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| 1999 to 2003 7.3L Power Stroke Diesel 7.3L Power Stroke Diesel equipped Super Duty and Excursion. |
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#1
Wed, February 3rd, 2021, 09:43 PM
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7.3 Carnage.
I rebuilt a 7.3L for a guy about a year and a half ago. It turns out that the engine had been rebuilt ALREADY just before this guy bought it.
I'll post two pictures here and let someone take a crack at what caused the failure. This was a 1000% non-fixable block as you'll see. What was the root cause of the failure? Good luck. Winner gets.....well......to say he guessed the cause. 
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#2
Thu, February 4th, 2021, 01:47 AM
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Aren't the valves supposed to be in the Cylinder Head, not the top of the piston?
My initial guess would be bad seat pressure on the springs which caused valve float. Or possible, trying to run an exhaust brake which again caused valve float. As you indicated, that block is scrap at this point! 
__________________
Bill Cohron - The Mad Doctor   Power Hungry Performance - The ORIGINAL in Ford performance tuning... Since 1997! (678) 890-1110 www.gopowerhungry.com - Home of the Hydra Chip, Minotaur Tuning Software, and the new Orion Reflash System for Navistar! Bring back  Windows™ XP and 7.  Windows™ Vista and Windows™ 8 is a pain in my a$$!  Windows™ 10 is only slightly less annoying!  Windows™ 11 is garbage!  Much to my surprise, I'm actually quite enjoying Linux! 
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#3
Thu, February 4th, 2021, 08:31 AM
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Yes, the valves in that particular cylinder are supposed to be in the head, not the piston.
 However, they did not travel from their home due to any issue listed. A couple more pictures: Cylinder 6 was the initial failure and as you can see, the block is cracked at the 2 o'clock position in #6 (picture rotated 90 degrees counterclockwise) and cylinder #8 that ate some of the chunks (#6 wasn't selfish and decided to share), cracked the cylinder wall at the 2 o'clock position as well. That whole section of the block was BROKEN all the way to the lifter bores. The tuning that was flashed to the PCM long before I ever saw this thing...well...it was HOT. But that's not why it failed. The answer will be revealed a bit later but here's another hint: There is a reason the cylinder heads were pictured side by side and keep in mind that this engine was recently remanufactured. Last edited by cleatus12r; Thu, February 4th, 2021 at 12:39 PM.
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#4
Thu, February 4th, 2021, 04:10 PM
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Did they spin it too fast for too long?
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#5
Thu, February 4th, 2021, 08:55 PM
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Oh, it looks like the intake and exhaust valves are swapped on the one head.
__________________
Bill Cohron - The Mad Doctor Power Hungry Performance - The ORIGINAL in Ford performance tuning... Since 1997! (678) 890-1110 www.gopowerhungry.com - Home of the Hydra Chip, Minotaur Tuning Software, and the new Orion Reflash System for Navistar! Bring back Windows™ XP and 7. Windows™ Vista and Windows™ 8 is a pain in my a$$! Windows™ 10 is only slightly less annoying! Windows™ 11 is garbage! Much to my surprise, I'm actually quite enjoying Linux!
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#6
Thu, February 4th, 2021, 09:05 PM
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BINGO!
They are the same diameter and length. The seats are cut at different angles but they'll still seal. The problem? The margin becomes too narrow and the valve material is WAY different. The exhaust valve is an inconel alloy and the intake is something ferrous that is way less heat resistant. You win, Bill!
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