SOLVED! The same glow plug constantly roasting mystery..

Unfortunately when you pull the head you may find significant damage to the piston after eating all those glow plugs, the real problem is if the damage is close to the outsides of the piston crown indicating that the ring lands have been collapsed seizing the top ring, it is somewhat like Pandora's Box..

87cr250r said:

Good engines will have good compression regardless of temperature. Testing warm is more of a salesman gimmick to convince you to buy a weak engine. Especially in the case of a diesel engine good compression is most important when the engine is cold. Lower cranking speeds due to injectors in the hole or cold oil shouldn't have a huge impact on your compression number. If the number is lower during slow cranking it indicates leak down.

Testing an engine hot is like dumbing down the test so a bad student can pass it.

Click to expand...

This is kind of how I felt about it. I get that things expand as the engine heats up and that the engine is designed to operate with everything expanded so there *should* be lower compression when cold, but I guess what I was testing for was how deep in the hole was I? A cold test would give me that worst case scenario.

Also I'm not sure how someone would be able to warm up the engine and then maintain that temperature while removing all 8 plugs and conducting the test. I'd think that the engine temperature would have cooled significantly from the time you tested the first cylinder till the time you got to the last unless you were REALLY hustling and had great access to both sides of the engine. Particularly since each cylinder test you essentially have the other 7 cylinders pushing air through them. I suppose that's why they have you testing through the glow plug hole.. faster to get to than the injector holes, but unfortunately my "universal" Diesel compression tester adapters are too fat to slide in my injector holes. I'd be curious if there's a pressure difference testing between one and the other since the glow plug appears to be kind of "pointed" at the window of the pre cup. Pressure is probably pressure tho.

I ran out of time and daylight to do another compression test yesterday to see if I could get better results. I'm still confused as to why a cylinder with lower compression isn't burning up glow plugs but a higher cylinder is. Before I take the intake off I'll get in there with a scope and see if I can get eyes on what the top part of the operation looks like.. I may end up just saying to hell with it and replacing the engine all together.

Mogman said:

Unfortunately when you pull the head you may find significant damage to the piston after eating all those glow plugs, the real problem is if the damage is close to the outsides of the piston crown indicating that the ring lands have been collapsed seizing the top ring, it is somewhat like Pandora's Box..

Click to expand...

If i could get my scope positioned to peek through that pre cup window I should be able to get a look at the piston, shouldn't i? I might try that tomorrow afternoon. If that piston is jacked I think that'll be game over for this engine.

Humpty said:

If i could get my scope positioned to peek through that pre cup window I should be able to get a look at the piston, shouldn't i? I might try that tomorrow afternoon. If that piston is jacked I think that'll be game over for this engine.

Click to expand...

That window is rather small, not sure how well you can see the piston, the piston can sustain damage and still be OK, it is the area around the circumference of the piston crown directly above the ring lands that you would be concerned with.
Replacing a piston is not too much work after the head is removed, at least compared to how much work it is to remove/replace the head.

You have a cracked pre-cup, and very poor compression numbers. Fixing the engine would seem to be a fool‘s errand.

The biggest bang for the buck would be replacing the engine. That would also probably work out to be cheaper.

TOBASH said:

You have a cracked pre-cup, and very poor compression numbers. Fixing the engine would seem to be a fool‘s errand.

The biggest bang for the buck would be replacing the engine. That would also probably work out to be cheaper.

Click to expand...

I think maybe i’ll replace the startbox and upgrade to quality U.S. made glow plugs and be ok.

Your problem is an odd ball.

In most cases, replacing glow plugs and pcb/EESS is the textbook way to go.

I feel bad for you BUT you can now upgrade to a turbo GEP.

TOBASH said:

Your problem is an odd ball.

In most cases, replacing glow plugs and pcb/EESS is the textbook way to go.

I feel bad for you BUT you can now upgrade to a turbo GEP.

Click to expand...

Follow the data and not the trend. Not sure any textbook or TM suggests swapping out a start box because one glow plug bakes repeatedly. Multiple failures of the glow plug in the same cylinder was never going to be resolved with a start box or a “higher quality” glow plug. I came here looking for real, intelligent diagnostic advice and eventually got some.. after being chastised for ignoring a rubber stamp, knee jerk diagnosis.

A wordsmith, people looking at your thread and giving suggestions to a probable cause become the badguy. I will say what works for me may not work for you. You decide to pick words instead of observing the content of the post.

I quote said that I prefer Delco glowplugs, never said that was cause or cure did I? Then you passively aggressively suggest that you are smarter than anyone here who have been working on equipment for decades.

As far as pulling out a manual, why not read in manuals on how to conduct compression tests and the symptoms of the information that is being collected to determine the condition of each cylinder, or its adjacent cylinder, headgasket. Would save some time.

