Glow Plug 12 Volt Conversion

[beltfedonly]

Looking opinions on this conversion. I am not new to the CUCV as this is the 4th one that I've had. This one is a M1009 that I bought 3 months ago. It was hard to start so I checked the glow plugs and all 8 were bad. I replaced them with new military CUCV glow plugs ( Wellmans ). All was good until recently, hard to start again. Checked the glow plugs and number one plug on drivers side was bad and two more on drivers side were swollen and want come out. Have the glow plug removal tool ordered along with new G13AC plugs. Will the 12 volt conversion prevent swollen plugs if another plug should fail. Thanks, Beltfedonly

 

[Skinny]

Yes, the resistor is made to work with a properly functioning setup. Plugs failing can make the situation worse. Eliminating the resistor and going straight to 12v on the GP solenoid really has no downside other then loading only one battery while they are glowing but there are worse things...

First off you should have never put those Wellmens in. Scrap them!

Both of my 6.2's had swollen plugs. Never needed the tool. I just got the engine very hot, sprayed lube on them, and let the vice grips do the rest. Long and tedious as you may have to restart for more heat but pretty straight forward surgery.



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[MarcusOReallyus]

The stock setup is fine until one GP fails. Then it puts more voltage to the remaining GPs, which shortens their life. When the next one fails, the voltage to the remaining ones jumps up again, and so on.

If you can catch the first one right away, in theory the stock system is fine. Some people have enough experience that they can tell when one fails, so they see no need to do the conversion. The rest of us, maybe we need to do the conversion.

If you switch to the AGC60s, you need to replace the connector at each GP. It's a very simple job. You need a .250 female connector. I like to use the insulated kind.


But that's still no guarantee that a GP will never fail. They do fail, but with the conversion, you won't have the cascade failure scenario.

 

[sgms18]

The stock setup is fine until one GP fails. Then it puts more voltage to the remaining GPs, which shortens their life. When the next one fails, the voltage to the remaining ones jumps up again, and so on.

If you can catch the first one right away, in theory the stock system is fine. Some people have enough experience that they can tell when one fails, so they see no need to do the conversion. The rest of us, maybe we need to do the conversion.

If you switch to the AGC60s, you need to replace the connector at each GP. It's a very simple job. You need a .250 female connector. I like to use the insulated kind.


But that's still no guarantee that a GP will never fail. They do fail, but with the conversion, you won't have the cascade failure scenario.

Thanks for that explanation. Just learned something new.

 

[Sganderson]

If you switch to the AGC60s, you need to replace the connector at each GP. It's a very simple job. You need a .250 female connector. I like to use the insulated kind.

I didn’t know this until I had already removed the glow plugs and tried to fit the new ones on.
I ended up taking the new GP’s over to the belt sander to file the tabs so they would fit in the connector.

 

[Dispatcher7]

The stock setup is fine until one GP fails. Then it puts more voltage to the remaining GPs, which shortens their life. When the next one fails, the voltage to the remaining ones jumps up again, and so on.

If you can catch the first one right away, in theory the stock system is fine. Some people have enough experience that they can tell when one fails, so they see no need to do the conversion. The rest of us, maybe we need to do the conversion.

If you switch to the AGC60s, you need to replace the connector at each GP. It's a very simple job. You need a .250 female connector. I like to use the insulated kind.


But that's still no guarantee that a GP will never fail. They do fail, but with the conversion, you won't have the cascade failure scenario.

So then to check GP's I should be able to test the voltage at each GP, if it's higher then 24v I have bad GP's? Would the bad GP have 0v at the GP electrical connection? I just purchased this truck and it starts real hard in the cold. I do believe I will find multiple bad GP's and was planning to pull them and see if they get hot. An easier test will be real nice. If I do find bad GP's where do I purchase the 24v GP's or where do I find instructions to switch to the civilian 12vv GP's?

 

[antennaclimber]

Disconnect the green wire from the GP, use an ohm meter to check the resistance of the GP to a good ground. This is measured from the metal tab that the Green wire was on to a good known ground near the GP.
A good GP should have a resistance reading around 1 ohm. A bad GP will show a higher resistance.

The recommended GP's are the AC13G and AC60G. You should be able to get them from most part stores or online. It has been reported that the Wellman brand can swell and are difficult to remove when this happens.


60G Glow Plug

 

[Dispatcher7]

Disconnect the green wire from the GP, use an ohm meter to check the resistance of the GP to a good ground. This is measured from the metal tab that the Green wire was on to a good known ground near the GP.
A good GP should have a resistance reading around 1 ohm. A bad GP will show a higher resistance.

The recommended GP's are the AC13G and AC60G. You should be able to get them from most part stores or online. It has been reported that the Wellman brand can swell and are difficult to remove when this happens.


60G Glow Plug

THANKS!!! I did find the resistance test in the Service Manual after making that post and will be doing some testing this evening.

AC13G and AC60G, these are the 24v GP's? What is the difference in the two?

 

[antennaclimber]

You need 12 volt glow plugs, both the 13G and 60G plugs are 12 volt. The 13G will plug right in to the stock CUCV wiring. The 60G tabs need to be ground down to fit the stock wiring.
Or, you can change the connectors on the truck to fit the wider 60G GP's.

I have used both types on my trucks, can not say that one is better than the other. Just to be clear, on my trucks all 8 are either 13G or 60G. I do not mix types on the same vehicle.

The vehicles originally came with 13G glow plugs.

 

[MarcusOReallyus]

So then to check GP's I should be able to test the voltage at each GP, if it's higher then 24v I have bad GP's?

No, you will never have more than 24v anywhere unless something is very wrong with your voltage regulators!

 

[SteelNinja]

Great info thanks guys