oddballcustumz

I purchased a 2005 form a guy it has 103k miles on it and when it's running you hear a loud knocking type sound coming from around #4 cylinder I took off the valve cover and ran the engine and didn't see anything loose and had alot of oil flowing (it went all over) I took a quick video of it but dont know how to post it on here but you can hear it in the video .. any ideas what it could be ? About to replace the engine but at over $1000 I want to be sure it's not a easier fix first