Yes, It's magnetic.
I'm betting blown head gasket. Sounds like mine, plus leaking coolant.
Pull the muffler off if it has one. Pull the air cleaner off. Pull the belts off or loosen - process of elimination. Crank it with the fuel off. If it pops, clangs, bangs, chuffs, poofs, anything other than smooth, fast, even cranking, something in the engine is mechanically broken or head gasket blown, something internal/major. Then try it with the fuel on.
EDIT: Also pull the valve covers and see what the valves are doing.
If you can get it running, crack the injector lines one by one and each should cause a miss. CAREFUL, skin-piercing high pressure fuel!