Glow plugs

[joel HJ60]

What is the correct method for testing glow plugs? Whether they be in or out of the engine. In particular my plugs in my 2H (HJ60).
Thanks Joel

[joel HJ60]

Anyone>? Maybe no one looks here?

[gotoy]

Glow Plug

Inspect glow plug. Using an ohmmeter, check that there is continuity between the plug terminal and ground. If there's no continuity, replace glow plug.

Glow Plug Current Sensor

Inspect glow plug current sensor. Using an ohmmeter check theres continuity betwee the sensor terminals. No continuity, replace.

Glow Plug Resister.

Check contiuity between resster teminals. No continuity, replace.

*Be careful not to damage the glow plug pipes as it could cause an open circuit or shorten the life.
*Avoid getting oil and petrol on the glow plugs when cleaning.
*During inspection, use cloth and be sure to wipe any oil off the glow plug terminals and bakelite washer.
*Be careful not to apply more than 7volts to the glow plug as it could casue an open circuit.

[joel HJ60]

Excellent, Thanks mate. So pretty much no resistance and there shot.

[-Scott-]

You want very low resistance, which may look like "no resistance" on some multimeters. High resistance or no continuity is bad.

If you don't understand the difference between resistance and continuity either spend some time with our good friends at Google, or ask here and we'll try to explain.

Good luck,

Scott

[joel HJ60]

Hmm I thought they were the same thing, obviously I'm wrong. Care to explain the difference please? Thanks Joel

[joel HJ60]

Testing Diesel Glow Plugs - Top

Testing Diesel Glow Plugs

A simple method for testing Diesel glow plugs is a continuity test. This can be accomplished by using a test light with the lead connected to a source of 12 volts. with the test light connected in this manner, wherever the probe is grounded the light will light.

To test the glow plugs, first disconnect the leads from all glow plugs, then touch the probe to the connector on each glow plug. If the bulb in the test light burns, the glow plug is good. if the bulb does not burn, the glow plug needs to be replaced. An ohm meter may also be used to test the glow plugs, resistance should be between 1.45 and 1.75 ohms.

An alternate method is to remove the injection nozzles, and have an assistant push, and hold the glow plug control button in. Observe the glow plugs thru the nozzle bore in the cylinder head. The glow plugs should become red hot within approximately 20 seconds. Replace any glow plugs that do not get red hot

I hear people say chuck them on the battery, can you explain that aswell please.

[-Scott-]

Hmm I thought they were the same thing, obviously I'm wrong. Care to explain the difference please? Thanks Joel

Resistance is literally a measure of the resistance to flow of electricity, and is a quantitative property - it has a number and units, which is independent of voltage or current (it's actually determines the relationship between voltage and current.)

"Continuity" is a descriptive term, referring to whether or not a circuit conducts. "Continuity" is only a yes/no thing; a circuit has continuity if it conducts, but doesn't if it doesn't. "Continuity" has no "official" numbers associated with it; you can test it, but not really quantify it. To quantify it, you need to measure the resistance.

Using "continuity" when talking about glow plugs is dangerous, because glow plugs can conduct but still be stuffed if their resistance is too high. If they don't conduct, they're definitely stuffed.

To confuse the issue further, there is also conductivity, another quantitative property which is literally the inverse of resistance (conductivity = 1/resistance.) A circuit with low resistance has high conductivity, and vice versa. It's not commonly used.

Confused?

Scott

[Bluey]

Hmm I thought they were the same thing, obviously I'm wrong. Care to explain the difference please? Thanks Joel

Resistance is literally a measure of the resistance to flow of electricity, and is a quantitative property - it has a number and units, which is independent of voltage or current (it's actually determines the relationship between voltage and current.)

What he said. measured in Ohms

"Continuity" is a descriptive term, referring to whether or not a circuit conducts. "Continuity" is only a yes/no thing; a circuit has continuity if it conducts, but doesn't if it doesn't. "Continuity" has no "official" numbers associated with it; you can test it, but not really quantify it. To quantify it, you need to measure the resistance.

Used for fault finding or a check that wiring is correct per application/design after installation

Using "continuity" when talking about glow plugs is dangerous, because glow plugs can conduct but still be stuffed if their resistance is too high. If they don't conduct, they're definitely stuffed.

Good call. when checking things like glowplugs, use resistance setting on multimeter. when checking wiring, use continuity or buzzer setting. (small % of time like 1-2% want to know resistance of wire)

To confuse the issue further, there is also conductivity, another quantitative property which is literally the inverse of resistance (conductivity = 1/resistance.) A circuit with low resistance has high conductivity, and vice versa. It's not commonly used.

Used normally in circuit analysis. but not much. measured in Siemens

Confused?

Then theres impedance, reactance, admittance, susceptance ....

Scott

[-Scott-]

I didn't want to get into AC circuits - all those real and imaginary components drive me crazy.

But I had to go look up some of those terms, (it's always good to learn) and discovered I was wrong.

Conductivity is a material property, a measure of it's ability to conduct. I should have been talking about conductance. Apparently some have been known to use the unit "mho" for conductance - ohm spelled backwards.

Cheers,

Scott

[Bluey]

doing AC theory at tafe, at work plus correspondance short courses from queensland uni of tech. work in power industry, pretty kewl.

more stuff i do like this can move further up the food chain, including pay levels

your right about conductivity vs conductance, didn't notice this one


yeah, Mho's gone out of favour for Siemens, think it is IEEC standard unit or something? we have protectiopn relays that measure impedance of a transmission line, when there is a fault (short circuit) to ground or to another phase, the line impedance changes and relays picks this up and trips circuit breaker(s). these relays have heaps of settings to choose/setup, some of which are called Mho (setting) graphs. so basically the relay is actually measuring conductance, inverse impedance, because closer and bigger faults will have a higher conductance than further away and smaller faults, and tripping times need to be priotised. (big conductance is bad vs real small impedance is bad. easier to measure and respond to i guess).

so there you go, conductance is actually used in the real world and not just in tafe/uni lecture rooms


Cheers
Lance

[joel HJ60]

Thanks guys I understand perfectly. I asked my phyiscs teacher and he explained it simiarly to NJ SWB ( maybe a career move there one day>? ). I get it now.

[-Scott-]

Thanks guys I understand perfectly. I asked my phyiscs teacher and he explained it simiarly to NJ SWB ( maybe a career move there one day>? ).

What? Your physics teacher wants to be a Paj driver?

Scott

[joel HJ60]

Might chuck this in the sticky at the top of the page!

[joel HJ60]

May as well ask here instead od starting another topis. I'm not sure if this is relevant or not tho. What is the best way to clean glow plugs? I've pulled mine out and seen they have a fair bit of black carbon built up. Should this be cleaned or is it normal and I shouldn't worry about it? Thanks Joel.

[Bluey]

checked my manual and all it says is to use a cloth to clean. duh! does say to make sure no oil on glow plug when reinstalling, but doesn't mention soot tho