There are different kinds of head gasket leakage, and you need to try and distinguish them before jumping to conclusions.

1) Coolant leaking out of the side of the block past the gasket. Not necessarily a problem - leak stop may stop it.

2) Coolant leaking into a cylinder. Difficult starting, poor running until the accumulated water is expelled, white smoke, suspiciously clean plugs and combustion chamber.

3) Combustion gases leaking into the coolant. Bubbles in expansion bottle, smell of exhaust in water, loss of water through bubbling, overheating.

4) Oil leaking out of the block. Unlikely, I believe. There is no pressurised oilway close to the edge of the block, and the drainage passeges are not under pressure.

5) Oil leaking into the coolant. Not possible, I believe, as above.

6) Water leaking into the oil. Very possible. Lots of oil drainage passageways, lots of water passageways. Blobby oil, emulsified.


Check firstly:
Cam seal leakage
Cam cover gasket leaking
Excessive crankcase pressure eg from blocked flame trap or air ventilation hoses.
Oil seaping out of filler cap and running down and then spreading around the line of the gasket edge.