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A few tips I learned during my glow plug swap extravaganza today.

1. Get yourself a 1/4" drive 13mm flex socket and make sure you have 6" and 10" 1/4" drive extensions. With this combo I was able to easily remove all valve cover bolts in a matter of minutes. Even the rear ones and the ones on the passenger side next to the HVAC. This was the only special tool that really made a huge difference.


^^^like this^^^

2. The vacuum hose trick works very well to remove the glowplugs from their holes.

3. Lacking a syringe to suck the oil out of the glow plug holes you can blow the oil out with a blowgun. Wear eye protection. Make sure there is no oil around the tops of the glow plugs before removing them.

4. DO NOT drop a glowplug down the pushrod valley. I did this and it took an hour to get the sucker out. You can't leave it down there, its on top of the pushrods and could cause major damage. Take your time. After this mess, I use the vacuum hose trick to reinstall the glows as well so I was sure they were in the right holes.

5. When diagnosing bad glowplugs, make sure your meter is set on regular OHMS. If you have an autoranging multimeter, observe what range it has set itself to. I originally misdiagnosed my glowplugs because of the autoranging reporting 1.2 kOHMs not 1.2 OHMs on a few plugs.

6. I would suggest starting on the drivers side. It is actually a bit harder to get everything to the point where you can pull the valve cover as there is a bit more to remove, but once the valve cover is off there is a lot more room. Its easier to learn where everything goes when you can see it better.

7. Make sure all your glow plug leads are continuous from the switched side of the glow plug relay before buttoning up the valve cover. Clamp one lead of your meter to the stud on the relay and check the wires. It would suck to put new glows in just to have them not work.

8. Just for peace of mind, test the glows once they are removed from the truck. I hooked a pair of jumper cables to the passenger side battery and tested them for a glow. Clamp the threaded end of the glowplug with one cable and touch the other cable to the stud where the wire connects. You will know right away if the plug is good or bad. There will be a little spark as you clip the leads to it and the oil on the tip will start smoking as the oil burns off and the tip will glow within a few seconds. Once I found 3 of 4 plugs on the drivers side did not glow, I was pretty sure I had found my cold start issue.
 

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Good post. :thumbsup:

Moving to 7.3L Engine & Drivetrain FAQ's
 

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Thanks Arnie C!! It's threads like this that make this site so awesome for me! I'm just starting to learn about my F350 and being able to read easily detailed threads like this boosts my confidence before I start a job. They also help to keep tools and other misc. items from flying across the shop...
 

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i did the test on the relay its at the 11 plus volts but confused on the ohms to test plugs. I removed valve leads found the four larger pins now my ohms meter i set and not touching anything it reads 1.000 touch the leads together i get 0.000. now checking plugs black on neg and probing plug pins on 3 the meter reads 1.000 on the other 5 it goes to 0.000 then when i take it off it rises to 1.000. bad tester or wrong setting or what? i had it set on 20m i also have choises of 2000k,200kohm,20k,2000,200 anyone know which it should be set at?
 

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"i did the test on the relay its at the 11 plus volts but confused on the ohms to test plugs. I removed valve leads found the four larger pins now my ohms meter i set and not touching anything it reads 1.000 touch the leads together i get 0.000. now checking plugs black on neg and probing plug pins on 3 the meter reads 1.000 on the other 5 it goes to 0.000 then when i take it off it rises to 1.000. bad tester or wrong setting or what? i had it set on 20m i also have choises of 2000k,200kohm,20k,2000,200 anyone know which it should be set at?"

Try setting your meter at 2000k (some read as 2m) that should allow for single digit readings. The 20 m setting should have still shown a reading though. Be sure to double check the ground you are connecting the black lead to. A bad ground will show a false reading. One last thing I discovered the hard way, check the battery in your tester. A weak battery will show a false ohm reading too.
 

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Discussion Starter #6
"i did the test on the relay its at the 11 plus volts but confused on the ohms to test plugs. I removed valve leads found the four larger pins now my ohms meter i set and not touching anything it reads 1.000 touch the leads together i get 0.000. now checking plugs black on neg and probing plug pins on 3 the meter reads 1.000 on the other 5 it goes to 0.000 then when i take it off it rises to 1.000. bad tester or wrong setting or what? i had it set on 20m i also have choises of 2000k,200kohm,20k,2000,200 anyone know which it should be set at?"

Try setting your meter at 2000k (some read as 2m) that should allow for single digit readings. The 20 m setting should have still shown a reading though. Be sure to double check the ground you are connecting the black lead to. A bad ground will show a false reading. One last thing I discovered the hard way, check the battery in your tester. A weak battery will show a false ohm reading too.
1. Set the meter to 200 ohms. Good glow plugs are around 1.4 ohms resistance. If you set it to the wrong scale, you will not get accurate readings.

2. Sounds like your meter reads 1 with an open circuit (infinite resistance) and reads 0 with a continuous circuit (what you get when you touch the leads together).

3. The glow plugs that read "1" are definitely bad and have an open circuit. Replace them.

4. Verify the ohm reading taken on the other plugs was done with the multimeter in the correct range.
 

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Thanks Arnie, for the useful post. I changed the left bank before Christmas and recently the code for #4 reappeared (well...I think that's it...looked it up several weeks ago and remember it corresponded to the 2nd one on left side...now have forgotten code but will read again and double-check before I tear into it) I recall finding back then a post giving a source for the o-rings for the little ccv doghouse that sits atop the left side valve cover and now can't find it. I'm going to need those...re-used 'em last time and have a slight leak...anyway....if anyone remembers where it is...I'd appreciate a shout out or link
 

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Thanks Much! That did the trick...I was looking for this one:

Product ID: #8-004 - CCV O-rings
 

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Great OP and I appreciate the discussion about the ohm meter settings as well. One question though:

Can I ohm test my glow plugs by disconnecting the two electrical connectors on my Glow Plug Control Module and using the following diagram, test the pins that correlate to each glow plug?

It appears that the pins on GPCM electrical connectors connect directly to a corresponding glow plug. I got a reading of .9 on 6,8,2 and 4 using this method, just wanted to make sure this is a reliable way to do it, its certainly much easier than getting to that 9 -pin connector on my excursion.

 

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It may skew the readings a bit, depending on the resistance of the wires, but if they are all reading the same value, I would guess they are all going to be in the same condition. You should certainly be able to single out a bad glow plug this way, but if they are borderline readings, I'm not sure that I would completely trust them. If your readings were squarely between low and high limits, then I'd probably trust them.

If you find one or two plugs out of range, you might probe those at the valve cover to confirm before digging in.
 

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Another very simple way to test your glow plugs is to disconnect the plugs on your valve covers, remember the 2 prongs on each end of the plug are your glow plugs, take a test light, clamp it to the positive pole on your battery, turn your key on, and touch the test light to the the prongs one at a time, if the light comes on then the glow plug is good but if it does not come on then the glow plug is bad.

And always use the Motorcraft glow plugs(I found the cheapest Motorcraft ones on ebay), I have heard some horror stories from the diesel shop down the road from here about the cheap aftermarket ones breaking off in the head.

I myself had one come apart when I changed mine, the internal shaft stayed in the head while the external piece came out, luckily I was able to just soak the plug with break cleaner for several hours and tap very lightly on it with a small hammer until it finally came out, oh yeah my brother helped me he modified a pair of vice grips into a slide hammer and we clamped that on the plug and were able to jerk it out.
 
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