Hi. Mate of mine has a 60k mile 200 tdi 90. He parked it and nipped to the shop, when he got back the oil light stayed on when he started the engine. Towed it to garage put a pressure gauge on it. No pressure. Put a new oil pump on it. Light went out at tick over, came on and stayed on when he revved it. He took the engine out, stripped it almost completely. (left the cam and pistons in it). No visible damage or bits missing, no burst castings or missing oilers. No magically disappearing main bearings.
Meantime, I took his old pump and stripped it. Apart from one thing it looked like a good 60k pump. When I polished the relief valve plunger there was one ding in it that was too severe to polish out. Plunger was not stuck open on stripping, no feelable grit in the oil. Plunger smooth and loose in housing.
Mate carefully and cleanly rebuild engine and without cam belt on (with pistons clear) he drove the camsaft round with his pistol drill.
50 odd psi on a gauge, just like a propper one. Finished engine, installed, ran it, checked it, everything great.Half way to work this morning the oil light came on and stayed on.
Is this a surprising collection of coincidences, or is there some known problem thats been missed?
Thanks Tim