So when I purchased my '93 idi turbo 7.3 truck I was told it needed glow plugs, today I attempted to undertake the task of replacing the tired old plugs. Cylinders 1,2,4,6,and 8 all changed without a hitch... Cylinder 3 broke off flush with the top of the head, cylinder 5 was rounded off before I got too it, and cylinder 7 unthreaded but would NOT budge from the head. So I tightened #7 back down and attempted to fire the truck. Cycled the glow plugs, the light stayed on for I would say 7-10 seconds and I hit the key the second it turned off. No fire... To top it all off I found a loose plug connection on the driver's side of the engine dangling under the truck that is a constant hot, found out when I pulled it up and it touched the manifold. Please help, at this rate I'm ready to replace the wheel bearings and post it back for sale.

 

on the #7 plug use some Carb cleaner on it ... since it will unscrew the heat element is probably swollen and Carb cleaner will help break up carbon and you might be able to work it out with some Long Nose Vise Grips. this can take time so be patient with it, try not to break it off.


on #5 try a 10mm 6pt deep socket ... you might add some penetrating oil on it too.

on #3 the only way I know is to use Glow Plug extractor tools .... there are several style tools on the market none are 100%
Here is a Video to help you understand some of the techniques


IF you break pieces of the Glow plugs off you may remove the injector of that cylinder and be able to remove it from the pre-Cup other than that you are looking at cylinder head removal.

As far as the connector take a picture and post it and we can probably identify what it is and help you with that.

 

This is the unidentified constant hot plug, please ignore the leaked on oil filter...

This was another group of wires I found under the driver's side that had been cut and left dangling

Here are some things in question besides the obvious problem with my glow plugs.

 

that first pic looks like the Brake switch used for the Cruise control.... on my 93 I just jumpered it when I installed cruise control......


I cannot tell anything from the 2nd picture I have Old eyes, maybe someone else can see something.

 

It looks looks the wire in the top pic is jumped. I can't make out the second one either. Left frame rail--fsv, sending units,...Isn't there a wire going back to the rear?

 

I'll have to look at it tomorrow, hope it doesn't rain, and the top pic it is jumped.

 

like I said ... the top Pic looks like the Cruise control Brake switch and my truck did not come with cruise control... I grabbed the Servo and the steering wheel control and installed it myself and I jumpered that connector as I did not have the switch installed on the master cylinder.

the wire harness was already set up for cruise control but my truck did not have it installed.

 

Truck has factory cruise but it doesn't work. No real worries, it's a work truck, not cruising across the U.S. in it.

 

IF it has Factory cruise then it has a pressure switch on the Master Cylinder ... do you have that switch ???????

IF not then it might explain the connector being Jumped.........Just saying

while this is not a Diagnose why the Cruise control don't work Thread ... I'm trying to tell you what the connector might be... take it for what it's worth...it don't have anything to do with your Glow plug issues... I can tell you that for sure.



Now IF you want help with the Cruise control not working we can for sure help you with that too

 

Iirc when I had a rounded off glowplug I hammered a 3/8 6 point socket onto it and was able to get it out.

For the stuck ones I put a towel over it and whip the motor over. Most of the time they spit em out. If they don't then you can attack with carb cleaner, oil and vice grips.

Now I also think on some that wouldn't come out, I hooked an impact to them and let them spin for ten or so seconds too to help them break the carbon off of them.

The glow plug controller isn't going to like only 5/8 working and likely won't cycle long enough. It could also be bad but so far sounds like it's trying correctly.

Have you tried disconnecting the glowplugs and giving it just a sniff of ether to determine it's actually the glow plugs fault it won't start?

It could also be your batteries/starter/cables aren't up to par and not spinning it over fast enough. These engines need a certain cranking speed to want to start cold. Hot they generally crack pretty easily.

I would focus on getting the bad plugs out and replaced, then the rest of the system once that's done.

Like lonewolf said those wires don't affect the glow plugs.

If you can at least get 7/8 glow plugs in there and working it'll probably be fine.

If you don't feel comfortable and don't know or can't afford a reputable shop then I would just sell it and hold out for a better one.

 

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ correct
3/8 is just a bit smaller than 10mm

the proper cranking RPM is 200 RPM

maybe do manual GP control then 1,2 or 3 missing plugs won't matter so much BUT the controller will detect missing or bad plugs and will not cycle proper.

 

With a small snort of ether the old girl spins right up and runs smooth. Thank you for the advice, I feel I'm armed with the knowledge to get this fixed up. It only has 233k miles on it and am hoping to keep it for a number of years.