon Denso=06710-1330
NGK 7493 (Y-147T old number)
Bosch 0250 202 058

Manual 24V

1980/08 – 1981/10 BJ42
1978/03 – 1980/06 BJ40
Toyota=19850-68040 24V-20.3V
Nippon Denso=067100-1161
NGK 3030 (Y-178T old number)
Bosch ???

Superglow 12V

1981/10 – 1985/10 BJ60
1984/11 – 1986/08 BJ70
Toyota=19850-68050 (51) 12V-6V
Nippon Denso=067100-1680
NGK ???
Bosch ???

Superglow 24V

1986/08 --> BJ70
1985/10 --> HJ60
1981/10 – 1984/10 BJ42
Toyota=19850-68060 24V-14V
Nippon Denso=067100-1460
NGK 2188 (Y-197R old number)
Bosch 0250 202 076

 

[cody c]

I once got the part # for glow plugs from this site and saved my ass some money too. Now i just share the things ive learned to pay back the other cruiser heads for hepling me. Its kind of a pay it forward thing sometimes, but it has comeback alot too.

 

[MrMoMo]

I was somewhat surprized that this shop reccomended trying the injector cleaner, they are a very well known shop and pretty much all they do is injectors & glow plugs. I have 216K km (135K mi) on my truck so it is probably around time for a re-build. I will likely have it done this summer when the truck is not in as much use as it is right now. I beleive in regular maintenance, and anything that is likely to improve milage is an extra reason to do it.

Thanks!

Bruce

 

[cruiser_guy]

ALL FOUR PLUGS measured 0ohms to ground!! This makes sense as for the smoking part... but if I have 0 ohms to ground on ALL Plugs, would this not burn out something? DEAD SHORT? To verify that I was not doing something wrong, I measured voltage (system off) from the center of the glow plug to the POSITIVE terminal of the battery (for which I should get no reading with the bus bar disconnected) I measured 12V (meaning that the center of the plug is grounded)

Bruce, all this is perfectly NORMAL!!

The glow plugs are electrical heaters. The MAXIMUM resistance allowable is 400 ohms, anything less is fine. If you have an open circuit (infinite ohms) you have a burned out plug. It sounds like your plugs are all OK. All electrical heaters have little resistance.

You need to see if you have power to the plugs when you start the glow cycle. You'll need help because the system will shut down before you can get there after turning the key.

 

[duckling]

Unless it is using oil, and lacking in power, the engine is probably fine. If the oil has been changed regularly, and it has not been overheated, it should give you another few hundred thou before needing a rebuild. I would not recommend the NGK plugs as they are not the right voltage and will not get as hot as the Denso plugs. NGK are 10,5 volts and will not glow as hot as the Denso's which are 6 volt. The system gives them the full twelve volts for the first 3-4 seconds then steps it down a few times. I've tried both and it does make a difference in the winter. My injectors need a change as well. don't have as much punch on the hills. 3B is an awesome engine, though.

 

[cody c]

im gonna disagreee on the 12v plug producing more heat, and the 6 volt plugs will have a short lifespan. Can anyone post what is the wattage for the 10.5 volt plug, the 12 volt, and 6volt, and then i will explain why i think this.

If i remeber correctly i believe the stock system will run 12 volts to the plugs at startup and then will cycle 6 volts while running.

 

[MrMoMo]

Well, it would appear that the injector cleaner has done something... I did not plug in last night and at -5°C thismorning, 1 glow cycle and it started right up.... NO smoke. I am more than impressed.

cruiser_guy
The MAXIMUM resistance allowable is 400 ohms, anything less is fine.

I understand this, however ZERO ohms is no resistance, which equals a dead short. Take a wire from your positive to your negative terminal and see what happens with zero ohms, now do the same with a glow plug. Zero ohms is NOT good! However, I think I must have had my scale too high, and they were not really 0 ohms. I was expecting only a few ohms at the least.

I'm pretty sure everything is working ok in the glow system - if the plugs were not operating I would not see a large voltage drop when the glow system relay was on. -true? Anyway, with the smoke gone it seems to be operating fine.

