Humvee glow plugs

[Doug D.]

So thinking about replacing glow plugs myself. Found a really cool extractor tool from Blackdog Customs. They have a really good video also. Just wondering though---should i loosen glow plugs a little before i put the extractor on it? Are glow plugs usually hard to remove? Any help would be great.

 

[MarkM]

It's a toss up if all will come out without issue. I would pull them on a hot motor. It may help with the removal.

First three front of truck to rear on drivers side I pull from underneath. First three from pass side removal from up top. Pull the air filter assembly to make room. Last plugs on both sides I pull from inside the truck.

Liberally use penetrating oil to aid in the removal. If you must use the extraction tool spray penetrating trying to get it inside the hole. Hopefully they will come right out. Good luck.

Mark

 

[Mainsail]

Thanks to some garbage plugs, I've done mine twice now and I've only had the truck since last fall.

I did all my left side ones from underneath, hunk of foam on the creeper to give me more reach.

The right side was much more difficult, and the three aft ones were through the doghouse hole. A big zip-tie to pull all the lines and hose to one side helps. I did not remove the filter assembly, but did pull the pipe running from it to the intake. I also pulled the heater hoses off.

None of the plugs worked when the truck came from Yermo, and none of them were swollen enough to make a difference during removal. They all unscrewed easily and came right out. The "new" ones got a light coat of anti-seize during install, and the torque spec I used was "snug enough".

Truck started fine for a month or so, then got progressively harder and harder until it wouldn't start at all (white smoke from the tailpipe). The new plugs came from a reputable supplier we all know, but despite being advertised as the correct plugs and arriving in fresh boxes labeled AC Delco, were actually cheap garbage - origin unknown. So on two round two of glow plugs....

Round two was much more difficult as the "faux" plugs were swollen. Most came out with little difficulty but several needed the extractor, which I didn't (and for some-odd reason still don't) have. I was able to get all but one out using a body-panel tool that by pure coincidence fit just behind the wrenching surface of the plug and allowed me to put some pull on the plug while performing the twist-&-shout. One was very stubborn but finally came out.

So the choices before you are; learn from my mistake, or learn from your own. Make sure you're buying the mil-spec plug with the correct part number. They don't cost much more than the fakes so spend the money.

Epilog to this sad tale is it's 35° this morning and the truck fires right up with no difficulty.

 

[MarkM]

If the plugs burn out over time I believe you have a much better chance pulling them without issue then if the box fails and cooks them. You would be insane to use anything but the mil spec plugs.

Mark

 

[Retiredwarhorses]

You do not need a GP tool if the plug isn’t swollen, just unscrew and replace, tool only needed if stuck..,

 

[Doug D.]

Thanks for all the info. Have you guys heard of these glow plugs breaking before you get them out? Read a lot online and wondering if this is common?

 

[Retiredwarhorses]

Thanks for all the info. Have you guys heard of these glow plugs breaking before you get them out? Read a lot online and wondering if this is common?

ive removed hundreds, only ever had a couple separate and that was due to not being patient and using penetrating oil on really stubborn units or not using my puller, it’s not a race, take your time.

 

[Mogman]

To answer one of your questions, you want to try to pull them before using the extractor so you want to unscrew them first, as RWH and others said lots of penetrating oil and patience.
Have your glow plugs tested bad?

 

[juanprado]

Thanks to some garbage plugs, I've done mine twice now and I've only had the truck since last fall.

I did all my left side ones from underneath, hunk of foam on the creeper to give me more reach.

The right side was much more difficult, and the three aft ones were through the doghouse hole. A big zip-tie to pull all the lines and hose to one side helps. I did not remove the filter assembly, but did pull the pipe running from it to the intake. I also pulled the heater hoses off.

None of the plugs worked when the truck came from Yermo, and none of them were swollen enough to make a difference during removal. They all unscrewed easily and came right out. The "new" ones got a light coat of anti-seize during install, and the torque spec I used was "snug enough".

