Guide: Testing Glow Plugs

[Jenkosowls]

When glow plugs fail or start to cold starting becomes difficult as diesel need the glow plugs to start the combustion cycle. once warm its not much of a problem as heat in contained within the engine.

The tests are real simple but its always advisable to replace a whole set of plugs rather than just 1 as shortly after often the rest fail.

1) You need a voltmeter the first thing you do is measure the voltage along your battery take note as this is the figure you use to test your plugs.


2) Next you need to remove the power rail along all 4 plugs.


3) Now leave the positive prob on the positive terminal of the battery and then place the negative prob on the end of the glow plugs where the power rail attaches. Make sure you get good contact and dont use the point as this can give false readings if the contact is dirty.


4) If the Glow plug is ok you will get a reading roughly the same as the battery reading


5) If the plug is dead you wont get a reading back if its failing you may get a lower reading in my case 1 plug was dead the other was failing with a reading of 4.5v


6) To confirm the plug is dead you can use jump leads to test them first of connect the the leads to the battery terminals as normal then place the positive clamp onto the end of the glow plug


Then place the negative onto the body/shaft of the plug. A working plug will give off a small amount of smoke as it starts to work this is just crap being burnt off. Be careful this is extremely hot and remains hot a lot while longer.


If your at this stage you may as well have just put new in but its always nice to know you've got spares in the event you need one.

[RJDubya]

Thats a good guide, wish it had have been on a week earlier as i did mine on saturday. Will help a lot of people out. Mine were the same as yours 1 completely dead and 1 reading a lot lower than it should.

[Slam Wagon]

I didn't have a voltmeter so i just removed them and tested with jump leads and a spare battery. Just remember if they are working then they will get hot so its best to put them in a vice or use a set of pliers/grips to hold them.

[Face.]

Good guide.
Shame you don't have a guide to use a voltmeter lol.

I do the same as the above.

[Piggy]

another accurate way to use to your voltmeter...

set it to OHms and test how many you get between earth and the glow plug terminal...

under 2ohms is ok, around 1.1-1.3 is ideal, higher than 2ohms and they are failing

[Face.]

another accurate way to use to your voltmeter...

set it to OHms and test how many you get between earth and the glow plug terminal...

under 2ohms is ok, around 1.1-1.3 is ideal, higher than 2ohms and they are failing

In English please lol.

[kernow_joe]

In English please lol.

whack that dial round to ohms and link the bugger up!

read the output
more than 2 you're f*cked
1.3 - 2 you're safe for now

1.1-1.3 all's good