This is NOT the way to test a glow plug, a BAD glow plug can give no resistance!!
The way to check it (and to make sure!!), is by using electrical wire (connected to the battery positive, red) and look for a spark when you touch the nut of the glow plug when it is screwed into place. Be carefull not to touch the other metal parts and only touch the nut of the glow plug shortly.
@Alexamstel Actually, this IS the way, I've been TRAINED as a diesel mechanic. Although you should use a digital meter, since the true reading should be about 3ohms. You are correct however, about NO resistance (I stated that wrong), that indicates a bad plug, you want SOME/LITTLE resistance. Your way of testing may work sometimes, but isn't a good way to test them, as a plug with NO resistance would SPARK! Think of it as a short - shorts will spark, just jumper across bat terminals!
i have 2 questions for u? what about a weak reading? does that work or not so good? and now an injector question: i have an injector that will not stop leaking on the return side changed the o rings and umberilas for that bank. no loss of power nor any smoke reveiling signs of a weak cyl. what is next to stop the leak?
@mchl8 lots of silicone and duct tape :P jk, are u sure its the o-rings and not the hose(s)? and that the o-rings are the right size? and that the cap isnt cracked (happens easy)? how bads the leak?
@emoskater1212 a glow plug is what all diesel motors use to start the motor. unlike a car a diesel does not have spark plugs, the diesel motor compress the fuel and air mix so much that it becomes hot and explodes. thus creating crank power in a diesel, where as a gas motor compresses not so much and has a aprk to ignight the fuel air mix, no to answer the glow plug question. when you go to start a diesel the glow plugs will turn on for 5-15 secs to pre warm the air in the motor
@100lilabner to make the first craking and explosion easier to start the motor, with out glow plugs a diesel pick up would most likely NOT START in weather below -5C and colder. below freezing.
@chevyboy98807 you can, i've seen it. You can get one that ONLY glows at the very tip, when the entire thing should glow if its good. I might make a vid if I find another one like that. The light is a good quick reference to good/bad plugs
easiest way to do it, is take a test light hook it up to the positive on your battery then take your probe and touch the glow plug... if your test light lights up the glow plug is good, if not then its bad
Morons posting on here dont know anything WOW. you test your relay by checking the constant power post and turn the key and hurry and check the other big post (power to plugs) and if they match or are fairly close its good. If their is no out put its bad.
@mattlock666 Lets see, first it doesn't matter whether you use black or red as ground, ohms is measuring flow, so it works both ways. Two, you need to learn to read an old style meter - the 'higher' the needle goes, the LOWER the ohms number (in this case, about 3ohms). If you touch the leads on the meter directly together, the needle moves all the way to the end. Get your facts straight. Or maybe you just need to use a more 'user friendly' meter.
Ive got a 1995 powerstroke and im about to replace the plugs, I am curious if i need to replace the glow plug relay aswell, because when i test it with my ohm meter it is showing resistence on both large terminals with the truck off. I know it should be like that with truck on, but not with truck off should it? Shouldnt there be no power on the glow plug side until key is turned on. Does this sound like a bad relay to you? Thx for any help you can offer,
@humilisleo If your testing for ohms, the meter uses its own power, so a reading doesn't mean it has power. It tells you how much resistance (to flow) there is through the circuit. Think of it like checking for clogged pipes. A clear pipe reads a very low ohm value.. like 1ohm. A clogged pipe reads a high value, like 150ohms. It's more complicated than just touching terminals to check a relay, and yours should be fine. Make sure you disconnected the wires to the glow plugs when you checked them
a easier test is with a test light. take the clamp lead and connect to the positive terminal on your battier and tought each glow plug were the wire connects and if your light lights up its a good plug
@tom58c On the side of your meter is a wheel, most of the time its red but it can be black to. Take the red and black leeds and put them together and you will see the metar move, when it stops moveing move the wheel on the side untill the indicator turns to O then it is diled in... Now if there is anny resistance you will know how much...sorry about the spelling I might know alot about cars but I no shit about english...
This is NOT the way to test a glow plug, a BAD glow plug can give no resistance!!
The way to check it (and to make sure!!), is by using electrical wire (connected to the battery positive, red) and look for a spark when you touch the nut of the glow plug when it is screwed into place. Be carefull not to touch the other metal parts and only touch the nut of the glow plug shortly.
no spark = bad and replace.
spark = good (enough).
