Pondering Glow plug issues.

[typ4]

So, with the cold snap we are having ,the dually is not liking to start. Brandon made me a fixed 10sec timer circuit for the relay a couple months ago because I had a bad controller, or so I thought.
My controller was acting like burned out gp's and if I jumped the relay it fired right up. Smooth ,no missing yada yada. Didnt test them because they are beru and bulletproof.
Turns out I was wrong, Here is what my trials and research have unearthed. And this may be known but I havent seen it recently so here we go.
That glow plug controller is a really smart sucker. I unplugged one gp on the 4x4 and the controller short cycled, unhooked 2 and even shorter.
Well the reason it does that is to cut current to the remaining plugs so they dont get fried. With the fixed timer ,1 goes out, then another then in 3 cold start attempts they are all burnt out.
So for those with a push button system, beware, you are not solving a problem and it will leave you with a no start trying to get home in a blizzard.
Pay attention to your gp controller when it starts short cycling on cold starts.
The simple test light test works great, spark test to back it up is good also.
And for those folks with ATS or factory wastegated turbo , a 3/8 deep socket on a wobbly ,long extension under the turbo from the middle of engine gets that last gp out very easy, all 1/4 drive tooling of course.
A deep wobble socket woould make it even faster, less tools to fall of.
Hope this helps someone.

 

[79jasper]

Thinking about it, that makes perfect sense.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[reklund]

That is exactly why I'm such a proponent of the factory solid state controller. Those boys at Ford/IH were thinking when they made it and it's hard to improve it.

 

[icanfixall]

That Russ for the great explanation how the solid state controller really works. I always believed the modifying to a push button system was solving one problem but creating another. you finally have the proof of this thought. Now lets see how many convert back to the easily simplest solid state controller system.

 

[tbrumm]

Yep, if the controller starts to short cycle, I know right away that at least one of the plugs has died, or has become disconnected from the harness. Before I really understood how the system worked, I always thought the controller was the culprit too. Now this applies to the OEM GP controller. I am not so sure about the aftermarket Diesel Rx controllers being as "smart" as the original. I had a Diesel Rx controller on my truck for a while and that thing just acted weird. It just never seemed to glow the plugs consistently. I chucked it and went back to the OEM controller. At least I know what that one is doing (or not doing).

 

[lotzagoodstuff]

As always very insightful Russ. I agree that the finger isn't as "smart" as the GP controller, as the shorter timing cycles does tell you that you've got a glowplug (or two) offline.

I agreed with everything in your post except the "recent cold snap". It's never been cold in Portland

 

[typ4]

As always very insightful Russ. I agree that the finger isn't as "smart" as the GP controller, as the shorter timing cycles does tell you that you've got a glowplug (or two) offline.

I agreed with everything in your post except the "recent cold snap". It's never been cold in Portland

Compared to Chicago I agree. I've worked at O'Hare in the winter, and Anchorage, I know the difference. Lol

 

[IDIoit]

I found a 1/4" drive 3/8 deep drive swivel, I usually go behind the turbo, under the DP. #7 isn't bad, but #5 sucks the big one lol

 

[junk]

That's funny. I've always used a 10mm to do my glowplugs. I went so far as to cut down a 10mm deep socket for easier access on #5 and #7 around the turbo. Never dawned on me they were english. Should have known.

Interesting on the controller though. So if you have a good controller, but the relay on it is bad is there a replacement relay?

 

[franklin2]

I disagree. That is not the way electricity works. Each plug has 12v to it any time the controller activates the relay. The only way this is going to change is less voltage drop through the wiring, and most of you have changed the wiring and got rid of the two 10 gauge feed wires.

Let's make some assumptions and see what the affect would be with one less plug. Let's assume we only have 9v at the plugs when they are all working. And let's assume we are pulling 150amps when all the plugs are working. E=IxR, we have a 3v drop in the wiring pulling 150amps, so 3v=150a x r. So r equals .02 ohms resistance in the wiring.

Let's assume one plug burns out. 150amps divided by 8 equals 18.75. So each plug draws 18.75 amps. So the current now with one plug burnt out will be 150 minus 18.75 =131.25amps. So if we pull 131.25 amps through the same .02 wiring resistance, we get 2.625 volts dropped instead of 3v dropped. 12-2.625=9.375v So with 1 plug burnt out, the voltage in the system would only rise .375v

The reason the controller short cycles? It reads less voltage across the shunt because there is one less glowplug. So it thinks the plugs are warmer than they are, so it short cycles the system. As the plugs heat, their resistance increases. So they draw less current, so there is less voltage drop across the shunt.

 

[typ4]

That's funny. I've always used a 10mm to do my glowplugs. I went so far as to cut down a 10mm deep socket for easier access on #5 and #7 around the turbo. Never dawned on me they were english. Should have known.

Interesting on the controller though. So if you have a good controller, but the relay on it is bad is there a replacement relay?

Yes, readily available.

 

[icanfixall]

I believe what Russ was commenting on was when you change to a push button glow system... You are sending power to only the working plugs and that ends up too much so it burns out the remaining plugs. I'm no electrician but I know just a little about some things. This wont be the only time I'm wrong either so let the schooling begin.

 

[typ4]

Franklin, you missed the whole point. A fixed time uncontrolled with no cycling to limit current will burn out remaining glow plugs.
That is all I was trying to get across.
Also to pay attention to the action of the controller.

 

[typ4]

I believe what Russ was commenting on was when you change to a push button glow system... You are sending power to only the working plugs and that ends up too much so it burns out the remaining plugs. I'm no electrician but I know just a little about some things. This wont be the only time I'm wrong either so let the schooling begin.

Thanks, I was trying to keep it simple. I don't care about the math, I'm just stating what happens in the actual application.

 

[BrianX128]

So I'm curious because during troubleshooting my system a while back I had wired a spare voltage gauge to the output side of my system (part with the giant squiggly piece of metal) and I just left it in the cab as I learned that when push my button in that gauge is right at 9.5 and was curious why.

So say two of my glow plugs magically go bad tomorrow morning with franklins calculations, wouldn't my gauge show 10.5? I guess I might just keep the gauge. If it ever goes above 10 volts consistently when glowing my plugs I would at least be able to go test with a test light before I burn up more.

I had it there more for diagnosing what was happening with my push button system a while back responding and turning on my wts light but not kicking the relay and figured all of that out but never removed the gauge from inside the cab. Maybe it's got the most minuscule amount of use after reading through all of this.