New Glow Plugs Installed; Starts Worse Than Ever

[cucvrus]

Don't get excited. It is not the end. Which 2 are stuck?

 

[Warthog]

That is 6 that will not come out.

 

[gottaluvit]

If all of the glow plugs were not type/brand matched that's probably what did the others in.

They all need to have the same electrical characteristics or the ones with the lowest resistance will burn the hottest. Do you know what model the Wellmans were?

I put all the same in. A new 8 pack of 13Gs. The Wellmans were all 6a843g070.

 

[gottaluvit]

Don't get excited. It is not the end. Which 2 are stuck?

Cylinders 6 & 7 (2nd and 3rd from front on passenger side) are the ones that came out. The rest are stuck. I just cant believe they swelled from so few times of use.

 

[cpf240]

Well, I just tested every wire to the glow plugs and every one had the correct voltage. ... Tested the two with jumper cables on 24v and nothing on them two that came out...

What voltage did you see? And you tested the two glow plugs at 24v? The glow plugs run on 12v, not 24v. That is the reason for the resistor, to form a voltage divider network with the glow plugs to provide them with 12v.

 

[tim292stro]

I put all the same in. A new 8 pack of 13Gs. The Wellmans were all 6a843g070.

Sorry - mention of the Wellmans made it sound like you had 6 AC13s that were stuck and burned, and two Wellmans that came out and worked...

 

[rsh4364]

No offense to anyone,but this is a good example of why I did the GP resistor bypass,manual GP switch and run the 60g plugs.On my first 1009 the resistor ate 8 new GPs in a week.Now I know my GPs are getting 12v.

 

[gottaluvit]

What voltage did you see? And you tested the two glow plugs at 24v? The glow plugs run on 12v, not 24v. That is the reason for the resistor, to form a voltage divider network with the glow plugs to provide them with 12v.

I saw 24v at glow plugs. Yes, I tested at 24v, oops. No wonder it was instant. So is my controller bad?

 

[gottaluvit]

No offense to anyone,but this is a good example of why I did the GP resistor bypass,manual GP switch and run the 60g plugs.On my first 1009 the resistor ate 8 new GPs in a week.Now I know my GPs are getting 12v.

Sounds like my game plan

 

[tim292stro]

The controller should be isolated from 24V by the GP relay. The control lugs should have about 12V when the ignition is on and the relay goes "click" - in general if the controller is turning on the wait light and the relay goes click, I'd suspect that portion of your glow systems is running just fine.

The resistor bypass is a popular thing to do, the only real negative is that you imbalance the batteries during a jump since there's no 12V tap in the NATO port. If your alternators are working correctly, this should go away once you've run for a bit, but your upper battery will take a lickin' while the glow plugs run (since there would be no load on the upper battery while the lower battery draws >=1200Watts).

I saw 24v at glow plugs. Yes, I tested at 24v, oops. No wonder it was instant. So is my controller bad?

If you individually touched 24V to the glow plugs they're probably dead. 12V only for these. 24V is roughly half consumed by the ballast resistor to provide 12V to the glow plugs - but this presumes that the glow plugs are doing half of the work. If not the voltage will creep up to battery voltage as each successive glow plug burns out faster and faster (cascade failure).

 

[rsh4364]

Search cucv gp resistor bypass and weigh the options.This is how I wired mine.http://youtu.be/vCOWlJpnE8k

 

[rsh4364]

Sorry the vid. does exist but for some reason not linking.If you want to see search rsh4364 on youtube.

 

[Warthog]

A recap of how the stock system works. Simplified version (some steps left out, like starting the truck)

The stock glowplug in the CUCV are 12v versions.

1. 24v comes from the 24v buss bar to the large resistor pack and then to the GP relay
2. The GP controller card senses that the engine is cold and closes the ground circuit and allows the GP relay to energize
3. 24v now passes through the relay and goes to the individual plugs
4. With resistance of the large resistors and the individual plugs, the voltage drops to ~12v as the plugs heat up
5. As the plugs are heating up the controller card is reading the voltage and turning on and off the relay
6. After the engine starts the controller card will continue to cycle the plugs. This is the after glow.

Here is the issue. If the glow plugs are not with in spec it causes an imbalance in the system. Let's say that one plug fails. The resistance is now lower and allows a higher voltage to the other plugs. Since these plugs are really designed to operate at ~10v they are now seeing a higher voltage and are glowing hotter. Now second plug fails and the voltage goes higher. Then a third fails, a forth plug, etc, until finally the last plug sees the full 24v and dies in a painful death.

The speculation as to why GM choose this setup is to make the truck compatible with the other 24v trucks. It works great if everything is in good (not perfect) working order.

The HMMWVs run a true 24v GP system. They have treir own issues but burning up GPs is way down on the list.

There are members that have good luck with the stock system and those that have had issues and switch to the 12v setup and have good luck with that setup.

The only one that can make the decision on which way to proceed is yourself.

 

[Warthog]

Before replacing any of you plugs, verify that a "good" controller card is installed and the the system is working correctly.

There is a step-by-step procedure in chapter 2 of TM 9-2320-289-20 tech manual for the controller card system.

I say this because of the paper you found in the truck.

