Glow Plug Brands
Senior User
Joined: Nov 2009
Posts: 169
Likes: 0
From: Missoula, MT
How does a glow plug go bad? I hooked up one today to the battery and grounded it on the radiator support and it got hot and the tip actually started to deform. Guess it wasn't what I thought it was...I mean with the name glow plug I expected to see that thing red hot but no dice.
Postmaster
Joined: Apr 2009
Posts: 4,086
Likes: 1
From: Malahat/Cowichan Valley
what brand was it? If it was motorcraft beru it wouldnt have deformed. I have yet to see one ever deform. They will burn out after about 30-60 seconds continuous but they wont deform. If you did that, i would bet you had autolite or bosch.
Senior User
Joined: Nov 2009
Posts: 169
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From: Missoula, MT
Brand was the AcDelco type and I will mention that the ones I originally replaced were Autolites which a few were swollen and also on one the tip was mangled as in deformed. What a pain to get the old ones out. I'll be getting the Beru plugs next time it's time to change them all that's for sure. I only held the plug grounded for about 15 seconds and that was enough to do it and since I wasn't getting the glow expected couldn't tell what was going on. You can bet I wasn't going to grab it to find out! lol. But I did meter the resistance to see if it was changing while heating and it did a little bit, something like 2 ohms. Curiosity killed the cat and the plug in this case.
Postmaster
Joined: Apr 2009
Posts: 4,086
Likes: 1
From: Malahat/Cowichan Valley
There is no way to burn proof a plug but they can be made to a standard that eliminates swelling and deforming. The acdelco brand is produced by autolite for some applications i believe. Either way, they are both crap and so is bosch. Berus all the way.
i ain't rite
Joined: Mar 2005
Posts: 65,447
Likes: 5,517
From: Marlboro Mental Hospital.
this shaves a little bit of the swollen tip off as you are pulling it up until it comes out.
i have used this method of removing stuck glow plugs over a dozen times, and have gotten every one out that i have used it on.
remember though, patience is the key. if you rush it, you will snap the tip off, and then you will be pulling the head.
Senior User
Joined: Oct 2004
Posts: 321
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How does a glow plug go bad? I hooked up one today to the battery and grounded it on the radiator support and it got hot and the tip actually started to deform. Guess it wasn't what I thought it was...I mean with the name glow plug I expected to see that thing red hot but no dice.
GP's go bad because the internal resistance increases to the point that they don't glow anymore. They just get 'warm' or 'hot' (sorta). To start an IDI motor on a cold morning, they need to GLOW. If the GP's are removed from the head, you can do the 'hook it up to the battery and watch 'em glow cherry red' test. If they're installed, you can also test them in place by reading resistance from the connector to the cylinder head/block. According to the Ford shop manual for the 6.9, good GP's will show 1 ohm or less. I tried reading resistance on several new ZD-9's and sure 'nuff, each one read exactly 1 ohm.
Senior User
Joined: Nov 2009
Posts: 169
Likes: 0
From: Missoula, MT
I've only got a digital Radshack meter and all the plugs read open as in no reading when read between the connector and the hex part of the plug. Could it be that all new plugs have gone bad in a couple weeks? Guess it's time for a cheap test light.
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i ain't rite
Joined: Mar 2005
Posts: 65,447
Likes: 5,517
From: Marlboro Mental Hospital.
i have seen ac delco and autolight plugs burn out after one start.
Senior User
Joined: Oct 2004
Posts: 321
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depending on what cylinder it is in and if you can get a cordless drill on the end of the plug,i spray the threads with pb blaster, then spin the glow plug slowly with the drill as i gently pull up. then i will push the plug back down a bit and respray it, and start again. i repeat the spray/spin/pull until i get the plug out.
this shaves a little bit of the swollen tip off as you are pulling it up until it comes out.
i have used this method of removing stuck glow plugs over a dozen times, and have gotten every one out that i have used it on.
this shaves a little bit of the swollen tip off as you are pulling it up until it comes out.
i have used this method of removing stuck glow plugs over a dozen times, and have gotten every one out that i have used it on.
Postmaster
Joined: Apr 2009
Posts: 4,086
Likes: 1
From: Malahat/Cowichan Valley
Yeah you would be the first in that department. I installed a complete set of bosch plugs and it started perfect once, then the second time it failed to start. Every damn plug failed. i am just glad they didnt swell.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
A couple posts back someone asked about how they fail.
A glow plug has a heating element, sort of like a light bulb.
And just like any element they will eventually fail.
Also just like any element they do degrade with every heating cycle and become less effecient.
A new plug with a good meter will ohm out at .5 ohms.
So with 12 volts applied it will draw 24 amps of electricity.
As you use them the resistance starts to increase.
By the time the plug has 1 ohm od resistance, the amps drawn are down to 12 amps.
So now the plug is making 1/2 the heat it was when it was new.
Also with the new style controller on the 87 and newer engines, the increased resistance starts to affect the glow time, since it is controlled by the resistance feedback from the glow plugs.
That 1/2 as much heat will also make it harder to start the engine as temps get colder.
A glow plug has a heating element, sort of like a light bulb.
And just like any element they will eventually fail.
Also just like any element they do degrade with every heating cycle and become less effecient.
A new plug with a good meter will ohm out at .5 ohms.
So with 12 volts applied it will draw 24 amps of electricity.
As you use them the resistance starts to increase.
By the time the plug has 1 ohm od resistance, the amps drawn are down to 12 amps.
So now the plug is making 1/2 the heat it was when it was new.
Also with the new style controller on the 87 and newer engines, the increased resistance starts to affect the glow time, since it is controlled by the resistance feedback from the glow plugs.
That 1/2 as much heat will also make it harder to start the engine as temps get colder.
Thread Starter
|
Senior User
Joined: Nov 2009
Posts: 255
Likes: 1
A couple posts back someone asked about how they fail.
A glow plug has a heating element, sort of like a light bulb.
And just like any element they will eventually fail.
Also just like any element they do degrade with every heating cycle and become less effecient.
A new plug with a good meter will ohm out at .5 ohms.
So with 12 volts applied it will draw 24 amps of electricity.
As you use them the resistance starts to increase.
By the time the plug has 1 ohm od resistance, the amps drawn are down to 12 amps.
So now the plug is making 1/2 the heat it was when it was new.
Also with the new style controller on the 87 and newer engines, the increased resistance starts to affect the glow time, since it is controlled by the resistance feedback from the glow plugs.
That 1/2 as much heat will also make it harder to start the engine as temps get colder.
A glow plug has a heating element, sort of like a light bulb.
And just like any element they will eventually fail.
Also just like any element they do degrade with every heating cycle and become less effecient.
A new plug with a good meter will ohm out at .5 ohms.
So with 12 volts applied it will draw 24 amps of electricity.
As you use them the resistance starts to increase.
By the time the plug has 1 ohm od resistance, the amps drawn are down to 12 amps.
So now the plug is making 1/2 the heat it was when it was new.
Also with the new style controller on the 87 and newer engines, the increased resistance starts to affect the glow time, since it is controlled by the resistance feedback from the glow plugs.
That 1/2 as much heat will also make it harder to start the engine as temps get colder.
BTW do I need a certain number of posts before I can get access to edit signature? I don't have edit sig option. Thanks...Scott