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L99 7.3 4x4 auto. 132k miles, 6637 intake, exhaust and a PHP hydra chip are the only mods. I watch EGT and have never run it above 1200f.
The last time I drove my beloved 7.3 was 3 weeks ago. I took it for a 3 hour drive, mostly highway, unloaded. After pulling back into the driveway, I checked blowby for chits and giggles, since it had just been on a good long run. I check it a few times a year. The blowby looked great! Just a slight white vapor oozing out like normal. no pressure.
Fast forward 3 weeks, I knew it needed batteries, so i took the 2 old batteries in my car and got 2 new interstate 850cca batteries. Charged up the batteries and started the truck. It started even quicker than nornal and idled normal for about 10 seconds.
Then, a horrible racket and I shut it off. I thought I had left a wrench somewhere it had gotten into the clutch fan. I confirmed no obstructions and started it back up. It was knocking hard and well...the video shows the rest.
TL;DL version:
My 7.3 ran fine 3 weeks ago and now it has severe blowby and a hard knock/misfire after running only 10 seconds on new batteries.
I checked the oil while I was changing the batteries. It was 80% up the crosshatch area and has burned very little in the last 4k miles on this oil change.
I'm quite familiar with diesels, especially 7.3s and 6.0s. This is a new one for me. No warning, no signs of impending doom. Nothing. Just a loud, horrible metallic series of sounds, followed by blowby. I also checked the 6637 air filter. No holes, mice, etc, so nothing got sucked in.
Edit: the truck never left the driveway between it running normal 3 weeks ago and the video. I didnt even shift it out of park. The truck was shut off immediately after the video ended and haven't restarted it since.
WTF COULD POSSIBLY KILL A 7.3 LIKE THAT? The outside air temp was 95f. The truck hadn't been started in 3 weeks and other than slow-ish cranking before I swapped batteries, there were no symptoms of anything wrong. It still started in about 3 seconds. Even at 10f unplugged, it never took more than 5 seconds to start.
I am OCD about fluids, filters and maintenance. I never abused it, got it too hot, neglected it or anything like that. I've never pushed the limits with oil temps, EGT, or tuning. I tow in a 40hp tune and EGT stays below 1200f without effort. I drive unloaded in a 80hp tune. Nothing crazy.
I just dont understand how something like this could even happen, let alone on a well maintained 7.3. In the driveway. On a "cold" engine.
The first thing I would do is pull your valve covers and rattle some of the parts inside, everything should be tight and moving.....Push rods, valves, etc Listen for your racket and see if it's louder and on what side. Do a compression test also. although very rare, the guts on these trucks are very strong, but a blown Head gasket, Bent pushrod or valve has been documented. Not a Death sentence, but some repair is in you're future...…..
I have also heard of the occasional hole burned into the piston, or a Ring letting loose. but those are usually on Boosted motors.... A compression test should answer a least a few of those questions.
I got up for work at 4am and I wont be home from school until 9:30pm tonight. I wont be able to put a wrench to it until tomorrow evening at the earliest.
Now that I've settled down and reality has sunk in, I'm thinking something let loose. Between the horrendous blowby and the sounds it made, either something fell into a cylinder and beat up that piston or the piston/rod came apart. I feel like this is more than just a cracked piston or broken ring.
I've got a hostile neighbor that I wouldn't put vandalism past...something smells fishy. We'll see when I get the intake and valve covers off.
something fell into a cylinder and beat up that piston.
Originally Posted by brandonrr
The last time I drove my beloved 7.3 was 3 weeks ago. I took it for a 3 hour drive.. The blowby looked great!
I knew it needed batteries, so got 2 new interstate 850cca batteries. Charged up the batteries and started the truck. It started even quicker than normal and idled normal for about 10 seconds.
Then, a horrible racket...No warning, no signs of impending doom. Nothing. Just a loud, horrible metallic series of sounds, followed by blowby.
Cause and effect?
Or coincidence?
The dilemma of diagnostics.
I have found the most success going with cause and effect first, by always asking "What was the last thing I did, or the most recent change I made, prior to the fault?"
In your case, it sounds like you changed batteries to freshly charged twin 850's... after which you noticed quicker starting, and then a horrible racket like something fell into the cylinder.
Our glow plugs are only rated for 11 volts. Since the glow plugs continue to remain ON for up to 180 seconds after engine start, it is likely that the glow plugs were ON during that 10 second period after the engine started... being fed with perhaps a volt more than they were used to in recent years. If the glow plugs were already old and weak, then once the tips became heated from both within and without, from the higher voltage and the first few powerstrokes of combustion heat, their eminent failure might have been accelerated.
Over energized glow plugs can burn off their tips inside the cylinder.
I found an old post of mine that has photos illustrating what that looks like inside:
Originally Posted by Y2KW57
A long time ago, in a galaxy far, far away...
It is a period of dark civil screenlessness.
Rebel youth, lacking Snap Chat and Instagram, Xbox or Playstation,
wandered in the streets without cellphones, tablets, computers or video games to keep them occupied.
During the Battle with boredom, they could be found at the corner store... playing Pinball
Piston pelting pinball from a broken glow plug tip that broke off and bounced around in a Mercedes diesel.
Pinball in a Duramax
Pinball in a Nissan Patrol diesel (like a Land Cruiser, popular in Australia)
More Pinball Patrol, with the offending broken glow plug held next to a full length tip for comparison, with the damaged head in the background.
Pinball in a 7.3L IDI, with the replacement piston shown for comparison.
Pinball in a 6.0L Powerstroke, although the ball in this case might have been a blown off injector tip rather than a glow plug tip. Here's a tip: coulda been a rock for all it matters. Any hard object banging around in the cylinder is going to do some damage in the brief the time it takes between hearing a funny sound to reaching for the key to kill it.
