I've got an 86 CUCV. It was converted over to a 12v system by a trustworthy mechanic. Here's the problems, and I apologize if they've been covered already:

It burns through glow plugs pretty fast. I've had to replace them about once a year (with ac delco 60g) This will be the third time replacing them, at pretty much the same time EVERY YEAR. The times I've had them out, they look clean, and none of the tips are broken or even worn-looking. I tested them with the test light hooked to pos. battery terminal to plug spade and all but two of them test bad this time.

The questions:

Is it likely that the glow plug controller is to blame for the plugs failing gradually one by one, even if they are the "self-regulating" type?

With a manual control switch, is a separate relay (the ford starter one that's always mentioned) absolutely necessary? I've seen both ways described and don't fully understand the differences. I also need to know what specific type of switch I need because I'm nervous about my lack of electrical knowledge.

I kinda want to bypass the glow plug controller completely for manual control even if it is not the culprit, since I see no reason to keep it/replace it. I've been having a tough time finding a reliable write-up for doing so. All the forums I've looked at say "It's super easy" but the explanations are often convoluted.

 

Timing for the length of time the glow plugs run is specfic - too little time it won't start, to long and you will fry plugs, if you fry the plugs by over running them the end can swell making it almost impossable to remove without removing the head - as long as it's working my advice to you is keep the automatic system intact - If you really want to do the bypass a simple push button starter switch is needed - run power to one side of the switch, then run a wire from the other side to the org. relay- on the relay remove the flat plug, attach the hot from switch to one terminal on relay - other terminal run to ground - worked on my 1983 when the controller went out, at the time a $5 switch was better than a $150+ controller - do at your own risk

 

my brother had a ford that was eating glow plugs
he had to replace the controller

BTW for a Ford it was cheaper to get parts from International than Ford