It seems to be working fine now, I'll test it again in the morning.

 

[cruiser_guy]

cruiser_guy
The MAXIMUM resistance allowable is 400 ohms, anything less is fine.

I understand this, however ZERO ohms is no resistance, which equals a dead short. Take a wire from your positive to your negative terminal and see what happens with zero ohms, now do the same with a glow plug. Zero ohms is NOT good! However, I think I must have had my scale too high, and they were not really 0 ohms. I was expecting only a few ohms at the least.

When you have an electric heater next time put an ohm meter across it. You might be surprised. My meter has a buzzer when you encounter near zero resistance and that's how I check my plugs. A buzz is good, no buzz is bad.

 

[cody c]

ok a little bit of ohms law: E=IxR , Voltage is equal to Current X Resistance

Whereas Power (watts) is equal to Voltage X Current P=ExI

If It is a 20 watt 12 volt plug it will be 1.66 amps and 7.2 ohms

If it is a 40 watt 12 volt plug it will 3.33 amps and 3.6 ohms.

If you can tell me what the wattage and voltage are i will tell you the rest but i dont have a my cruiser near me so i dont know off hand. Also tthe resistance will be slightly lower when the plug is cold, and if it isnt a expensive gauge it may read small resitances (ohms) to be 0, or continuity as we call it. I hope this helps if you didnt already know.

 

[cruiser_guy]

If you have an analog meter you will need to "zero" the gauge as well.

 

[MrMoMo]

Ok ok ok folks, I really appreciate all the basic electrical theory. I understand this stuff.... Really I do. I am a Marine Electrician, I design electrical systems all day. I understand ohms law... which is WHY this became a problem in the first place.

If you can tell me what the wattage and voltage are i will tell you the rest

Ok, 12V, 0 ohms - tell me... how many amps? - THIS was my problem.

That's right "-E-" that means your calculator cant figure it out because it is an infinate number = infinate amps = dead short.

SO.. now to further your statement...

Lets just say I have 40W plugs, and I have 4 of them. So my total load is 160W @ 12V right. So you tell me you can figure out the rest. Here is one for ya!

How long can I run my 4 glow plugs, continuously (if they could without burning out), from my stock twin 27series paralelled batteries, without discharging them below the safe discharge level?

Just messing with you - but can you give me that answer? - I can.

CruiserGuy - I didn't have my meter set to "continuity" where it puts out a tone - I had it on ohms, however I think I had it on a higher scale where the value was so close to zero it just read zero. - It was really just a stupid mistake.

Really folks, I appreceate everyone trying to help, but please read a little more carefully what I am asking - go take a nice hefty 10ga wire & strap it from your glow plug bus bar to the engine block. turn the key and see which fuse/relay blows. I understand that a glow plug should be very low in resistance, but it can't be ZERO as I stated. NO LOAD CAN HAVE ZERO OHMS or it would just be a piece of wire in the circuit - it wouldn't glow, your wiring harness would.

All electrical circuits require 3 components. A source (the battery in this case) a control (the glow relay/ignition switch) and a load (the glow plugs)

If you are missing one of these, the circuit will not operate. If a load has zero ohms, it is not a load, it is a piece of wire - in which case, the piece of wire with the highest resistance becomes the load, and starts to sizzle.

Please don't take this the wrong way, I appreceate all attempts at helping, and I am sure someone will read this who didn't understand. But please understand that I DO have a working knowledge of this type of system. -It just wasn't making sense at the time

Thanks,

Bruce

 

[vanders]

Maybe the heating element has a positive temperatue coefficient i.e.
as temperature rises so to does resistance and therefore limiting the current draw.

Your starndard filiment light globe works on the same principle.

A 60 watt globe on 240v (thats what we are on down here) using ohms law it will use .25 of an amp. (I=P/V)
If you measure the resistance of the cold filiment you get get approx 68 ohms put that into ohms law and you get 3.5amps (I=V/R)

Just a thought