2003 Ford Focus SE2.0L SPI EngineAutomatic Transmission 145KPerfectly maintained since new!One of the pistons had snapped, yes the actual piston, it didn't mess up the walls, but I am hearing a LOT about these dropping valve seatsI intended to do an entire rebuild with a kit, but did it break BECAUSE of a droppedvalve seat?I don't know because I don't know what that isHelp is appreciated
Valve seat is the actual area on the head that the valve rests in when closed. Dropping a valve normally means that the keepers have come loose or a spring has broken and the valve has dropped into the cylinder. This was a common occurance when some one has modified an engine without upgrading the valve train especially in older engines.
I don't know if cars really have replaceable valve seats or seats that can come loose (maybe they do with aluminum heads). But if a valve contacts a piston for whatever reason the valve and piston can sort of disappear (ie, break up). How many miles are on the car, and if it has a timing belt, did you ever replace the timing belt at the recommended miles (not normally an issue for engines with timing chain). Many engines are interference engines which means that if the timing belt breaks and pistons keep moving, a piston can hit a valve. Although, we had a regular V8 engine do that (valve and piston disappear) with a car from the late 1960's (not sure of actual cause, we replaced it with a used engine).
highly unlikely , depends how the piston is broken often when revving too high the piston top will separate at a ring groove nothing to do with valve seats