Glow Plugs

[dakotajeep]

So I dug under the hood and found that two of my glow plugs are bad (no voltage) and one is weak (only showing 20 volts). I assume this is enough to make the system inoperative?

Should I replace them all or is it fine to just replace the bad ones (as well as all non-Beru/Motorcraft plugs)?

Fortunately on my last IDI I never had to touch the glow plug system so I am pretty ignorant on the system. I have spent a bit of time this morning reseaching it though.

Going to try and find some GP today.

Also, where is the GP controller sensor located on a 6.9? The cylindrical looking piece....I got another one since the previous owner said it was bad...not sure about this guy though. This thing was super neglected.

Is there anyway to test the rest of the components?

Thanks
Thad

 

[icanfixall]

Motorcraft ZD1A glowplugs with the spade ends fit the 6.9 engines.... Now a Motorcraft ZD9 fits the 7.3 with the solid state controller and they are the bullet ends. The cylindrical controller you have is at best suspect. They fail and when they do its onn till the plugs burn out. You will be time and money ahead to convert to the solid state controller and the ZD9 plugs. This advise is from many others issues with the 6.9 controllers. I'm sure we will see posts of members that have never had an issue with the 6.9 controller too. The 7.3 controllers very seldom fail. What is the usual failure point in most any glow system is the harness connection for the engine wireing harness. The wires are just soo small to carry enough amps and any dirt or corrosion in the plug connecter will increase the amps and make too much heat. The connecter will melt sometimes causing an electrical fire under the hood. I saw this happen first hand one morning when I started my rig. Just as the engine lit off there was a big puff of smoke coming out from the hood and fender gap on the passenger side of the truck. I shut down and checked it thinking my new starter failed. Everything appeared normal. I could restart easily. Then I saw the mostly melted wire harness plug. It was still hot. I cut out the melted ends and replaced the wire from the fender solenoid to the controller with multi braid speaker wire. I think it was 4 or 6 gauge. Direct power to the controller now.... Now more going thru a tiny connecter plug...

 

[Shadetreemechanic]

I would replace all the glowplugs. My experience has been that if you only replace the bad ones the ones left burn out quickly. I have a suspicion that it has to do with the difference in resistance on a new versus a used glowplug. The gp relay is sensing resistance across the whole gp circut and is likely cooking the older plugs.
All new plugs should have the same resistance values and glow equally.

 

[dakotajeep]

icanfixall,

So its seems that someone has upgraded the system to the solid state type. I really think the guy that had this before me had someone he knew that was a IDI guy but gave bad infomation or someone else messed with this rig...

I am going to change out all the GP's with the ZD9's I just picked up.

Thanks
Thad

 

[dakotajeep]

Been finished for awhile now....

Replaced all 8 GP's and the glow plug system works like it should. Started right up!

I just need to put some better tires (these ones are barely enough to allow it to roll) and it will be set for driving beyond a one mile radius of my house.

Thanks to all who gave their .02 of knowledge!!!

Thad

Side note: What do you guys think about turbo'ing a rig with 337,00 miles on it. Crazy?

 

[93f250idi]

crazy? not at all. just get a wastagated system and have it wastgated to no more than 10-12 psi.

 

[icanfixall]

Turbo wont kill the engine with that many miles on it. And if it did you have an excuse to take a look inside one of these engines.. they are really built tuff. They have more soul than daddys shoes...

 

[dakotajeep]

Yeah, I guess my thoughts on this rig are more for economy. So far I have less than $700 invested in this rig between purchase price and a few parts.

Just got to thinking about it...

Thad

 

[93f250idi]

Yeah, I guess my thoughts on this rig are more for economy. So far I have less than $700 invested in this rig between purchase price and a few parts.

Just got to thinking about it...

Thad

do it! ive got a few hundred set back for a d60 or a turbo. just cant make up my mind lol. guess ill just keep throwing what i can in there untill i get enough for both