Okay..... really off the wall question

[Ems and Jim]

Does anyone know what sort of resistance reading (in ohms) I should expect from a glow plug ? I have 4 plugs and 3 are about 0.1ohms (allowing for test leads) and the fourth is 1ohm.

It looks to me like number 4 is kn4ckerd.... any thoughts ?

[rubblebags]

Does anyone know what sort of resistance reading (in ohms) I should expect from a glow plug ? I have 4 plugs and 3 are about 0.1ohms (allowing for test leads) and the fourth is 1ohm.

It looks to me like number 4 is kn4ckerd.... any thoughts ?

Jim just looked im my Toyota repair manual.

Standard resistance at 20deg (68deg F) Approx 0.65ohms.
That is between the glow plug terminal and ground.

Geoff.

[rubblebags]

Jim just looked im my Toyota repair manual.

Standard resistance at 20deg (68deg F) Approx 0.65ohms.
That is between the glow plug terminal and ground.

Geoff.

The glow plug resistor is Approx 0.17ohms

Geoff.

[Ems and Jim]

Jim just looked im my Toyota repair manual.

Standard resistance at 20deg (68deg F) Approx 0.65ohms.
That is between the glow plug terminal and ground.

Geoff.

Cheer Geoff, you're a star

Makes me feel better... I allowed .4 for the crap leads on the crap meter, without that i get 3 plugs at .6 and one at around 1.2........ TOOOOOO HIGH methinks !

Good, had a row with the man who fitted my engine, reckoning he'd tested them and my engine was just old & tired !... Yeah, tested them by checking they got hot TW4T !!!!!!!!!!

[gemini]

Cheer Geoff, you're a star

Makes me feel better... I allowed .4 for the crap leads on the crap meter, without that i get 3 plugs at .6 and one at around 1.2........ TOOOOOO HIGH methinks !

Good, had a row with the man who fitted my engine, reckoning he'd tested them and my engine was just old & tired !... Yeah, tested them by checking they got hot TW4T !!!!!!!!!!

take the oil filler cap off when its running at normal temp if it breathes he's right

[rubblebags]

Cheer Geoff, you're a star

Makes me feel better... I allowed .4 for the crap leads on the crap meter, without that i get 3 plugs at .6 and one at around 1.2........ TOOOOOO HIGH methinks !

Good, had a row with the man who fitted my engine, reckoning he'd tested them and my engine was just old & tired !... Yeah, tested them by checking they got hot TW4T !!!!!!!!!!

Jim it says if there is no continuity replace them.?

Geoff.

[kitesurf_phil]

Just applied Ohms law to your number four and it appears to be knackered. It won't get hot enough to warm u[a a pasty. It is needing a change.

[Ems and Jim]

Just applied Ohms law to your number four and it appears to be knackered. It won't get hot enough to warm u[a a pasty. It is needing a change.

This was my theory..... dredged the triangle out of my head and came up with the wrong number (about 10amps)

I reckoned that 1, 2 and 3 are pulling near 20 amps each number 4 is struggling with 10.... bingo ! 20+20+20+20 = 80.... what size is the glow plug fuse ? Its a wild guess, but as I have 4 spare glow plugs why not !


As for breathing.... no it doesn't but thanks for the suggestion.

[Ems and Jim]

Jim it says if there is no continuity replace them.?

Geoff.

S'okay Geoff.... my meter (jap £2.50 cheapo kept at home for fiddling - the good stuff £250+ stays at the yard with the posh tools and the alarm & insurance !) reads 0 for full continuity and "1____.0" for Over range (no continuity) the higher the resistance figure, the less the continuity.... so 0.6 is good and 1.2 is baaaad. NO continuity at all means a totally dead plug - broken element etc.

Off to the garage tomorrow to pick up a plug or two

[gemini]

This was my theory..... dredged the triangle out of my head and came up with the wrong number (about 10amps)

I reckoned that 1, 2 and 3 are pulling near 20 amps each number 4 is struggling with 10.... bingo ! 20+20+20+20 = 80.... what size is the glow plug fuse ? Its a wild guess, but as I have 4 spare glow plugs why not !


As for breathing.... no it doesn't but thanks for the suggestion.

glad to hear

[Guest]

Does anyone know what sort of resistance reading (in ohms) I should expect from a glow plug ? I have 4 plugs and 3 are about 0.1ohms (allowing for test leads) and the fourth is 1ohm.

It looks to me like number 4 is kn4ckerd.... any thoughts ?

No it's the other 3 that are knackered. Less resistance means less heat generated. If they got much better at condicting they'd be a dead short and blow the fuse.

Cheers

[Koi]

This was my theory..... dredged the triangle out of my head and came up with the wrong number (about 10amps)

I reckoned that 1, 2 and 3 are pulling near 20 amps each number 4 is struggling with 10.... bingo ! 20+20+20+20 = 80.... what size is the glow plug fuse ? Its a wild guess, but as I have 4 spare glow plugs why not !


As for breathing.... no it doesn't but thanks for the suggestion.

Glow plug fuse 80A so 20+20+20+20 is a bit near the mark for the 80A fuse.
Disconnect cable from negative side of battery. Remove the glow plug buzz bar, check there is continuity between the glow plug post and earth, if there is they work, if not replace them.
Apparently you need to disonnect the negative and buzz bar on tests as
the readings could be false due to feed across the bar & negative.

[robnw67]

Change them all

Since you have to remove all of the gubbins to change one or all of the glow plugs - why not change them all?

I got the ones from Milners, so at about a fiver each - the difference is £15. It's hardly worth having to strip the system down again in 2 months time when another plug stops working.

If you have a new set in - you know you should have a while before you need to pull it apart again.

Let's face it - you'd never change just one spark plug in a petrol engine would you? And they're way easier to change.

Rob

[gemini]

Since you have to remove all of the gubbins to change one or all of the glow plugs - why not change them all?

I got the ones from Milners, so at about a fiver each - the difference is £15. It's hardly worth having to strip the system down again in 2 months time when another plug stops working.

If you have a new set in - you know you should have a while before you need to pull it apart again.

Let's face it - you'd never change just one spark plug in a petrol engine would you? And they're way easier to change.

Rob

all right in theory, but glow plugs just go at anytime, a new one isnt really guaranteed to last as long as one thats already in and working, this thread is making them sound to complicated for people with no knowledge of, or dont own any electrical test equipment, a simple test is remove the buzz bar connecting them all together, get a piece of 12v wire hold one end on the positive battery terminal, touch the thin thread on top of the glow plug if theres a spark its working ok, if there isnt its dead and needs replacing

[Ems and Jim]

Glow plug fuse 80A so 20+20+20+20 is a bit near the mark for the 80A fuse.
Disconnect cable from negative side of battery. Remove the glow plug buzz bar, check there is continuity between the glow plug post and earth, if there is they work, if not replace them.
Apparently you need to disonnect the negative and buzz bar on tests as
the readings could be false due to feed across the bar & negative.

Awwww b*gger it.... it was far toooo late at night to go thinking !!! Lucky's right of course..... low reading..... dodgy plug !

However as I didn't take the buzz bar off I'm an $rse!

I have all of the plugs from the 'retired' engine (all reading 1.2 ohms when removed) and as its only 15 mins to do I reckon I'll have a fiddle tomorra.... too late 2night, crap week at work so the pub is calling and the babysitter will be here soon (Cheers dad!)

Time for beer !!!!!!!!!!!