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One I took out and apart today. Guy bought this pickup only half a dozen months ago. Newer engine which turned out to be not the original but rebuilt at some point. I'm replacing it with a good used engine. There is a valve head stuck in this piston (#6) and a large crack in the cylinder wall.
You probably can't tell immediately why these valves are broken/missing, but the clues are there.
Of course, when there's a catastrophic failure in one cylinder, crap bounces between the adjacent cylinders through the intake and exhaust ports. #8 (last picture) also has a split cylinder wall at about 1:30 like #6.
Thankfully all of the pistons protrude from the deck by the same amount so I am hopeful that none of the rods are bent. The block is obviously garbage because based on others I have changed out, the block is likely cracked all the way through the main webbing and cam journals......based on the tuning that came off of it.
I have taken apart a lot of these things and to be honest, I'd say that a majority of them out there have had some sort of piston-to-valve contact at some point in their lives based on the few I've seen. You can see that there are witness marks on all of the pictures of pistons above but they're not bad and really only visible through the camera lens and flash; one has to look pretty darn hard to see them with the naked eye. I've seen MUCH worse with no valve damage.
Yes, this engine has been run hard. Hell, the passenger side turbine inlet pipe was deformed from heat and drive pressure. Then there's the tuning......[insert nuclear explosion emoji].
Here's another clue. As some of us know, the heads are identical from side to side (there is no "left" or "right" cylinder head) when it comes to the actual casting. Knowing that, I have set both heads side by side in a way that they should appear identical (RH head on its front and LH head on its rear). Keep in mind that this engine was rebuilt. What do you see?
Starting fluid sounds very possible, but giving the info about the cooked turbine inlet pipe and tuning, does anyone still run propane injection anymore?
Hmmm, #4 is the one missing an intake valve head and has a mangled exhaust valve. 5, 6, 7 and 8 look okay. 1 and 2 are out of shot. Closeup of #4 valves shows broken intake valve stem and rather clean intake port. My guess is injector failure on #4 leading to fuel starvation and possibly nitrous injection?
First thought was broken glowplug tip got caught between broken valves, or the misshapen injector hole. Then the second set of pictures got a different train of thought.
Maybe camera angles, but valves look like different sizes. Bigger on the left and dimpled in center. Is 1 an OBS 7.3 head?
Cant really tell by the pictures but are the valve seats missing on the second picture from the first post? Also looks like valve float took place by either boost or over revving the engine say manual trans? Also looking at the heads they appear to have two holes one for the glow plug and the other???
The intake and exhaust valves in a 7.3 are exactly the same size but they're made out of different material. The Machine Shop who rebuilt the engine installed intake valves in the exhaust ports on the left hand head. One of them decided they couldn't take the heat anymore and number 6 won the prize.
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