glow plug problems - truck down

[RustyRecycledT]

Brother in law is having probs with his '93 F-350 (7.3) again. His glow plug controller just clicks. Here's where it gets wierd. He's getting a steady 11v to the glow plugs while the gpr is cycling on and off. even with that, his truck won't start in the morning.
he stuck another controller on but it didn't change anything. Glow plug light doesn't even come on, controller clicking on and off,11 volts at the glow plug.
he put an ohm meter on each gp and his meter isn't registering anything between the gp and ground.

Anybody got any insights?

thanks in advance.....

 

[BlueBreadTruck]

what I did to check mine:

test light, one lead on positive of battery, one lead onto glow terminal after you unplug the wire. Light=good, no light=bad

 

[88F350idi]

mine did the same when the plugs were shot, but be sure to test them before just replacing. i used a test light to test mine as well

 

[Goofyexponent]

If it is just clicking, the plugs are toast! What brand of plugs were threaded in there?

 

[argve]

Sounds like the glow plugs are bad - probably not all of them so test them first and replace the bad ones. Some say just replace them all but I fly by the rule of only replace what's bad - don't fix what's not broken kind of thing... Typically the controllers don't go bad.

 

[Agnem]

If your measuring 11 volts, you've already confirmed the plugs are toast. A good set of plugs, will pull the voltage down to about 6 volts when cold.

 

[antivtec]

Sounds like the glow plugs are bad - probably not all of them so test them first and replace the bad ones. Some say just replace them all but I fly by the rule of only replace what's bad - don't fix what's not broken kind of thing... Typically the controllers don't go bad.

Depends on what plugs are in there. when i replaced my glowplugs i had 3 bosch, 1 champion and 4 berus. there were 4 that were good. 3 bosch and 1 zd9. i opted to replace them all, albeit i do have a bag of about 60 brand new zd9s that i got for free so it didnt cost me anything but i didnt want to put 4 new plugs in there and have the bosch plugs go bad and swell up on me a week later

 

[argve]

the only ones that I ever had a problem with were the champion and autolite plugs. I ran wellman's for a long long time.

 

[Diesel JD]

You're describing rapid cycling. The solid state system fails in safe mode, so a dead glow plug is treated as though it where red hot. If you ahve two or more dead or disconnected glows, they may not cycle at all, that's what your brother's truck is doing. This situation=no start. I agree with Travis, just replace the bad ones. I'd want all the glows to be the same brand. ZD-9s from motorcraft work best with this system although I think the risk of having a catastrophic failure with this system(one which requires you to tear into the engine) is very small compared to the old latching relay system which did not fail in safe mode most often it stuck on. Usually motorcraft/beru plugs and some other good plugs would just burn out and could be replaced in the usual way with some patience. Autolites and Champions would often swell up and get stuck. People will tell you here beru/motorcraft only, and that is the best answer as the system was designed around them but I think the SS system allows for more experimentation before something really bad happens. That said, I have run beru ZD-9s since converting my 86 to solid state in Oct 2004 and in that time only replaced 2 gps, I am thoroughly impressed for 6V plugs in a 12V system and I do a lot of starts since this truck is my DD. A test light usually will tell you if it's good or not, most often they fail "open" where the resistance approaches infinity and a test ight will not come on, and an ohm meter will usually show nothing or just flash or some such. I think your brother was picking up on some opens.

 

[Raiden7800]

My opnion has always been that if one goes bad, the others are not long for this world. It's similar to headlights I suppose. My Volvo and my Ford both had a headlight go out. I replaced both on the Volvo, and only 1 on the truck, just to see how much life it has left in it.

I guess my point is, how many times do you want to climb under the hood? Do them all at once and you are good to go for awhile. Replace a few only, and you may be back under there in a week doing the same thing.

If you choose only to replace a few of them, mark the ones that have been replaced...

~Rob~