Truck started fine for a month or so, then got progressively harder and harder until it wouldn't start at all (white smoke from the tailpipe). The new plugs came from a reputable supplier we all know, but despite being advertised as the correct plugs and arriving in fresh boxes labeled AC Delco, were actually cheap garbage - origin unknown. So on two round two of glow plugs....

Round two was much more difficult as the "faux" plugs were swollen. Most came out with little difficulty but several needed the extractor, which I didn't (and for some-odd reason still don't) have. I was able to get all but one out using a body-panel tool that by pure coincidence fit just behind the wrenching surface of the plug and allowed me to put some pull on the plug while performing the twist-&-shout. One was very stubborn but finally came out.

So the choices before you are; learn from my mistake, or learn from your own. Make sure you're buying the mil-spec plug with the correct part number. They don't cost much more than the fakes so spend the money.

Epilog to this sad tale is it's 35° this morning and the truck fires right up with no difficulty.

What supplier had the fake delco's?

 

[Doug D.]

i have not tested them yet. Have not purchased any new ones either. Just trying to get ahead. What should they test at? 2 ohms?

 

[Doug D.]

what penetrating oil do you guys recommend?

 

[MarkM]

My go to for just about anything.

 

[Mogman]

i have not tested them yet. Have not purchased any new ones either. Just trying to get ahead. What should they test at? 2 ohms?

Yes they should be low ohms, if they test good there is no reason to mess with them.

 

[mgFray]

Lots of threads on glow plugs. But the easiest way to tell if what you have is counterfit or not is the size of the hex. Is it 3/8" or 10mm? If it's 3/8" it's probably real (I've read about both 12 and 24V plugs, 12V usually have spade connectors, while 24V are bullet style).. 10mm are always counterfit junk. Stay away.

I've ordered glow plugs from MacMotors and Kascar/Real4wd. NONE came in an AC Delco box (nor would I expect expect them to). I've only installed the MacMotors ones, but they are working well, 3/8" and after a year of use didn't show any signs of damage or swelling. Kascar/Real4wd look identical and I have them as a backup set. I paid about $7 a glow plug, vs $5 (or so) four the counterfit ones I've seen on Ebay. I don't see any reason why you would spend the money on the counterfits to save $2 a glow plug. Remember, if the hex is in mm, it's counterfit. (To be clear, I'm not against Chinese made parts, I'm against people selling them as authentic and then finding broken crap from the previous owner of my vehicle because they didn't know any better!)

 

[badger_610889]

i have not tested them yet. Have not purchased any new ones either. Just trying to get ahead. What should they test at? 2 ohms?

Yes - just installing new ones and I checked: they are all 1.9 or 2 ohms.

 

[badger_610889]

If it's 3/8" it's probably real (I've read about both 12 and 24V plugs, 12V usually have spade connectors, while 24V are bullet style).. 10mm are always counterfit junk. Stay away.

When I received the A2, the previous owner left some parts including a ziplock with new glow plugs as spares. I just checked now that I read this and you might be right: these measure a perfect 10mm which is about .02 larger than 3/8" and their resistance is 1.5 ohms vs 2 ohms. So they may work better because they will draw more current therefore heat-up hotter, but they may also burn quicker.

I thought it would be a 30 minute job but I'm struggling with the extraction on the M1123. Looks like I'll pause and get the right tools starting with an extractor. One plug has lost its end in the cylinder so I'll need to get it with a magnet...

 

[Mainsail]

I see 10mm and I want to tell you to throw them in the trash - not worth the future grief.

 

[mgFray]

The 10mm plug will burn itself out within a year, while the real thing will last a few years (at least). Throw away the 10mm, and buy the real thing. You really want to avoid that pain! (Plus the easy extractors only support 3/8" hex.. so when the 10mm does swell and get stuck it's even harder to remove!)

 

[badger_610889]

Yep, that was my point. 10mm have lower resistance = running more amps = burning faster.
I only purchase US made with SAE bolting for an American trucks, otherwise it feels odd, an whispering ‘cheap junk’…