Don’t know Glow!

[MKurtBenjamin]

What causes your glow plug light to shut off early? Real new at this but I’ve gleaned enough to know they need to fully heat before ignition. Now the light goes off after 6 or 7 blinks. Won’t start. Figure it’s not hot enough. Wait for the equivalent of 13 and Monster starts up. Reasons??

Btw, after a Royal Purple oil change, new air filter and both differential fluid changed Monster 86’ (M100 has gone from a rest home curmudgeon to over 21 mpg so far and top speed of 58 which I think is fairly well. Grateful for such an amazing engine!

 

[cucvrus]

If it were my truck and I wanted to diagnose the glow plug system. I would pull all 8 glow plugs and bench test them. You could have 1 or more that are not glowing and they can return a false signal to the glow plug controller to protect the system. I may not have my terminology correct but that is where I always start. Get an eye ball look at them and make sure they are glowing at the tip. CUCVRUS Repair Projects | Page 6 | SteelSoldiers I have had a few that heated up against the threads and that caused an adverse no start condition. Good Luck. Report back. I will do my best to help from afar. And I always retain the stock system no ballast resistor bypass and use AC Delco 13G glow plugs. It has worked for me for 25 years and all my customer vehicles have the same stock unmolested system in them. General Motors spent millions designing it and it lasted a long time. No use hacking it up now. Have a Great Day and Be Safe.

 

[MarcusOReallyus]

MKurt, you probably should spend some time reading the Helpful Threads sticky, located at the top of the CUCV section of the forum. There is a TON of good information there.

If you scroll down a bit you'll find a good section that covers the GP system quite well. I'm sure you will find it helpful.

Other than that, listen to Rick's (CUCVRUS) advice. There are few who know these things as well as he does.

 

[Keith_J]

I found yet another use for my Harbor Freight battery load tester..yes, checking glow plugs. You need an extension for the red lead which is connected to the positive terminal on the front battery. The black clamp goes on the glow plug. Engaging the switch puts 12 volts or so through the glow plug and shows voltage drop on the load tester gauge. This voltage will drop as the glow plug heats. Beats having to bench test.
The voltage output is qualitative, the numbers mean nothing but each glow plug should behave identical. A burned out glow plug will not show any voltage.
Never energize longer than 5 seconds.

 

[cucvrus]

Beats having to bench test.
Unless as I mentioned the tip is not heating up and the shaft is heating up. I seen it more then once. I don't just try to work harder I try to work smarter but still looking eyeball to object is the best way. Ever wonder how they can take a picture of Mars from earth and you can make out the sand blowing in the breeze and other small objects. But they can't get a legible picture of someone using an ATM machine or robbing a convenience store? To me looking at something directly is the real way to identify something. Without hands, visual experience you have an assumption. And you know what assume means right? Have a Great Day. I will still R & R glow plugs. It takes just as much time and requires no equipment. just a short wire and the vehicle battery.