Ninth Glow Plug

[Poorman]

So I went ahead and installed a ninth GP on the dash this afternoon. I hooked it direct to the GP solenoid and used 10 gauge because the run was a little longer, the others are on 12Gauge. I had bought 8 knew GP's and installed them so I used one of the five good old ones for the dash mount. First try it would not glow after 8 seconds, I put my hand on it and it was cold, I checked the lead with a multi meter and it was hot, I checked the ground to the mount and it was good, I checked resistance and it was 1.1, I took it out and checked it again, 1.1, I put it back in, tightened every thing and it still wouldn't glow. So I grabbed another one of the used plugs, it also tested at 1.1ohms put it in and red in 8 seconds glowing good at 10, hit the starter and it fired up immediately a couple small puffs of smoke and it started clearing really fast, after about 7or 8 seconds the glow was gone so I hit the button again until it was good and red and everything cleaned up completely and smoothed up and idled perfectly, 1000% better than before. I really like seeing the visual, I have always gone 8 seconds but this showed me that a few extra seconds was needed to get a good glow, yes I suppose it could be from having the extra load of another GP. I'll probably never know if the plugs in the cylinders are behaving the same as the one on the dash, especially during the after glow with all the air swirling around and exploding, but I think it should be a consistent comparison to judge the glow time by. So I really liked it, it was kinda fun to use. But the real question I'd like answered is why the first plug tested good but would not glow, I have no idea how they work, can someone explain how this could happen, I tested it many times and installed it twice also testing it installed (ohm meter). Don't understand? Thanks

 

[rreegg]

Is the 9th GP floating around on the dash or mounted somehow?

 

[Brian VT]

80034 Bosch

Weird. Carparts has them but says, "Does not fit your vehicle". They claim 80024 for my 6.9L.
I just wanted to check with you maybe you made a typo.? Or is the 80034 for the 7.3L?
Or maybe they're both usable?

 

[Poorman]

Is the 9th GP floating around on the dash or mounted somehow?

Good Question, There's an aluminum frame that houses two gauges, the exhaust temp and the turbo boost, that's mounted low on the dash, behind the plastic dash is a large steel plate (factory) that it bolts to. I had a large lug that came out of an electric panel that was sized for 00, the GP threaded side fit right into it and I just tightened down the large allen set screw on it and used the existing mount hole and a self taper and screwed it to the bottom of the face of the aluminum frame. It was super easy and pretty clean, and really ridged.

 

[Black dawg]

80034 bosch is for 6.2-6.5 application. connector is different, but well worth the effort for a manual set up.

 

[Brian VT]

80034 bosch is for 6.2-6.5 application. connector is different, but well worth the effort for a manual set up.

Gotcha. Thanks.
I have a manual set up. Do you know if the connectors are available or would I need to go to a junkyard and get them off a 6.2-6.5? (not that I know what those are yet)

 

[Black dawg]

The plug just has a male spade connector on it. Just not wide like the 6.9.

 

[franklin2]

But the real question I'd like answered is why the first plug tested good but would not glow, I have no idea how they work, can someone explain how this could happen, I tested it many times and installed it twice also testing it installed (ohm meter). Don't understand? Thanks

If you want that question answered, you are going to have to use your meter. This is the same method to test the starter system.

When the glowplug wasn't glowing, you then need to take your meter, put it on a scale that will read 12 volts dc, and then put the meter leads across the glowplug to read the voltage the glowplug is getting WHILE YOU PRESS THE BUTTON. That is the only way to do it. If you read 12v from the tip of the glowplug to the threaded part of the glowplug, and it will not glow, then the plug is bad, even though the resistance test good.

But you may find when it was not glowing, you may have only had 3 volts across it or something low like that. If that is the case, then you know you have a connection problem. Either the power or the ground. That is the reason to put the meter across the glowplug itself. Don't ground the meter somewhere else and then probe the glowplug. Use the ground the glowplug is using for the meter reading.

 

[Poorman]

Just thought I'd give an update before this thread completely dies off. I've been living with the 9th GP for a week now and I absolutely love it, I glow until the very tip starts glowing and the glow will then start running up the one inch long electrode, when it gets about 3/4 of the way up it I release and hit the starter, it starts fast, then after about 5-6 seconds the glow has traveled back down the electrode to the tip and is just red, I then hit it again and light it back up 3/4 of the way up the electrode and the engine smoothes out nice and the smoke diminishes. I taught my brother the glow pattern I'm looking for and then had him watch a GP attached to the harness under the hood, I would yell the instant the one in the cab got to 3/4 glow and he confirmed that the one on the harness glowed exactly the same, and yes we started with two cold GP's.

That is the reason to put the meter across the glowplug itself. Don't ground the meter somewhere else and then probe the glowplug

Can't say for sure but I know I put one lead on the spade and the other on the body or possibly the lug holding it, I just remember seeing 12 volts. I did take the GP that ohm,ed fine but would not glow and with channel locks pushed the spade into the positive battery terminal and then with a long screw driver grounded the body over to the ground terminal, it would not glow I tried it many times, would not glow, I tried it on all the other used plugs, all the ones that OHM'd ok glowed, the two that didn't, didn't. Then after many attempts the plug gave up and stopped ohming good. So my takeaway is that ohming a GP isn't a perfect way to test it, it can give you a false positive, the only way to be 100% sure is to pull it and see if it will glow.
If any negative issues arise later down the road I'll post them

 

[franklin2]

The more you use the manual switch and start the truck, the more you will get used to a normal start. If you lose one plug you will notice that cylinder missing when you first start the truck.

I would be interested to find out what happens as the weather gets colder. Will your ninth glow plug naturally compensate and take longer to create your glowing pattern for good starting as the cab gets colder for a morning start? Or will it just create the same pattern but the engine gets harder to start and you have to change your glowing time.

 

[Azidiguy]

Will the 6.2/6.5 one fit the 6.9?

 

[IDIBRONCO]

Will the 6.2/6.5 one fit the 6.9?

Yes they will.

 

[Azidiguy]

Yes they will.

Cool good to know i actually have both wife has an 82 c20 6.2. Be handy to have both use the same plugs.

 

[IDIBRONCO]

The biggest external difference is the smaller spade terminal on the top (6.2/6.5) as far as I know.

 

[Black dawg]

Just thought I'd give an update before this thread completely dies off. I've been living with the 9th GP for a week now and I absolutely love it, I glow until the very tip starts glowing and the glow will then start running up the one inch long electrode, when it gets about 3/4 of the way up it I release and hit the starter, it starts fast, then after about 5-6 seconds the glow has traveled back down the electrode to the tip and is just red, I then hit it again and light it back up 3/4 of the way up the electrode and the engine smoothes out nice and the smoke diminishes. I taught my brother the glow pattern I'm looking for and then had him watch a GP attached to the harness under the hood, I would yell the instant the one in the cab got to 3/4 glow and he confirmed that the one on the harness glowed exactly the same, and yes we started with two cold GP's.

Just remember that the cylinders that are firing are heating the plugs, and your plug in the cab isnt accurate to that condition.