Engine knocking on drivers side top. Replaced front timing chain cassettes and put covers back on and started it up to have major noise on passenger side. Pulled #2 spark plug and it was mashed. Pulled engine out of vehicle and pulled head off to see cracked piston and one valve on that cylinder broken. Rear guide was also broken on timing chain. Very poor quality engine, although I had the same engine in Mustang with no issues other than 26mpg best mileage with manual transmission. Salvage yard engine put in with 4000 miles driven with no real issues. Mountaineer/Explorer max 20mpg highway auto transmission. German assembled engine not designed very well.