Unexplained coolant loss

[martyw]

Hi, I have a 2003 Rover 75, 1.8 turbo with 70000 recorded miles. I bought the car with an hgf / water lose problem and have recently replaced the HG, water pump, belt and tensioner and oil pump. The engine has run for 1 and a half hours in total and only travelled 6 miles and that was to get the MOT done which it passed with flying colours. The engine sounded perfect and in the garage they said the engine would pass the water glass test it was running so smoothly. I checked the water before I left and it was on the maximum line however on starting the engine after the MOT it was firing on three cylinders with smoke coming from the exhaust. This problem cleared although there was still smoke but I was able to recover the car back home without over heating. The engine management light was lit and on checking the 2 codes it was engine misfire and engine misfire due to fuel starvation. The cooling system took 3 quarters of a litre of water to bring the level back to the maximum line.
I have checked the oil which shows signs of water mixed in with it but there are no signs of oil in the cooling system. The tops of the pistons are dry when looking though the plug holes and the plugs them selves showed no signs of water. I am not entirely convinced that the problem is due to a hgf again because of the amount of water lose in such a short period of time, and the history of the car shows that there was an unexplained water lose before I bought it. I locked the engine flywheel before removing the head so there was no movement of the liners while I was working on the engine, and I also checked the liners for possible cracks and as far as I could see there were none.
My question is has anybody had the same problem and found it was caused by something other than the head gasket. I have a feeling that it could be that the turbo was damaged before I commenced work and perhaps the seals have perished allowing water to pass from the water cooling in the turbo to the oil passages but I am unsure. I also checked to see if there was any signs of coolant lose around the engine but found none at all.
Any suggestions would be most appreciated as I am at a loss to what it could be.
Regards and many thanks Marty

edit: Tuesday 21 July, I have now drained the coolant and oil and found no trace of cross contamination in either.