Alexamstel 1 month ago
@Alexamstel Actually, this IS the way, I've been TRAINED as a diesel mechanic. Although you should use a digital meter, since the true reading should be about 3ohms. You are correct however, about NO resistance (I stated that wrong), that indicates a bad plug, you want SOME/LITTLE resistance. Your way of testing may work sometimes, but isn't a good way to test them, as a plug with NO resistance would SPARK! Think of it as a short - shorts will spark, just jumper across bat terminals!
blackhawk8427 1 month ago
i have 2 questions for u? what about a weak reading? does that work or not so good? and now an injector question: i have an injector that will not stop leaking on the return side changed the o rings and umberilas for that bank. no loss of power nor any smoke reveiling signs of a weak cyl. what is next to stop the leak?
mchl8 4 months ago
@mchl8 lots of silicone and duct tape :P jk, are u sure its the o-rings and not the hose(s)? and that the o-rings are the right size? and that the cap isnt cracked (happens easy)? how bads the leak?
blackhawk8427 4 months ago
whats a glow plug
emoskater1212 8 months ago
@emoskater1212 a glow plug is what all diesel motors use to start the motor. unlike a car a diesel does not have spark plugs, the diesel motor compress the fuel and air mix so much that it becomes hot and explodes. thus creating crank power in a diesel, where as a gas motor compresses not so much and has a aprk to ignight the fuel air mix, no to answer the glow plug question. when you go to start a diesel the glow plugs will turn on for 5-15 secs to pre warm the air in the motor
100lilabner 1 week ago
@100lilabner to make the first craking and explosion easier to start the motor, with out glow plugs a diesel pick up would most likely NOT START in weather below -5C and colder. below freezing.
100lilabner 1 week ago
you wont get one half bad. a glow pug is either good or bad, nothing in between
chevyboy98807 1 year ago
@chevyboy98807 you can, i've seen it. You can get one that ONLY glows at the very tip, when the entire thing should glow if its good. I might make a vid if I find another one like that. The light is a good quick reference to good/bad plugs
blackhawk8427 1 year ago
easiest way to do it, is take a test light hook it up to the positive on your battery then take your probe and touch the glow plug... if your test light lights up the glow plug is good, if not then its bad
chevyboy98807 1 year ago
Morons posting on here dont know anything WOW. you test your relay by checking the constant power post and turn the key and hurry and check the other big post (power to plugs) and if they match or are fairly close its good. If their is no out put its bad.
robles4242 1 year ago
do u have to have the key on? and the glow plugs un plugged?
Fravelj 1 year ago
@Fravelj key off, gp disconnected
blackhawk8427 1 year ago
this is horrible. first off black is ground, second it goes up to infinite ohms. thats a good glow plug. rednex........
mattlock666 1 year ago
@mattlock666 Lets see, first it doesn't matter whether you use black or red as ground, ohms is measuring flow, so it works both ways. Two, you need to learn to read an old style meter - the 'higher' the needle goes, the LOWER the ohms number (in this case, about 3ohms). If you touch the leads on the meter directly together, the needle moves all the way to the end. Get your facts straight. Or maybe you just need to use a more 'user friendly' meter.
blackhawk8427 1 year ago
@blackhawk8427 ohms is a mrasure of continuity, not flow.
mattlock666 1 year ago
@mattlock666 oops yea haha amps is flow :P
blackhawk8427 1 year ago
Ive got a 1995 powerstroke and im about to replace the plugs, I am curious if i need to replace the glow plug relay aswell, because when i test it with my ohm meter it is showing resistence on both large terminals with the truck off. I know it should be like that with truck on, but not with truck off should it? Shouldnt there be no power on the glow plug side until key is turned on. Does this sound like a bad relay to you? Thx for any help you can offer,
humilisleo 1 year ago
@humilisleo If your testing for ohms, the meter uses its own power, so a reading doesn't mean it has power. It tells you how much resistance (to flow) there is through the circuit. Think of it like checking for clogged pipes. A clear pipe reads a very low ohm value.. like 1ohm. A clogged pipe reads a high value, like 150ohms. It's more complicated than just touching terminals to check a relay, and yours should be fine. Make sure you disconnected the wires to the glow plugs when you checked them
blackhawk8427 1 year ago
is that an idi?
hotrodguy357 1 year ago
@hotrodguy357 sure is, International 7.3L IDI
blackhawk8427 1 year ago
a easier test is with a test light. take the clamp lead and connect to the positive terminal on your battier and tought each glow plug were the wire connects and if your light lights up its a good plug
chevyblazer8787 1 year ago
this is true... but what if its only half bad? light will still light... plus i don't have a light lol
blackhawk8427 1 year ago
lol your right about that
chevyblazer8787 1 year ago
IS THE IGNITION SWITCH ON?
mcloven83 2 years ago
no, the ohms setting uses a battery in the tester...
blackhawk8427 2 years ago
Top of the glow plug where the wire plugs onto it? or where a wrench would grab the plug?
tom58c 2 years ago
where the wire plugs into it... where the wrench goes would just bypass the glow plug completely
blackhawk8427 2 years ago
I know it may have sounded like a stupid question, just making sure. My test I did today was 1.2 ohms on each one.
tom58c 2 years ago
@tom58c On the side of your meter is a wheel, most of the time its red but it can be black to. Take the red and black leeds and put them together and you will see the metar move, when it stops moveing move the wheel on the side untill the indicator turns to O then it is diled in... Now if there is anny resistance you will know how much...sorry about the spelling I might know alot about cars but I no shit about english...
MrBlaze001 1 year ago
@MrBlaze001 Its ok man, I figured this out a long time ago. I did all my videos of getting my truck running.
tom58c 1 year ago