I have recently picked up a 2003 318i SE with a known fault. The car seems to loose a pint of water only on any journey between 20 miles to 100 miles but definately no signs of any puddles / leaks. The car doesn't overheat and after it reaches 20 miles plus the coolant light appears on the dash and after about 80 miles or so the oil light flashes on intermittently. When I put my foot down at about 65mph the engine stutters then all of a sudden will react and pull normally. When I start the car from cold it doesn't idle very well and there is no heat coming from the heater although it does blow well.
I have had two mechanics look at it and it has been pressure tested twice to no avail although one did say that the pressure seemed quite high??? I have checked the interior for leaks (carpets etc) but everything is normal.
I checked the seller's previous ebay purchases and found that he had purchased a bottle of K Seal and so I presume he has tried that, so has anyone got any ideas or experienced a similar problem because I expect a head gasket problem but would rather not open it up unless I really have to if someone could pin point in the right direction.