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I've never heard of the 2.8 diesel before, and I've never owned or worked on a diesel car. This opinion is coming from experience on gasoline engines.
I don't think that a piston strike could destroy a con rod (that's what I assume happened). It takes a lot to break those-- think about it this way. My Dodge has a 2.5 liter, four cylinder engine that makes about 100hp. That means each cylinder is responsible for about 25 of those horses. One piston, pin and con rod for 25 horsepower. This is in an engine that has an 8.9:1 compression ratio or thereabouts. When you consider that diesels typically run 20:1 or higher, you get an idea of how much stronger the components are. The valves, however, aren't really that much more substantial in a diesel, because the only force on them that really increases is the force pushing them against their seats. So you have a stronger lower end hitting a top end without nearly as much strength in comparison to the relationship between bottom and top end in a gas engine. I have never heard of this happening in a gas engine. The only way I could really see it happening in any engine is if the face of the valve went into the cylinder and got stuck so it was taking up a substantial amount of room. Even then, the cylinder heads are much softer than the crank and connecting rods. I would think that the tendency would be to ram the sideways valve into the head. You'd see significant head, piston and valve damage, but I doubt you'd have damage further down.
I would be looking for another garage if I were you. It certainly sounds like the mechanic you have is doing sloppy, careless work. An engine that has had a piston strike needs to be carefully examined, particularly the head, valves, cam, AND cylinder bores. The engine needs to be gone through to make sure no pieces have come loose and ended up in the engine. That's what it takes, and I would be DOUBLY sure to make sure EVERYTHING in the engine is OK before releasing the vehicle if the piston strike resulted from poor work on my part previously, as it seems here...
I've never heard of the 2.8 diesel before, and I've never owned or worked on a diesel car. This opinion is coming from experience on gasoline engines.
I don't think that a piston strike could destroy a con rod (that's what I assume happened). It takes a lot to break those-- think about it this way. My Dodge has a 2.5 liter, four cylinder engine that makes about 100hp. That means each cylinder is responsible for about 25 of those horses. One piston, pin and con rod for 25 horsepower. This is in an engine that has an 8.9:1 compression ratio or thereabouts. When you consider that diesels typically run 20:1 or higher, you get an idea of how much stronger the components are. The valves, however, aren't really that much more substantial in a diesel, because the only force on them that really increases is the force pushing them against their seats. So you have a stronger lower end hitting a top end without nearly as much strength in comparison to the relationship between bottom and top end in a gas engine. I have never heard of this happening in a gas engine. The only way I could really see it happening in any engine is if the face of the valve went into the cylinder and got stuck so it was taking up a substantial amount of room. Even then, the cylinder heads are much softer than the crank and connecting rods. I would think that the tendency would be to ram the sideways valve into the head. You'd see significant head, piston and valve damage, but I doubt you'd have damage further down.
I would be looking for another garage if I were you. It certainly sounds like the mechanic you have is doing sloppy, careless work. An engine that has had a piston strike needs to be carefully examined, particularly the head, valves, cam, AND cylinder bores. The engine needs to be gone through to make sure no pieces have come loose and ended up in the engine. That's what it takes, and I would be DOUBLY sure to make sure EVERYTHING in the engine is OK before releasing the vehicle if the piston strike resulted from poor work on my part previously, as it seems here...