Buggeration. 300 miles this weekend and 5 litres of coolant No visible sign of loss, but the oil is very watery. No emulsion (yet) but I expect it will as things cool.
The question is, what has failed and how can I prove it? There is a slim chance the oil/water heat exchanger is leaking, but I really can't see how that would allow coolant into the oil but not the other way round. So that to me suggests coolant leaking into an area of oil at low pressure, such as a return oilway in the HG.
I can bypass the heat exchanger coolant pipes, to see if the loss stops, however I can't really see it being that. But the question remains that if I take the head off and no gasket failure is obvious, can I prove the head is OK? Would getting it pressure tested only check the combustion chambers? I'm confident there's no leakage in this respect - no pressurisation when I undo the cap.
Around 8 years ago I was losing maybe a litre every 1000 miles, and I put in K Seal as a short term 'fix' as I was short on cash...wondering if it's the same failure again. No visible loss then either! Back then I'd read that the heads are prone to cracking, so feared the worst.