Greetings,

I have been working on my old D7E and trying to get the glow plugs working. The old ones are bad and not passing continuity tests. I was not getting 24v at the glow plug wiring harness with a volt meter so I consulted the D7E wiring diagram and determined that someone had unhooked the ammeter from the battery. The original ammeter is still in the machine but it had been disconnected at some point by a prior owner. I followed the wiring diagram and got everything hooked back up as outlined in the diagram. The ammeter is working properly now and I am getting 24v on each rear post on the ammeter. Since the ammeter is connected to the starting \ heat switch, I tested the glowplug terminal on the back of this switch and I am getting 24v when the switch is moved to the heat position. Next, I tested the first glow plug lead and I'm getting 24v there as well when the switch is in the heat position. Then, I swapped out the first old glow plug with a new one, hooked up the harness lead, and then turned the start switch to heat. I immediately heard arcing and saw sparks so I let go of the switch. As seen in the picture below, it appears that the glow plug harness lead is making contact with a head nut and arcing there. The nut is very close to the first glow plug and the glow plug connector lead seems to make contact with this nut. Does this indicate a faulty glow plug harness? Or, should there be some kind of insulating jacket on the harness plug where it connects to the top of the glow plug? There doesn't seem to be much, if any, room for any type of insulator but that is the only thing that would make sense to me. It would seem like something like a spark plug boot should be here, however, my harness plugs are just bare metal as seen in the second picture. I ordered a new harness but wanted to throw this out there to see what others think. Thanks in advance for any info!

 
 

Whoever put the precups in didn't time them correctly.
Bob

bluox wrote:

Whoever put the precups in didn't time them correctly.
Bob

Thanks, I wondered if that was the case. Thankfully the other 3 don't have this issue. Is there any way to correct the timing without removing the head? Any other ideas? I was thinking of grinding a little bit off that nut and adding some kind of insulating jacket on the plug. I'm definitely open to ideas!

You generally don't have to pull the head but you need some special tools, so grind away.
Bob

bluox wrote:

You generally don't have to pull the head but you need some special tools, so grind away.
Bob

Will do, thanks Bob!

bluox wrote:

You generally don't have to pull the head but you need some special tools, so grind away.
Bob

Out of curiosity, what special tools would be needed to move the precups?

ksliger wrote:

bluox wrote:

You generally don't have to pull the head but you need some special tools, so grind away.
Bob
Out of curiosity, what special tools would be needed to move the precups?
 

 

The special splined tool to undo the chambers. You also need different thickness washers to move the preheat to a different index and depending on how stuck they are a puller to pull the capsule injectors out. Some have made a puller using an old injector line nut with a slide hammer attached. I've never had that much trouble getting them out and only have the nut with a pry bar under it.

neil wrote:

If you can, you can also tighten that head nut just a little bit of a turn to give more space, and then you can grind in the middle of the nut's flat so that you don't lose any ability to tighten/loosen the nut. I would also add a boot of some description to provide insulation, despite that not being OEM, if you end up not re-clocking the chamber

 

Thanks for the reply. I was back at it today and made progress. I removed the glow plug and then removed that head nut. I put the glow plug back in and tested it with a light probe tester. I got continuity at the glow plug so I went ahead and hooked it up to the harness. I moved the starter switch to "heat" and was pleased to see the expected 5 amp draw on the ammeter. I unplugged that first glow plug and turned the switch to heat again and there was no amp draw. So, I am happy to report that at least my first glow plug is working. The others appear to be dead. This old D7E has not started without requiring a little sniff of starting fluid (lubricated style) since I have owned it. I held the switch on heat for about 30 seconds and then tried to start it. To my shock and amazement she fired up after just about 1 or 2 seconds of cranking with NO starting fluid! It's pretty amazing that it just takes one working glow plug to make such a difference. I went ahead and ordered 3 more glow plugs and I hope to have them in hand tomorrow. I took the head bolt home with me and did a little grinding on it to shorten up one of the points. This should still give me enough meat on the nut to torque it down sufficiently, while also leaving more of a gap between the glow plug. Also, I have some heat shrink tubing for electrical wire that is the perfect size to make an insulative boot for the glow plug lead. I am going to put that on tomorrow on all 4 of my leads. I'm excited to see how she starts when all 4 glow plugs are working. I will report back on my progress.

I am happy to report that after replacing all glow plugs and verifying that they work, the old beast fires right up after about 30 seconds with the glow plugs on. She isn't an ether baby after all! I did put some heat shrink tubing on all of the leads to make them a little cleaner looking and protect them from the elements. Overall I am very pleased with how everything turned out.