Engine teardown adventure

IDIBRONCO

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and managed to break #7 because there's a sharp lip here, and the oil supply ring got hooked on it, bent and cracked the guide for the piston.
That's not surprising. I couldn't quite see the number on the piston, but I think there's an above picture of cylinder #7 with the piston still in it. There's one BIG ridge in that cylinder. To me, that looks like a lot of miles or dirt being sucked in through the air filter. If that's the only cylinder with that bad of a ridge, my only guess would be that the injector may have been leaking for a long time and got that cylinder too hot. Maybe that could have made the ridge somehow?
Seems like only half the bore has this sharp lip. Weird.
Not really if you consider the way that the "V" engines work. The reason why inline engines, Cummins included, last longer than a V style engine (usually) isn't because they're a superior engine, it's due to cylinder wear. In an inline engine, the pistons move up and down with minimal side pressure on the cylinders. In a V style engine, the pistons put more side pressure on the cylinder walls that are the farthest away from the crankshaft. This is because while the crank is rotating, it's pushing the pistons up and down, but also to the side since the pistons don't move straight up and down. This is why you only have a bad ridge on the side of the cylinder that's opposite from the crankshaft, toward the outside of the engine, not toward the center. The "waves" in your cylinders are different ring ridges. This makes me lean toward a very high mile engine. It also had the original style head gaskets due to the orange "stuff" left over on the block after you removed them. I didn't say that the head gaskets were the original ones. They could have been replaced with OEM gaskets in the past.
I'm not familiar with the processes that the liners are pressed out/in,
You're not quite grasping the concept here. These block and cylinders are one piece from the factory. Like a gas engine is made. They do not have liners from the factory like heavier duty diesel engines do. Sleeves are used to bring the cylinders back to the stock bore size when the cylinders have too much wear in them. What happens is that the machinist overbores the cylinders. Then the sleeves are press fitted into the block. The cylinders are bored to just slightly, maybe only .001", smaller than the outside diameter of the sleeves which is what keeps the sleeves in place. I believe that the sleeves actually have to be bored out a little bit to make them the stock bore size after they're installed. It's a more complicated process than replacing the liners in a heavier duty diesel engine.
 

WrenchWhore

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Man, that's a bummer that a piston got busted. NOOOOOOOOO!
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hacked89

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That's not surprising. I couldn't quite see the number on the piston, but I think there's an above picture of cylinder #7 with the piston still in it. There's one BIG ridge in that cylinder. To me, that looks like a lot of miles or dirt being sucked in through the air filter. If that's the only cylinder with that bad of a ridge, my only guess would be that the injector may have been leaking for a long time and got that cylinder too hot. Maybe that could have made the ridge somehow?

Not really if you consider the way that the "V" engines work. The reason why inline engines, Cummins included, last longer than a V style engine (usually) isn't because they're a superior engine, it's due to cylinder wear. In an inline engine, the pistons move up and down with minimal side pressure on the cylinders. In a V style engine, the pistons put more side pressure on the cylinder walls that are the farthest away from the crankshaft. This is because while the crank is rotating, it's pushing the pistons up and down, but also to the side since the pistons don't move straight up and down. This is why you only have a bad ridge on the side of the cylinder that's opposite from the crankshaft, toward the outside of the engine, not toward the center. The "waves" in your cylinders are different ring ridges. This makes me lean toward a very high mile engine. It also had the original style head gaskets due to the orange "stuff" left over on the block after you removed them. I didn't say that the head gaskets were the original ones. They could have been replaced with OEM gaskets in the past.

You're not quite grasping the concept here. These block and cylinders are one piece from the factory. Like a gas engine is made. They do not have liners from the factory like heavier duty diesel engines do. Sleeves are used to bring the cylinders back to the stock bore size when the cylinders have too much wear in them. What happens is that the machinist overbores the cylinders. Then the sleeves are press fitted into the block. The cylinders are bored to just slightly, maybe only .001", smaller than the outside diameter of the sleeves which is what keeps the sleeves in place. I believe that the sleeves actually have to be bored out a little bit to make them the stock bore size after they're installed. It's a more complicated process than replacing the liners in a heavier duty diesel engine.
Good points, when I read him say liners I thought he’s a diesel mechanic by trade and assumed he was just talking about sleeves but interchanging terminology. But if he’s working on medium and heavy duty with liners it would make sense he might have assumed.

Yes sleeves are typically interference fit + anerobic sealer.

What I was mentioning was with an 7.3 IDI (and I would assume 6.9 but can’t confirm) you want to use a “top hat” cylinder sleeve because non top hats even with interference fit and anerobic sealer tend to drop.

I should scroll through Justins videos to see if that’s what he’s using or if he’s not having an issue with dropping. In the cavitation TSB they directed sleeving but I don’t think they had flanged sleeves at that time.

Edited to add - if a machine shop does the install exactly correct than a non flanged sleeve is fine but it’s tough to find.
 
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Nero

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It does make sense what you're saying about wear. I do have a feeling this engine ingested a bunch of dust. I did buy it out of Madras, OR, which is a very dusty low population area. Plus there's practically no hone marks.

To further the discussion of liners, I mostly work on medium/heavy duty Cummins engines. All of them, minus the ISB (5.9 and 6.7 liters) have serviceable liners that are pressed in and out, and only use an o ring to seperate the oil and coolant areas of the engine. I had assumed that the 7.3 did something similar, due to liners and an install tool being available for purchase, but haven't torn one of these down that far yet. Most I've done previously with an idi is injection pump, water pump, injectors, lift pump and balancer.

Also as a note... No one talks about the ISV engines... The 5.0 Nissan used. Joke of an engine.
 

bulletpruf

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Holler if you need spare parts. I'm combining two 7.3's to make one 7.3 IDI turbo and I'll have some leftovers.
 

IDIBRONCO

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I mostly work on medium/heavy duty Cummins engines. All of them, minus the ISB (5.9 and 6.7 liters) have serviceable liners that are pressed in and out, and only use an o ring to seperate the oil and coolant areas of the engine.
I've done that on a 6-71 Detroit and they use a similar style of liners.
 

Nero

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Yeah it's pretty common for industrial heavy duty engines. CAT's use them too on their bigger engines.
 

Nero

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Meant to update this yesterday, but got sidetracked with other things, trying to restore a highly rusted cast iron pan my neighbor left outside for a decade.

I cleaned up one of the heads a little, and found it has two cracked injector cups. I stopped cleaning after the two, all may be cracked.
So between the heads needing done and the block needing cut, sounds like I should scrap this engine. I don't know. On average how much does it cost to bore one of these out and redo the heads? I know injector cups are a little hard to come by right now.
 

IDIBRONCO

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I don't know much about the heads, but for the boring, it varies from shop to shop. You'll just gave to call around to get some idea on local prices.
 

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