 

[gottaluvit]

A recap of how the stock system works. Simplified version (some steps left out, like starting the truck)

The stock glowplug in the CUCV are 12v versions.

1. 24v comes from the 24v buss bar to the large resistor pack and then to the GP relay
2. The GP controller card senses that the engine is cold and closes the ground circuit and allows the GP relay to energize
3. 24v now passes through the relay and goes to the individual plugs
4. With resistance of the large resistors and the individual plugs, the voltage drops to ~12v as the plugs heat up
5. As the plugs are heating up the controller card is reading the voltage and turning on and off the relay
6. After the engine starts the controller card will continue to cycle the plugs. This is the after glow.

Here is the issue. If the glow plugs are not with in spec it causes an imbalance in the system. Let's say that one plug fails. The resistance is now lower and allows a higher voltage to the other plugs. Since these plugs are really designed to operate at ~10v they are now seeing a higher voltage and are glowing hotter. Now second plug fails and the voltage goes higher. Then a third fails, a forth plug, etc, until finally the last plug sees the full 24v and dies in a painful death.

The speculation as to why GM choose this setup is to make the truck compatible with the other 24v trucks. It works great if everything is in good (not perfect) working order.

The HMMWVs run a true 24v GP system. They have treir own issues but burning up GPs is way down on the list.

There are members that have good luck with the stock system and those that have had issues and switch to the 12v setup and have good luck with that setup.

The only one that can make the decision on which way to proceed is yourself.

Thank you Warthog. After thinking for quite a while on this, I think I will keep it stock and just use wellman 070s. Apparently the 24v I am seeing at the glow plugs is correct. However, shouldn't I have seen it drop to(ward) 12v? Also, the wait light is going off real quick now with the Delco 13s vs. the normal 8 second or so illumination I got of it with the wellmans. Is that most likely the card or the failed 13s? I found a thread with a link to the section of the tm for the controller testing and have downloaded it and if the rain permits it, I will do that later today. I will also test all of the wellman's I took out (as well as these delcos once I get them pryed out) to see if, or how many of them may be good. I don't plan on reusing them, but want to know this for further understanding of what or what didn't go wrong.

 

[gottaluvit]

Also, I think that setup that paper in my glove box spoke of has been disconnected/removed. I noticed a wire tapped into the wide open throttle/transmission downshift switch by the gas pedal and it has a blade plug plugged into nothing and going nowhere. Looks like I will be able to work on the truck today sooner than expected so i will post results.

 

[tim292stro]

The wait light duration and separately the glow time (pre-glow, after-glow) depends on the ambient temperatures (most accurately the ambient temperature's effect on the temperature of the block/heads).

Yes the voltage supplied to the glow relay will drop to around 11.5-12.5V with correctly functioning ballast resistors and correctly functioning glow plugs (all of them).

Once you replace the glow plugs if you have a DMM/Multimeter, put the DMM/multimeter on your hood facing the driver's seat and connect the black lead to some grounded metal point, and the red lead to the cable connection on the glow plug relay from the ballast resistor. When you hit the ignition to run the first time you should see the voltage drop from 24-25V down to about half of that.

If it does not drop below 14V without the engine running, turn it back off. Pull the ballast resistor pack out of the circuit and check them for correct resistance.

 

[Warthog]

Have you watched the GP video in the Helpful Threads sticky? While it does not directly address your issues, it does help you understand how the system functions

http://www.steelsoldiers.com/showthread.php?62477-GP-Module-Theory-of-Operation

As far as the GPSS is concerned, I personally have never seen that setup.

 

[gottaluvit]

Thank you Warthog. After thinking for quite a while on this, I think I will keep it stock and just use wellman 070s. Apparently the 24v I am seeing at the glow plugs is correct. However, shouldn't I have seen it drop to(ward) 12v? Also, the wait light is going off real quick now with the Delco 13s vs. the normal 8 second or so illumination I got of it with the wellmans. Is that most likely the card or the failed 13s? I found a thread with a link to the section of the tm for the controller testing and have downloaded it and if the rain permits it, I will do that later today. I will also test all of the wellman's I took out (as well as these delcos once I get them pryed out) to see if, or how many of them may be good. I don't plan on reusing them, but want to know this for further understanding of what or what didn't go wrong.

Well, after much reading and a good bit of frustration trying to get stuck glow plugs out, I have decided it's time to convert glow plugs to 12v and I ordered some Delco 60Gs. It sounds like they have the least chance of swelling and at 12v I think that should extend their life. Gonna hook up a push button switch for the blue wire and pull the controller card if it seems like the wait light isn't staying on like it should.

Edit: I got all but three glow plugs out. One broke off and it just happens to be the #8. Yippee! Battery removal and injector removals tomorrow. I am sure the other two will break off too. Diesels are my newfound challenge!

 

[tim292stro]

Those (AC60G) and the Bosch Duraterm Inconel 601 parts. Both are self regulating and are less likely to swell (Bosch the least likely due to the shell alloy).

Again: The wait light and glow plug relay are not electrically connected!!! Just because the wait light went out doesn't mean it stopped glowing!!!

[EDIT:] I am in the process of building a switch for manual glow plug backup/troubleshooting. I still advocate the glow system being fixed as it is easiest to use when working right. [/EDIT]