When I got this truck a week ago, (93 F250 7.3 Turbo, 188k miles) the glow plug relay clicked a couple times a second when "Wait to Start" was on. It had, what I believe, were stock GP's, so I replaced them with Motorcraft.

Oddly, now the truck does not click when "Wait to Start" is on, but it starts clicking after the light turns off...The GP relay also smokes a little (lol). The glow plugs are working as it still starts when it's 15 degrees. I noticed yesterday that is was clicking after the engine was running for about 5 seconds and it was causing the head/dash lights to dim, along with amp meter moving.

Should I just go ahead and assume it needs the GP relay? If so, what brand should I look for? DieselRX or something was all I could find readily available.

 

On my '91, the glow plug relay is on steady for as long as ten seconds, at which time the wait to start light goes out. After starting, the glow plug relay cycles (clicks) for another 15 seconds or so, to clean up the exhaust.

So your controller seems to be operating operating correctly, but the relay definitely shouldn't be smoking. It does carry a lot of current.

The clicking of the relay before you replaced the glow plugs indicates you had a bad plug (or more) that caused the controller to short cycle.

 

Cool, thanks. I'm just going to run it until it doesn't work.

 

correct, the glow plug system is working properly now.
the "clicking" after the light goes out is the controller turning the glows on/off to help the engine warm up by keeping the plugs hot for a bit.

 

And it should have a noticeable impact on my charging system? Like my lights dimming and my gauge moving?

 

all 8 glow plugs lighting up draws close to 200 amps, so yes, it definitely will.