jaluhn83
Full Access Member
Finally got to tearing my motor down this evening after having it sit all week while I had to work late..... I was expecting to fine a loose wrist pin but so far they all look fine. Instead I find this:
Not the easiest thing to see, but there's a section about 1/8" square from the crown down to the top ring land that has been ripped out of the piston and is stuck to the cylinder wall.
There's also some pretty decent scuffing on the skirt, but no no major damage to the bore or rings.
I'm somewhat baffled by what happened to cause this. My best guess is overheating, but it's interesting that none of the other pistons show any major issues. That head also has what looks like some pitting around the intake valve for that hole, not sure what that is or if it's even real - might just be carbon built up.
For a bit of background, this motor was rebuilt ~30-40k miles ago in 06. Originally the rebuild was a result of a major overheating incident (puked a freeze plug and dumped the coolant while at full throttle pulling ~18k gvw up tehacpi pass) causing cracked heads. At that point I had access to a full machine shop so a rebuild was natural. ~9 months later I got her back together and took off to my folk's house with the horse for spring break (~400 miles one way). The day before I headed back the truck developed a intake thumping that seemed to be a valve issue. Decided to go home anyway since I had to be back and she seemed to be running fine, plus I had little in the way of shop support there. Turned out the noise was a cracked rocker holding a valve open leading to a piston crashing, dropped valve and eventually the piston disintegrating. So we did another rebuild, but I was able to reuse the crank, bearings (all but that rod), one head, 7 pistons, etc. One side effect of this is that some of the pistons had slight damage from ingesting parts which you can see still in the pictures. Also, one of the pistons and rod was replaced.
Sometime over the past some years the truck developed a rattling noise that sounded similar to the normal diesel rattle. ~18 months ago I realize that it's loud and distinct enough to start getting worried leading to an exhaustive search for the source. The rattle sounded sort of like a valve train issue or bad injector so that was the original direction. It's not like anything I've really hear before. From below it sounded very metallic, but from above it sounded like it could almost just be normal diesel rattle. Wound up replacing the lifters and injectors and spend lots of time checking things out but never to any end. I did an oil analysis and it came back high in iron but reasonably normal for other metals. Finally I had a machinist listen to it when I was picking up some other parts and he said it was a loose wrist pin. This did seem to fit with the symptoms and the high iron results, and it certainly conceivable that when I replaced the one piston and rod on the 2nd rebuilt we failed to size the rod bushing. So the engine comes out.... and I'm totally wrong!
There's one significant overheating incident I can think of, but I don't think it got that hot. Sometime not too long after the rebuild, (07/08??) the screw holding the block heater in came loose causing a slow coolant leak that eventually turned into a faster one when the screw fell out on the freeway. IIRC, it got hot enough to cause the temp light to come on (which I have setup for 225, not the 241 stock) after which I limped another 1-2 miles to try and get home but under very light throttle. Didn't seem to hurt anything at the time, but from what I see it seems pretty evident that she got pretty hot internally. I also had a ongoing mysterious coolant loss for ~a year that would cause air bubbles to form in the heads (I think) under load and would cause it to get warm, but never over ~225 and I never really lost coolant. Never really did figure out a source of that - it acted sort of like a heat gasket but not really.
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Not the easiest thing to see, but there's a section about 1/8" square from the crown down to the top ring land that has been ripped out of the piston and is stuck to the cylinder wall.
There's also some pretty decent scuffing on the skirt, but no no major damage to the bore or rings. I'm somewhat baffled by what happened to cause this. My best guess is overheating, but it's interesting that none of the other pistons show any major issues. That head also has what looks like some pitting around the intake valve for that hole, not sure what that is or if it's even real - might just be carbon built up.
For a bit of background, this motor was rebuilt ~30-40k miles ago in 06. Originally the rebuild was a result of a major overheating incident (puked a freeze plug and dumped the coolant while at full throttle pulling ~18k gvw up tehacpi pass) causing cracked heads. At that point I had access to a full machine shop so a rebuild was natural. ~9 months later I got her back together and took off to my folk's house with the horse for spring break (~400 miles one way). The day before I headed back the truck developed a intake thumping that seemed to be a valve issue. Decided to go home anyway since I had to be back and she seemed to be running fine, plus I had little in the way of shop support there. Turned out the noise was a cracked rocker holding a valve open leading to a piston crashing, dropped valve and eventually the piston disintegrating. So we did another rebuild, but I was able to reuse the crank, bearings (all but that rod), one head, 7 pistons, etc. One side effect of this is that some of the pistons had slight damage from ingesting parts which you can see still in the pictures. Also, one of the pistons and rod was replaced.
Sometime over the past some years the truck developed a rattling noise that sounded similar to the normal diesel rattle. ~18 months ago I realize that it's loud and distinct enough to start getting worried leading to an exhaustive search for the source. The rattle sounded sort of like a valve train issue or bad injector so that was the original direction. It's not like anything I've really hear before. From below it sounded very metallic, but from above it sounded like it could almost just be normal diesel rattle. Wound up replacing the lifters and injectors and spend lots of time checking things out but never to any end. I did an oil analysis and it came back high in iron but reasonably normal for other metals. Finally I had a machinist listen to it when I was picking up some other parts and he said it was a loose wrist pin. This did seem to fit with the symptoms and the high iron results, and it certainly conceivable that when I replaced the one piston and rod on the 2nd rebuilt we failed to size the rod bushing. So the engine comes out.... and I'm totally wrong!
There's one significant overheating incident I can think of, but I don't think it got that hot.
Sometime not too long after the rebuild, (07/08??) the screw holding the block heater in came loose causing a slow coolant leak that eventually turned into a faster one when the screw fell out on the freeway. IIRC, it got hot enough to cause the temp light to come on (which I have setup for 225, not the 241 stock) after which I limped another 1-2 miles to try and get home but under very light throttle. Didn't seem to hurt anything at the time, but from what I see it seems pretty evident that she got pretty hot internally. I also had a ongoing mysterious coolant loss for ~a year that would cause air bubbles to form in the heads (I think) under load and would cause it to get warm, but never over ~225 and I never really lost coolant. Never really did figure out a source of that - it acted sort of like a heat gasket but not really.
