Glow Plug Conversion Questions

[broknindarkagain]

I have a box of AC60s that I'm going to put into my 1009. I'm reading about people bypassing the resistors behind the air cleaner. What is the point of bypassing them? My system seems to work fine right now, I'm swapping out the glows for a maintenance thing.

 

[AECS]

The resistoor drops the 24 volts to 12. It is a series parallel circuit so if one fails the voltage on the remaining plugs goes up and burns the rest in short order. Bypassing the resistor and tying into the 12 volt buss reduces the chances of that happening.

 

[Recovry4x4]

Answers here in the CUCV Helpful threads section.

http://www.steelsoldiers.com/showthread.php?121398-GP-Resistor-Bank-Bypass

 

[Westech]

The only issue I have seen from doing the bypass is the first battery really gets a work out.
I would install a large 1000+ CCA battery. The first battery is heating the glow plugs and doing 1/2 of the starting work.
Other then that little downfall its a good mod.

 

[dougco1]

I have a box of AC60s that I'm going to put into my 1009. I'm reading about people bypassing the resistors behind the air cleaner. What is the point of bypassing them? My system seems to work fine right now, I'm swapping out the glows for a maintenance thing.

If it isn't broke why change it. It has been doing its job for the last 25 years, might just as well leave as is.

 

[Westech]

because when one glow plug fails with the resistor in place the voltage goes up and spikes the rest of the plugs and then a snow ball effect takes place and burns the rest of them up and can damage the glow plug control card.

 

[dougco1]

because when one glow plug fails with the resistor in place the voltage goes up and spikes the rest of the plugs and then a snow ball effect takes place and burns the rest of them up and can damage the glow plug control card.

If one or more plugs fail, its most likely one of four things; The plugs are old and are due for replacement, They are of inferior quality, the original glow plug system has been altered or there is a mechanical issue when trying to start the truck (hard starting) weak batteries, fuel leaks and such. When one or two plugs fail you should replace all eight as for the original older plugs will have built up some resistance as compared with the newly installed plugs, over heating the new ones and creating the possibility of burning them out as quickly as you can replace them. The snow ball effect will still happen with the plugs weather you remove the resistor or not. (They are still all 12 volt glow plugs). If the plugs failed prematurely because of a manual glow plug switch, then you are your own warranty. These CUCVs were built rugged and designed well. If properly maintained and not altered, you should have years of dependable service.

 

[doghead]

You do not seem to understand the original design to make such a statement.

One other real consideration with the original system that we as private owners do not have is, the Government has a much larger budget than we do(aka money does not matter).

The snow ball effect will still happen with the plugs weather you remove the resistor or not.

Absolutely incorrect.

 

[Westech]

No the snow ball effect will not happen if the resistor is removed. You are not understanding how the factory system works.

With the Resistor in place with all 8 glow plugs working output of the resistor is 12V (ish)
when one plug fails the voltage goes up, second plug fails and voltage continues to rise ect ect ect
So then the good plugs are taking more and more voltage until they fail or become damaged.
If you bypass the resistor you can only supply 12V and not more. If and when a plug fails the rest do not receive more voltage.

 

[dougco1]

You do not seem to understand the original design to make such a statement.

One other real consideration with the original system that we as private owners do not have is, the Government has a much larger budget than we do(aka money does not matter).

Absolutely incorrect.

I apparently did not know the correct definition of "snow ball effect" and I stand corrected for using that term loosely. What I should have said is that the "poor mans effect" will happen when you replace one or two plugs VRS all eight. The original plugs will still have more resistance than the new ones causing more energy to be supplied to the new ones and over heating them causing the new plugs to fail. Weather it be heat build up from longer heating times or it be from more voltage causing more heat that ultimately causes the; hears that term again "snow ball effect" I learned this the hard way back in the 80s with my work trucks. Couldn't understand why I was going through glow plugs, starters and batteries. I was a poor man back then and I would only change one plug or one battery at a time. Not realizing I was just making matters worse and keep on cranking on the starter and jump starting till the starter would burn out. Good batteries good glow plugs good starter makes for quick starting, less ware & tare on the whole system. And yes I believe I do understand the original design to make such a statement. That's my opinion.