Looks like mouse nibbled pistons ?

Dedward

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Has anyone seen this? All the pistons on the left bank have the same nibbled top of the piston, right side is normal. I Pulled the heads because of blown head gasket and found cracks between two valves on this side.
Also all cylinders have obvious lobbing.
I am just going to throw the gaskets I already bought into it with a new/ junkyard head, cut my losses and run this truck as a ranch truck till it dies.
 

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u2slow

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That looks like an area melting from excessive heat. Corners/edges don't dissipate as well.
 

Dedward

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Thanks u2slow. That + the cracked head makes sense. It came with a banks and based on the overall wear in the engine the po drove it like he stole it. Probably never even glanced at the egt’s.
super disappointed by my experience with the 7.3. Looking for a 6.9 that I can swap parts and lightly build up. Have a Cummins that I love but it’s not 4x4 and that’s what I needed this to do work with.
 

u2slow

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Is it's a factory Tidi? These handle the heat and pressure of turbocharging better.

I daily drive a 2wd Cummins. A locking axle makes the possible for me, as most driveways are gravel or dirt, and long. The 4wd brute is for special chores.
 

Dedward

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No it’s not the factory turbo which I believe have ceramic coated pistons and larger wrist pins. So the damage is obviously a result of the added banks turbo. But they shortened the life span of these right off the bat by closing off four coolant passages. Probably cost the engines 100000 miles in lifespan.
My dually Cummins goes around the hills where live ok but I put a tank of water in the back. This time of year the road is powdery and hauling anything I need 4wd. I’ve got some stuff waiting at the bottom of the hill to haul up and my neighbor is getting annoyed. so this is just going to go back together in whatever condition it is and I will use it till I can get a better option
 

u2slow

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Extra fuel makes high temps even without a turbo. If it's just one cylinder, it could be a bad injector. Also check where the ring gaps are ending up... Maybe it's pushing oil in the area of the burn?
 

Dedward

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It’s the whole left bank of cylinders. I’m pretty sure more fuel makes a lower temp while lean burning makes higher temps. Turbos burn hotter because they create a more dense fuel air (more air/leaner) mixture, a bigger hotter charge per power stroke and that heats up the whole area beyond normaly manageable cooling. injectors have a metered amount of fuel they spray that can be varied mostly through messing with opening “pop” pressure but that is a very small variation and quickly effects spray pattern and timing. If they were bad injectors they would be not spraying right/ dripping fuel that wouldn’t be burning well. possibly getting by the rings and into oil where it can cause issues. I’ve seen people destroy their engines running veg oil when they don’t pay attention to their injectors. That stuff will gel the crankcase oil. I’m not going to pull the engine apart to check the rings. (It started fine before so it has adequate compression. Any gap big enough to push significant oil would show on compression. When I bought it it had 295-340 not awesome but fine.) the ring gaps on a diesel aren’t enough to leave a spot and that theoretical spot of oil would actually burn at a lower temp leaving a deposit from incomplete combustion.
 

IDIBRONCO

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Is it's a factory Tidi? These handle the heat and pressure of turbocharging better.
Not in this situation. The anodizing on top of the pistons doesn't go all the way to the edges. There's about a 1/4" wide ring all the way around the outside of the top of the pistons that are plain aluminum. They REALLY should have been completely anodizes on the tops.
which I believe have ceramic coated pistons
Only the tops of the pistons are coated and they're anodized, not ceramic coated.
But they shortened the life span of these right off the bat by closing off four coolant passages.
Right now is the perfect time to fix that issue. Remove the stainless steel plugs and then either run 6.9 head gaskets or you can punch small holes in the lower corners of the 7.3 head gaskets so that coolant will flow through. You don't want the holes to be very big. Wes said that he tried opening up the stock holes in the tabs for 6.9 head gaskets. It worked great until he was pulling hard with the truck. Then it actually ran hotter.
 

u2slow

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Throw away the gas-engine lean/rich thinking. More fuel is more heat. Turn up the pump, higher egts. Lube oil ingress can also make heat.

As for one bank running hot... I wonder about the water jacket and cooling.
 

Dedward

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Ah anodized, ceramic is interesting if really trying to push limits tho.
I was thinking just that about the 6.9 coolant mod but had ordered factory head gaskets already and the 6.9 have a triangular rubber coated gasket seal that I figured mattered with the coolant contact. So I wussed out and put it back together stock. Also I saw that the pistons come a couple sixteenths proud of the face of the block and thought that the 6.9 gasket being just slightly smaller might interfere.
I am not a big tuner guy, I like dependable efficient working power not crazy blow black smoke all over the road stuff. More fuel does not mean more power, with diesel the opposite. That black smoke billowing out of big tuner guys trucks isn’t power it’s wasted energy. The fuel air ratio of a diesel can lean out tremendously before you need to add fuel. But the temperature goes up, and you end up cracking heads and burning the edges of pistons. I prefer moderation.
 

IDIBRONCO

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I've been running 6.9 head gaskets on my 7.3 for over four years now and haven't had any issues.
 
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