why is my head knocking....please help

[custom e30]

so i have a bad knock and there are several shops in the area who specialize in bmw's, everyone seems to think its something to do with the head, you right in the middle of the head so i pulled off the valve cover and pulled the intake side rocker arm to the side of cylinder #4 so that the car would have a miss, when i started the car and drove it, the knock was gone, but that can mean a couple different things, so i put everthing back together and the knock is back,

so here i am 1 week later and i came across 2 loose nuts on the bottom of the header manifold on cylinders #1 and #2, but every other nut is perfectly tightened to specs. but the 2 nuts have been loose for probably 5 months,

my question is, can the loose nuts on the header create this knock i have?

[custom e30]

Video of knocking engine

http://www.youtube.com/watch?v=_3m_70jkINA

[jlevie]

That sounds to me like it might be a rod bearing.

[custom e30]

then wouldn't it do it all the time, cuz i did have a bad rod bearing at 1 point and it was totally different sound and acting?

[jlevie]

Cold oil is thicker and may hide the wear until the engine warms up. Also a slightly worn bearing may only make noise at certain loading conditions. Take the car to a shop and get a pro's opinion as to the cause of the noise.

[KillaCams]

Does it knock when you rev it in neutral? Can you feel any vibration in the clutch pedal? My m20 had a bad rod bearing in December and it was knocking wayyy harder than that and the knocking could be felt in the pedal. From what it sounds like maybe something is loose in the head, are the valves adjusted correctly? Everything all torqued down correctly? Maybe a rocker arm on it's way out? What kind of oil you running?

[custom e30]

mobile 20w50 full synthetic, i can feel it in the brake only when the knock peaks at its hardest, valves could use a adjusting but it runs really smooth,rockers seem fine?

[xwill112x]

rod knock or piston slap/play

[Predzy743]

Dude.. what kind of exhaust do you have? That sounds tits! Sorry to jump in like that. I really hope you get that fixed. Sounds like bad piston slap to me. My quad had that and it was just real bad rings.

[Kershaw]

amazing cluster.