We are hear to help and maybe I am reading this wrong. Your problem too many is not an ordinary problem, its not a recognizable problem as to most it seems that it is an impossible problem as many have never seen a melting glowplug on just one cylinder that operates on its own.

After you chastise a very informative knowledgeable member for helping you I should have looked to other threads to read but thought I could give information on what to look for. As many here thought the same.

Good luck to you and your problem and have a swell day.

cucvmule said:

A wordsmith, people looking at your thread and giving suggestions to a probable cause become the badguy. I will say what works for me may not work for you. You decide to pick words instead of observing the content of the post.

I quote said that I prefer Delco glowplugs, never said that was cause or cure did I? Then you passively aggressively suggest that you are smarter than anyone here who have been working on equipment for decades.

Click to expand...

SEVERAL responses instructed to replace the glow plugs with QUALITY glow plugs. That does not resolve my issue. This issue began with the truck roasting a "quality" glow plug. I also was told the start box was suspect. That diagnosis simply did not match the symptoms. I've barely been working on these trucks for 20 weeks, let alone 20 years. What you read as "passively aggressively suggesting that i'm smarter than anyone here" is simply frustration that I came here looking for ideas from people with vastly more experience with these trucks and what I encountered, largely, were people who start off with replacing $800 start boxes and choosing $80 "quality" glow plugs when anyone with even a rudimentary grasp of how these trucks work would know NEITHER would be responsible for a glow plug frying in the same cylinder 4 consecutive times with all the other glow plugs remaining unaffected.

cucvmule said:

As far as pulling out a manual, why not read in manuals on how to conduct compression tests and the symptoms of the information that is being collected to determine the condition of each cylinder, or its adjacent cylinder, headgasket. Would save some time.

Click to expand...

I did pull out a manual. I printed several thousand pages of manual. None of them led me to a resolution. That's why I came here seeking the council of persons "who have been working on equipment for decades". I eventually *did* get some helpful advice and thoughtful consideration.

We are hear to help and maybe I am reading this wrong. Your problem too many is not an ordinary problem, its not a recognizable problem as to most it seems that it is an impossible problem as many have never seen a melting glowplug on just one cylinder that operates on its own.

cucvmule said:

After you chastise a very informative knowledgeable member for helping you I should have looked to other threads to read but thought I could give information on what to look for. As many here thought the same.

Click to expand...

Are you talking about the fellow who suggested that the start box was "sending more juice" (or words to that effect) to one glow plug and me simply stating that's not how electricity works?

Wow.

The foregoing comments point up how organizations and clubs can be damaged and even fall apart. How would they look to a new visitor browsing the forum who may simply be interested in becoming part of a group of people with a common interest in military vehicles? Would your comment (that's an "editorial" your) be more or less likely to impress someone to return or even to acquire a vehicle?

How many of us know former club members or hobbyists who have left the fold over hard feelings? My guess is everyone reading this post. We should always be building, building, building.

However frustrating a particular problem may be, this hobby should be fun. However frustrating a particular problem may be, if it is not fun, then don't do it. It sounds trite, but life really is too short to spend pissing (or seem to be, whether or not intended) on people who should have the benefit of the assumption of good intentions when trying to help.

We may not always be right. In some cases, we may be spectacularly wrong. Most of the time, as in this case, someone will come up with something that works. Rather than casting aspersions on the intentions or knowledge level of the participants (who should be taken as your friends), it's more productive and fun to give constructive feedback on what's working or not working for you.

Bottom line, it's your truck to do with as you please. If there's a possibility, however remote, that you think you may receive an answer that you won't like, then, please, don't ask the question.

Humpty, you just fell from your wall.

I’m not interested in your self righteous attitude.

YOU came to us. YOU asked for advice. YOU then spit at those of us trying to help.

When you ask for advice, it is a request for ideas and not a demand for a guaranteed road map to success. After-all, we are all spread out across this World, and none of us has access to your rig. We all made good faith efforts, that you shat upon.

I don’t relish using the “ignore” feature, but I think in this case it is warranted.

I will no longer respond to this thread. Say what you want, I won’t work with or respond to the self righteously rude.

ODAddict said:

Bottom line, it's your truck to do with as you please. If there's a possibility, however remote, that you think you may receive an answer that you won't like, then, please, don't ask the question.

Click to expand...

I’d add that if you think the answer you’re about to give, however remote, is just flat out wrong then please don’t get your panties in a wad if someone points it out.

I’ll invite you to re-read the thread. It wasn’t that I “didn’t like” an answer. It’s that the answer was just flat out not a correct answer. My start box and glow plugs are fine.

My crime here is proving the grand poobahs assertion that my start box and/or Chinese glow plugs were bad was completely wrong. I’m “self righteous” because I didn’t accept his diagnosis as gospel. I dared question a guy with “20 years experience” and who “holds contracts”.

