hi all i have a query about my 95 300 tdi discovery hope someone can help me get to the bottom of my problem, travelling up the m54 it overheated and cut out,i got to destination (luckily 1/2 mile of the 54) and i took out the thermostat and topped up with water then i found out that the header tank had split from the pressure,i fibreglassed it up and filled up again and it started with no problems and ran perfect,until i got another 50 mile (outside my front door...they do say a landrover will always get you home!!) and it started to sound rattly, next day i took another look at but it wasnt as simple this time it started but with a knocking sound through the intercooler pipe which i could actually feel through the pipe,anyway changed headgasket and all valves,all pushrods looked fine,put back together proper torque settings and sequence (not the 1st one ive done) but it still sounds the same a knocking sound through the intercooler pipe,ive listened with a bar all over the engine but cannot hear any knocking within the engine itself,when its on a high rev it sounds like its pinking like the timings out but i didnt have to disturb the timing belt ??????????? any ideas at all anyone as its very frustrating,all the rocker arms are fine no broken or chipped ones all the bores and pistons seem fine and lying underneath it when running it sounds normal its coming through the inlet manifold and travelling down the intercooler hose please help me to eliminate this horrible knocking sound,many thanks in advance........keith