Hi all,
The final verdict from the mechanic and engineering shop is the following. They found that the block was warped (0.14 mm, measured at lowest point) and this caused a leak between top gasket and block. The top gasket showed no evidence of any leaks and the top was also tested.
Unfortunately the mechanic did not flushed the radiator and check if the problem prevails as a 1st step, before taking out the engine and sending it to the engineering shop. This was also a oversight from my side and I now have to pay the school fees for that. Advice I can give to other members is to really take the diagnostic phase very serious and take your time, no matter what the mechanic/workshop is saying. Take your time and seek advice before giving them the go ahead to proceed. One big mistake I have made!
My wife is the primary user of this car and I should have been more diligent in checking the condition of the radiator water myself. Therefore with out proof or good general knowledge, I cannot really say that soap or other foreign liquid entered the system.
I would like to thank all the members for their comments and expert advise, much appreciated. Let's hope the engine is now in a better condition than before and that it will deliver another 100,000 km's problem free.
Best regards
