???Hello all. I am having trouble diagnosing a knocking in my JP3 and have tried various approaches. The knocking is definately related to the crankshaft (one knock per revolution) and gets worse as the engine warms up (leading me to suspect piston to valve/head contact, which inspection reveals was not happening).
The sound is difficult to identify and is a light knocking and not a heavy thudding. I've had injectors tested, replaced the injector pump, reground all valve seats (during a decoke), and fitted new exhaust guides//valves.
Listening to all the U tube footage of JP3s, it seeems that most of the old ones have this noise, though I have personally seen JP3s that run sweet as a nut and do not suffer the same.
I have replaced the bevel gears driving the injection pump and am happy that the noise is not coming from there.
Endplay on the main bearing is about 4 thou and does not seem excessive; big end fore and aft play about 15 thou and equal on all bearings (there's no up and down slack); gudgeon pins/bushes all tight.
I do have worn liners (Listard missing from a 2 inch patch at top ring TDC on one cylinder, with slight pitting to the cast iron) and the piston seems very loose in the bore - could this be piston slap??? Strange how it seems to get worse with heating up.
All comments welcome and any advice on whether it's worth pulling a liner or is it opening a can of worms, ie, difficult and likely to result in problems sealing the liner in a corroded engine? Regards, bertie.
ps, does anyone know of a source of new old stock pistons and rings?