Headside of that game of pinball in the 6 liter. Damaged valve and head.
GAME OVER!
This isn't a definitive diagnosis. It merely illustrates a method of diagnosis similar to an accounting convention used for figuring taxes... LIFO = Last In First Out.
Looking at the last thing you did (installed new and freshly charged batteries) , and the immediate result that followed (metallic sound as if something fell into a cylinder), and considering this sound as you described it in the instant that it happened in 10 seconds following initial start with the new batteries (which is a different sound than the audio in the video taken after the initial shut down)... suggests a glow plug tip pinball event as a possibility.
The previously posted recommendation still stands as the best way to determine if this cause and effect is the case, or whether there is some other coincidental event at play. Once the valve covers are off, following a visual inspection, the next thing to pull is all 8 glow plugs. If all 8 come out in tact, then you can rule this cause and effect out. But if you find yourself pulling out glow plugs of different lengths, after extracting all parts stuck in the threads of the head, and after reassembly of the glow plug pieces still find that one or two plugs measures up short, weill, then you'll know which cylinder if you keep track of which plug came from where.
I think you hit the nail on the head. It fits. the knock/miss I heard after restarting was nothing compared to the initial horror. The stronger, freshly peak charged batteries probably finished off a weak glow plug and it played pinball. GAME OVER. Just my luck.
This sucks, but at least I know what to check first tomorrow when I can work on it.
Now I gotta figure out how to proceed from here. There's no way that engine will be rebuildable. Unless I can find an engine somewhat cheap, this truck isn't going anywhere for a while. I have at least 7 good injectors and plenty of spare parts now. I dont even care if it's a 300k mile replacement engine at this point as long as compression is good and isnt too rough overall.
Yeah you got a problem there for sure. The glow plug idea is where my money is. I don’t think it is a real common failure but it does happen. Cheaper non OEM plugs often get the finger pointed at them.
Cause and effect?
Or coincidence?
The dilemma of diagnostics.
I have found the most success going with cause and effect first, by always asking "What was the last thing I did, or the most recent change I made, prior to the fault?"
In your case, it sounds like you changed batteries to freshly charged twin 850's... after which you noticed quicker starting, and then a horrible racket like something fell into the cylinder.
Our glow plugs are only rated for 11 volts. Since the glow plugs continue to remain ON for up to 180 seconds after engine start, it is likely that the glow plugs were ON during that 10 second period after the engine started... being fed with perhaps a volt more than they were used to in recent years. If the glow plugs were already old and weak, then once the tips became heated from both within and without, from the higher voltage and the first few powerstrokes of combustion heat, their eminent failure might have been accelerated.
Over energized glow plugs can burn off their tips inside the cylinder.
I found an old post of mine that has photos illustrating what that looks like inside:
This isn't a definitive diagnosis. It merely illustrates a method of diagnosis similar to an accounting convention used for figuring taxes... LIFO = Last In First Out.
Looking at the last thing you did (installed new and freshly charged batteries) , and the immediate result that followed (metallic sound as if something fell into a cylinder), and considering this sound as you described it in the instant that it happened in 10 seconds following initial start with the new batteries (which is a different sound than the audio in the video taken after the initial shut down)... suggests a glow plug tip pinball event as a possibility.
The previously posted recommendation still stands as the best way to determine if this cause and effect is the case, or whether there is some other coincidental event at play. Once the valve covers are off, following a visual inspection, the next thing to pull is all 8 glow plugs. If all 8 come out in tact, then you can rule this cause and effect out. But if you find yourself pulling out glow plugs of different lengths, after extracting all parts stuck in the threads of the head, and after reassembly of the glow plug pieces still find that one or two plugs measures up short, weill, then you'll know which cylinder if you keep track of which plug came from where.
Ummm,, Wow..
That is why I am here , never stop learning
Sure enough, it's got autolite 1111 plugs in it. Sure enough, cylinder 7 ate a glow plug tip. The plug came apart in 3 pieces. The tip is probably in the exhaust or the oil pan. The body of it was still in place, but the core of it was loose from the body, only held in place by the wire.
The actual blowby is likely less severe than the video shows. it was leaking compression straight into that valve cover through the hollow glow plug body.
Anybody know of a boroscope small enough to fit through the glow plug hole? I'll also be doing a compression test. I'm hoping the carnage isnt too severe for a rebuild. The engine was in excellent shape before this happened. I think might be worth spending a bit more to keep this one going vs tossing in a higher mile engine.
Sure enough, it's got autolite 1111 plugs in it. Sure enough, cylinder 7 ate a glow plug tip. The plug came apart in 3 pieces. The tip is probably in the exhaust or the oil pan. The body of it was still in place, but the core of it was loose from the body, only held in place by the wire.
The actual blowby is likely less severe than the video shows. it was leaking compression straight into that valve cover through the hollow glow plug body.
Anybody know of a boroscope small enough to fit through the glow plug hole? I'll also be doing a compression test. I'm hoping the carnage isnt too severe for a rebuild. The engine was in excellent shape before this happened. I think might be worth spending a bit more to keep this one going vs tossing in a higher mile engine.
Dude, that just sucks!!! I'd do the same if it were me. Replace all GPs with Beru only. This is why every 7.3 I have bought I go through the day I get it home and check all the glow plugs because I have had two trucks where I have found Autolite plugs in them.
Maybe test that cylinder or maybe not. I would replace all the glow plugs and then run it with the valve covers off and watch everything and listen to it because you can pull that glow plug right away and compression test it after that, if you feel the need. A new glow plug may fix your problem at least long enough for you to run the engine longer while you decide what to do for a rebuild or just go with it.
07-28-2019, 09:32 PM
