Hello gents,
I have recently been having some difficulty with the 6.9 cold starting. The WTS light does stay on for roughly 10-15 seconds, and I do hear the relay clicking. In 32°F weather all that I would get is white smoke which says that it is getting fuel, with the smoke being accompanied by the occasional hit.

Curious as to if just one glow plug was bad, I did the probe light test on the plugs and the light lit up on all of them. This made me question if they were all truly good, as the truck should have started with one cycle (The other 6.9s and 7.3 on the farm all start fine in the same conditions) .

Today I removed the 5 Cylinder's glow plug to see if there was build up on the tip (5 Cylinder was easiest to reach) . The plug looked like a typical used glow plug, so I hooked it up to a 12V battery just to see if it would glow. The plug didn't glow, though according to the probe test it should have. I put the plug back in the engine as I didn't have any spare plugs to throw in.

After I got the plug re-installed and hooked back up, I tried to start the truck just for the heck of it. After the first cycle I tried to start it, to no avail. Let the truck sit for 2 minutes and tried again, with it starting this time. (Roughly 40°F when trying to start)

I haven't encountered a problem like this in any of the diesels we have, so I figured I should get a couple more opinions before I ordered a new set of glow plugs in the event that it is something else causing the problem.

Also should point out that the glow plugs are Champion CH-80s

Any help is appreciated!

 

When you do the GP test with the test light you need to disconnect the wire from the GP first.
Obviously the one you hooked up to your battery is dead, sounds like more if not all are dead as well.

 

I do think that they are all dead since it would not start easily in relatively warm weather. What stumps me is that the controller still cycles normally. I always thought that when the plugs are bad the controller would cycle them fairly quickly.

 

That's only on the new style controller, 87-94, the older style 83-86 doesn't care if any of them are any good or not.

 

Completely forgot that it was the newer style that did that. Thanks for the reminder.

On another note I got all but one plug replaced today (with only one of the old plugs having a swelled tip. A pair of pliers supplied the grip I needed to pull it out) . There was one plug that wouldn't come out as it was broke right at the base of the nut, and therefore not allowing me to get a socket to stay on it. I am hoping I can figure out a way to remove it without engine surgery. Worst case I will just rely on the other 7.

 

be certain that you get the correct gp for your controller and it will work fine.

 

also be certain to only buy motorcraft plugs, no other brands. i've driven 100000 miles on one set of motorcraft plugs i installed, with the only failure being the wire to one of them. other brands of plugs tend to burn out quickly.
also, i've heard of plugs passing the test light check but still not glowing, maybe this happened to yours

 

I put in the ZD1s. Sometime in the engine's past someone must have tried to save some $$ as some were AC Delcos and others were the Champion CH-80s which tells me they got replaced as they went bad.

After sitting in the shop overnight she fired right up this morning. Glad that I found this site before I bought any glow plugs. Would have never known about how inferior the other plug brands are.

One thought that crossed my mind for getting that broken plug out was to use a Dremel tool and put a notch in the little bit of the nut that is left to try and get a screwdriver in there and turn it out. I am unsure of how to go about that since it is the farthest back plug on the passenger side that broke. If anybody else has an idea of how to get it out without pulling the head I would be more than willing to try it.

 

Make sure that your piston for that cylinder is at TDC, pull the injector, tap the end of the glowplug down into the pre-cup, put a shop-vac in the injector hole and blow through the GP hole with compressed air. It worked for me; however it took about 10-15 mins of playing with it to get it to come up out of the injector hole. Patience is key!!!

Do make sure that the cylinder is at TDC otherwise the broken gp can fall down into the cylinder!!!

The injector hole is just big enough to let the swollen gp tip come out of it.

 

The timing mark is found on a little plate that is on the front of the engine on the passenger side. The plate is mounted so it is very close to the main pulley on the lower front of the engine which is mounted on the vibration damper. On the side of the vibration damper, is a line, which when lined up with the line marked (O) on the plate, tells you that the #1 piston is at TDC(top dead center) You can see the line on the damper, and it points to the line on the plate with the (barely visible)O mark on it.You'll have to find a way to turn your engine over by hand (Crank/harmonic balancer bolt). Make sure you remove the power wire to the injection pump(so the engine won't start)and then rotate the engine until you can line up the marks.

The engine rotates in a clockwise direction as seen from the front of the truck, and for every 1/4 turn of the engine(crank) each next piston will arrive at TDC. So, When the line on the vibration damper is at the 2 oclock position, cylinders 2 and 5 will be at TDC. When the mark is at the 5 oclock position, cylinders 7 and 6 will be at TDC, 8 oclock has cylinders 3 and 8 at TDC, and back to 11oclock, 1 and 4 will be at TDC.

Cylinder numbers are assigned 1,3,5,7 on the right (passenger USA) bank from front of truck to back, and 2,4,6,8 on the driver's side (USA), front to back. Firing order is 1,2,7,3,4,5,6,8.

Edit: I just caught that it broke at the base of the nut, soak it in penetrant oil for a couple of days, and you may be able to get it out with an EZ-out... The other option is to get a left-hand drill bit and drill through the center of it, (with the engine TDC on that cyl) with a LH drill bit it may thread out on its own, otherwise you can bend an edge of it in slightly with a chisel(to break it loose) and use an EZ-out on it. Be sure to vacuum the pieces out of the cylinder and you should be OK.

I recommend installing the new GPs with anti-sieze on them..

Hope this helps,
Good luck
Bill

 

One other thought, I don't think that it is a good idea to run with just 7 glow plugs as the old style controller doesn't compensate for the missing plug. This will cause the other plugs to get over-voltage and burn out quicker.

 

Thanks for the recommendation Bill. I will see if I have an EZ-out that will fit the glow plug. Hopefully I will have it out and replaced by the end of the weekend.

I am a little confused about this part. How would the other GPs be subjected to an over-voltage state when only 12V is being fed to them?

 

The total draw from each gp drops the voltage down a certain amount. a 12V glowplug is actually a 6v gp run at 12 volts but due to the amperage draw through the harness the voltage drops down to an acceptable level for the plugs.
When one plug is not drawing any amperage, all of the other gp's will get a higher voltage and therefore heat up faster. Our old-style controller will not compensate for the voltage difference by cycling faster. This causes the gp's to overheat and burn out much quicker.

Hope this helps

Bill

 

IMO the over heating of the remaining plugs is the reason they went to a feed back type controller.

 

I think so too. It should be noted though that even the feedback controller allows for one burned out GP.