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5.7 blowing smoke and loud knock at high rpm

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Old Yesterday, 02:32 AM
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Default 5.7 blowing smoke and loud knock at high rpm

Hello all. This is my first thread on here but have read many that have helped. Hoping you all can help me today. I bought an '03 1500 4x4 Laramie with the 5.7 hemi. It ran, but barely. Once I trailered it home and looked closer in the daylight, there wasn't any oil in it. I filled it and now it smokes and knocks loud at around 3k rpm. It barely idles and absolutely no power at any range. The girl I bought it from said the truck had been put on its side. She also showed me the print out from an O'Reilly scan. It said the MAP sensor needed replaced, fuel injectors 5 circuit open, injector circuit cylinder 6, and fuel system 1/1 rich. I assume there is alot going on, but the knocking and smoke have me concerned the most. From what I've seen on other threads I will do a compression check tomorrow. If anyone has any ideas I would be eternally greatful.
 
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Old Yesterday, 07:32 AM
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If it ran for any appreciable time without oil..... rings and bearings are going to suffer. If it is knocking already, that's only gonna get worse. Time for a different motor, or a rebuild.
 
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Old Yesterday, 08:51 AM
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Thank you for the insight. While its not good news, it is what i figured and was afraid of. I hoped that with the knock and smoke only showing up at around 3k rpm that maybe it wad a valve spring or something of that nature. Wouldn't the knock sensor have kicked in and put it in limp mode? Just no telling how long she ran it with no oil. I plan to do a compression check today.
 
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Old Yesterday, 03:13 PM
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Default Valve seals?

Well, ..... more bad news. I put air pressure in cylinder 1 and its not pressurizing. Most of the air comes back out the oil filler tube, but there is a very small amount that also comes out the dipstick tube. My undereducated assumption would be that the valve seals are gone in this cylinder (or worse, cracked head). Any tests you may know of to see if it is just the seals or hole in the piston? Any other suggestions?
 
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Old Yesterday, 03:56 PM
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If you are getting it out the oil fill, that goes directly to the crank case, same as the dipstick tube, as the oil fill is larger, that's where most of the air will go. (path of least resistance) Either the rings are REALLY bad, or you have a hole in the piston.
 
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Old Yesterday, 05:19 PM
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Originally Posted by HeyYou
If you are getting it out the oil fill, that goes directly to the crank case, same as the dipstick tube, as the oil fill is larger, that's where most of the air will go. (path of least resistance) Either the rings are REALLY bad, or you have a hole in the piston.
That's what I was afraid of. It sounds like I need to do a complete engine swap. There goes the pocketbook. Thank you HeyYou for the respond.
 
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Old Yesterday, 06:55 PM
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Originally Posted by RLHawk
That's what I was afraid of. It sounds like I need to do a complete engine swap. There goes the pocketbook. Thank you HeyYou for the respond.
The bearer of bad news should keep one foot in the stirrup.

Maybe just throw a used motor at it, see how the rest of the truck is, once it runs reasonably well.
 
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Old Yesterday, 09:54 PM
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Default Sound advice

Originally Posted by HeyYou
The bearer of bad news should keep one foot in the stirrup.

Maybe just throw a used motor at it, see how the rest of the truck is, once it runs reasonably well.
HeyYou, that us some soumd advice. I'm already in the process of locating one at the local pull and save. They're talking $250. Maybe put a rebuild on it while I have it out. Put a few minor upgrades. Definitely keeping a foot in the stirrup. As I mentioned, I was once a GM fan. I have a '95 1500 4x4 that I rescued. Now, I've become a Mopar fan for sure. Thanks for the help, HeyYou.
 
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Old Yesterday, 11:31 PM
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Default Crank case pressure?

Originally Posted by RLHawk
HeyYou, that us some soumd advice. I'm already in the process of locating one at the local pull and save. They're talking $250. Maybe put a rebuild on it while I have it out. Put a few minor upgrades. Definitely keeping a foot in the stirrup. As I mentioned, I was once a GM fan. I have a '95 1500 4x4 that I rescued. Now, I've become a Mopar fan for sure. Thanks for the help, HeyYou.
As I sat here pondering, it made me wonder, wouldn't a hole in the piston put a bunch of air/fuel mix I. The crank case and ignite it? I had an old Blazer with a 350 do that and it blew my valve covers clean off the truck (they were spiffy aluminum covers). I would also expect to see pressure build up in the oil filler and dipstick tubes. Maybe I'm overthinking this and just need to send a bore scope down the plug hole. Sorry for the drama.
 
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Old Today, 09:10 AM
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Havin' a look with a bore scope sure won't hurt anything. But, either way, that engine is toast.
 



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