How would that have caused the piston damage? I have seen hydrolocking cause flattened or spun bearings and bent or broken connecting rods, but never make the pistons and combustion chambers look like they’ve had an air hammer taken to them. Water in the crankcase could cause bearing damage, but would have to be in the cylinders or intake for it to actually hydrolock the engine.
Just throwing something out there. The pistons and cylinder walls look like they’ve been hammered?
That usually points to foreign objects being swallowed; nuts, bolts, etc.
The valves are much harder material than the cylinder walls, pistons, and the vast majority of nuts and bolts so that could explain why the valves are relatively clean.
I’ve seen a couple of engines (including one VW Beetle that belonged to me) that suffered sabotage. One of them was a Corvette small block in which someone had thrown a 1/2" nut into the carburetor. That one nut worked itself into the cylinder and bang; broke a piston right in half.
Just wondering if some comedian may have dropped a few nuts into the intake tract. Run it a while and eventually the nuts (especially if they’re 1/4") could have worked themselve past the intake valve and then voila; instant destruction.
If this is suspected I think I would be tempted to yank the catalytic converter, dump it out, and see if there is any expelled, mangled metal in there.
If there is, then it’s time for a serious analyzing of relationships.
In my case, the guy who did my VW in (flat washers) wound up in prison by the time I figured out what happened. One of those “work release boys”.
That is an interesting theory. It happened right before my wife and I moved away from some neighbors who literally HATED us, especially my wife, for no reason, and the Grand Am was actually my wife’s first car that she loved with all her heart. I built that car for her as an engagement gift. It was abandoned at the shop by a customer who didn’t want to fix it, so he left the keys and title behind. It had a broken ball joint and had been wrecked before it came to a stop. She saw the sporty little coupe, with it’s white paint, blue racing stripes, custom wheels and dual exhaust (which was dragging the ground at the time) and just fell in love with it. I bought an identical parts car (minus the racing stripes) with a blown motor for $50, fixed the collision damage, ball joint, cv shaft, brakes, exhaust system, and everything else that was wrong with the car, and gave it to her. I wouldn’t put it past those sickos to do something like that to her beloved Grand Am, especially since the interior hood release didn’t work. I got lazy with that one and used a piece of wire coathanger through the grille to open the hood. Whether it was a malicious act or not that did the car in, we got our use out of it. We drove it for two years and 25,000 miles, got 34 mpg out of it at 80 mph going to Denver, CO and back (over 2000 miles round trip), and it only broke down once for a dead fuel pump (and shame on me, I knew it was going and waited for it to die before I replaced it, for only $60 and an hour and a half of work). By the time it did this, I had only put a total of about $700 into the car, including maintenance, over two years and 25,000 miles. Can’t beat that, even though the floorboards mysteriously filled with water every time it rained and there was nary a weatherstripping leak to be found and no wind noise, even in excess of 80 mph. BTW, my wife is very happy with her replacement vehicle, a 2006 Grand Caravan.
EGR not working causes high cylinder pressure and temperatures. Use of too low octane fuel. Check surviving pistons for micro-fractures.
Check fuel injectors for flow rate and patterns.
The backfire into the intake blew the pieces of aluminum into the intake.
ok, fascinating theory about sabotage, but mark, did the sickos have the necessary knowledge? What ok describes is not rocket science, but it does require some automotive knowledge.
After some more thought, I’m more and more convinced you were the victim of sabotage. The peening on the piston tops is not an indication of a severe pre-ignition rattle but the sign of metal banging on metal.
Piston damage caused by severe pre-ignition not only takes a while but the piston appearance is different. With pre-ignition the piston will erode around the edges and may even have the appearance of melting in spots.
Even 5 seconds of running with a nut or washer in the cylinder can peen a piston to oblivion. At some point if a nut or washer happens to stand on end and get wedged between the piston and valve then the piston is going to lose.
In the case of the VW of mine that I mentioned, this was a fresh engine on a project car. It ran fine for about 20 seconds before it started rattling and quit.
A tear-down revealed peened and now cracked pistons on 2 cylinders and one piston still had a nut embedded in it.
(And it wasn’t even a metric nut but a badly mangled 5/16 NC nut)
In the case of the Vette I mentioned, I saw this one after it was torn down and it also had a nut embedded in the piston top. The entire top of the piston was peened to death and suffered cracked ring lands all the way through.