I only bother replying now because this COULD be a great resource for the community but it has kinda gotten the reputation of being an old boys club.

Learn something from everyone, follow no one, and watch for patterns.

The last question I asked here was about aftermarket mufflers.. and out came the peanut gallery with how there was no way a person could possibly do that.

Big thank you to the like.. three people who actually offered insightful advice. To the ones who got their feelings hurt when you offered flat out wrong advice and their disciples.. i’ll leave you to your echo chamber.

(lsigh)

For what it's worth, I'm fairly new to this forum. My experience, for some reason, has been very different from yours.

As to "an old boys club," my observation is that one can't reasonably aspire to become part of "an old boys club" if you're combative, confrontational, accusatory, just plain nasty, or are impatient with those who may know less than you. Perhaps you don't aspire--I don't say that you should. As for me, though, I think I can learn a lot from the "old boys" even if they are not always 100 per cent correct or are younger than I. That seems to be more the case with each passing moment.

Good luck with your truck, Mr. Humpty. I mean that sincerely.

ODAddict said:

(lsigh)

For what it's worth, I'm fairly new to this forum. My experience, for some reason, has been very different from yours.

As to "an old boys club," my observation is that one can't reasonably aspire to become part of "an old boys club" if you're combative, confrontational, accusatory, just plain nasty, or are impatient with those who may know less than you. Perhaps you don't aspire--I don't say that you should. As for me, though, I think I can learn a lot from the "old boys" even if they are not always 100 per cent correct or are younger than I. That seems to be more the case with each passing moment.

Good luck with your truck, Mr. Humpty. I mean that sincerely.

Click to expand...

Again, i encourage you to reread this thread as to when I was ever “combative, confrontational, accusatory, or just plain nasty.” After repeated slights on my choice Chinese glow plugs.. THAT ARE FINE I referred to someone sarcastically as “Captain America” for again suggesting “quality” glow plugs.. considering the very first glow plug that failed WAS A “QUALITY” plug.

Whatever. You seem like one of the decent level headed people here. There were a few others. An objective reread of this thread will recognize who is who.

I’m a guy who was excited about getting a truck, found this page and immediately became a supporting member and almost as quickly found that this just isn’t the place for me, and that’s OK. In my searching in the months since I’ve learned that I’m not the only one who has made that observation.

Thanks for the well wishes and I wish the same for you.

SOLVED!

Updating for the benefit of anyone else who may encounter this or a similar issue. What ended up being the culprit was injector lines 5 and 6 were reversed at the injector pump.

Firing order being 1,8,7,2,6,5,4,3 essentially cylinder 6’s fuel was getting blasted onto 5 prematurely.. collecting on the glow plug and eventually burning off, roasting the glow plug.. even with the glow plug completely disconnected from the glowplug controller.

I’d been told that by the previous owner that the pump had been “rebuilt” but then the truck had sat for a couple years afterward. I didn’t think to check the lines just because I assumed since they were custom bent that you couldn’t hook them up wrong. Evidently you can.

Humpty said:

SOLVED!

Updating for the benefit of anyone else who may encounter this or a similar issue. What ended up being the culprit was injector lines 5 and 6 were reversed at the injector pump.

Firing order being 1,8,7,2,6,5,4,3 essentially cylinder 6’s fuel was getting blasted onto 5 prematurely.. collecting on the glow plug and eventually burning off, roasting the glow plug.. even with the glow plug completely disconnected from the glowplug controller.

I’d been told that by the previous owner that the pump had been “rebuilt” but then the truck had sat for a couple years afterward. I didn’t think to check the lines just because I assumed since they were custom bent that you couldn’t hook them up wrong. Evidently you can.

Click to expand...

Sometimes it's the simplest thing. I had a similar issue with my M715. I had a misfire and couldn't lock it down. I finally decided to check the plug wires at the distributor and plugs 2 and 4 were swapped.

Glad you found it and thanks for updating us!

kendelrio said:

Sometimes it's the simplest thing. I had a similar issue with my M715. I had a misfire and couldn't lock it down. I finally decided to check the plug wires at the distributor and plugs 2 and 4 were swapped.

Glad you found it and thanks for updating us!

Click to expand...

For decades i’ve found old message board threads with folks experiencing similar issues as i’ve had on a wide range of products. More often than not the threads would die and there was never any resolution. I posted this issue recently in a fb HMMWV group and a random guy was like, “Are you sure your injectors are running to the right place on the pump?” and it was immediately a eureka kind of moment. How had I not thought of that? Seemed unlikely those steel pre-bent lines were connected wrong but it was a suggestion that absolutely matched my symptoms. I was actually seriously considering pulling the head on that side and replacing the IP. All this time it was just 5 and 6 swapped.. literally a 0 dollar repair.

Sometimes seemingly big issues have a simple solution. I hope my odyssey helps save someone else a ton of time in the future.