How to test glowplugs?
Answers:
Glow plugs can and will easily last for more than 2 years u idiot. You CAN take them out and wire them up to a battery, thats exactly what happens when you first turn the ignition on, this will not damage them, touching a test light on them will only show if power is going to them not if they are actually working, and you have told them wrong anyway, you would put the test light lead on the negative not the posotive, please go and answer something you know about. The easiest way is to use an amp clamp, put it round the main feed wire going to the glow plugs and watch the reading as someone turns the ignition on, if they are good they will draw 10 or more amps each, so for a 4 cylinder you should get 40 amps or more. If you dont have an amp clamp taking them out and putting a drop of oil on them is a good way too, it just takes longer. Message to Connor - maybe u shud get some more training mate, yes the test light will light up, this shows there is continuity, one single strand of wire will light a little bulb mate but it doesnt give u any idea if the glow plug has the ability to draw enough amps for it to warm the cylinder does it! I doubt u have ever used an amp clamp or would even understand anything about amperage if u r that quick to slag off my answer, you pillock, i feel sorry for the people coming to your garage for an expert diagnosis by someone like yourself, you are obviously a fitter not a technician, people like you give the motor trade a bad name because you dont understand what you are working on.
If they`re more than 2 years old they definetly need replacing .
you can hook them up to your battery , Positive to the terminal on top, negative to the body where the threads are. Just be careful, They get really hot. If one is bad it wont produce heat
You can test them by connecting dierectly to your battery but be careful because they are VERY hot.
Otherwise, you can test the resistance between the terminal and the engine block using a multi meter.
They should be within a small tolerance of each other.
Glow plugs are relatively cheap so its often worth changing them as a matter of course.
Take them out, get a set of jumper cables and connect the positive to the top and put a drop of oil on the end of the glow plug and connect the negative to the body of the glow plug, you will soon see the oil smoke, which tells you it is working, do that with the rest of the plugs!
Do not hook them directly to the battery. Hook the clamp of a test light on the pos. term of your battery. Unplug the wire from the glowplug but do not removethe GP from the engine, touch the term with the test light. If it lights up the GP is good if it doesn't its bad. Hooking directly to the battery can damage the GP.
connect to battery direct and check
the best way to checkglow plugs is to geta car battery and a jump lead put one end of the jump lead to the battery terminal,the other end to the thread bit of the glow plug,then touch the body of the glow plug to the other end of the battery for approx 10 seconds watch the end of the glow plug it should glow if it doesnt then its capput
leave them in the head and test them with a test lamp - tom is the one who knows nothing about what he is talking about! what good is earth to earth on a test light? you connect the wire on the test lamp to the positive terminal of the battery and the tip to the glow plug - disconnect all wiring to the glow plugs - if the glow plug lights its OK if not its dead - also check if they are all the same brightness - this will signal one on the way out - this works as i am a mechanic and have done it this way - you can do it with a piece of wire too - a little crude but also works - from the positive to the plug - just touch it off the plug - the greater the spark the better the plug - no spark dead plug
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