thanks ill have a look
More than likely you have a worn rod bearing on No.4 cylinder, removing the HT lead stops the combustion process and relieves most of the load off of that bearing, hence the reason why the knock goes away when that cylinder isn't firing. When one rod bearing is worn the chances are the remaining rod bearings and most likely the main crank bearings are not far behind. Depending on the mileage the engine has covered this will be a result of a poor service history or low oil pressure. If it's the latter then new bearing shells won't cure the problem, the oil pressure issue needs to be addressed first.I have a knock comming from bottom end, not on idle it's more pronounced when feathering the throttle. If I unplugg the ht lead on piston 4 I believe (next to cam belt) it stops!?
good info, do you think this caused the engine failure?