Ok so my car sounds like a tractor on startup untill pressure builds ie warms up,if I place my finger on rocker cover Ican feel chain hitting rocker cover when it's warm this no longer happens!!, So far I have replaced vvt unit with Chinese copy!!,same problem persists even fitted new rocker cover and it has teeth marks in this new one aswell I have taken rocker cover off checked cams ect all look ok,16 rollers between the two cams inlet cam is slightly towards inlet manifold were as exshaust notch is bang on? i have no fault codes only rattles on cold start I have taken sump off I'm going too replace oil pump, oil is golden no sludge or in pick up pipe the only thing I can think is worn oil pump I have pump off ,checking pump they say look for scores in piston?? i have also noticed vvt piston has scores in it don't really want too take the vvt out again but I am thinking maybe ablocked oil passage in head leading too vvt unit as the old vvt had its mesh missing,I didn't check the oil passage my bad! I have checked oil pumps oil passage and it seems all clear any ideas as I'm in two minds weather too take out intake cam and remove vvt?or should I just. Try oil pump first??? and the big question gsf/ Trojan oil pump 50? Or tps oil pump 110? Any diffrences ie do they both idle at same pressure??????