2018 Haval H2 Pricing and Specs

A faulty transmission oil cooler, which uses the engine’s radiator and coolant, could definitely mix oil with coolant. And while that could lead to overheating as the coolant fills the transmission, you’d also probably notice the transmission dying a not-so-slow death due to coolant polluting the lubricating transmission fluid. But it’s less likely to pressurise the cooling system to the point where the oil-and-water mix exits through the expansion bottle.

Much more likely is that the coolant system is being pressurised by the combustion of the engine. If the cylinder head has been checked and the gasket replaced (assuming it was all done properly) then the pressurisation is probably coming from somewhere deeper in the engine’s crankcase. You need to check the cylinder bore for splits or cracks and take it from there.

Before doing anything, though, check the date of first registration of your car. If it was first registered after October 1, 2018, then it is covered by Haval’s seven-year/unlimited-kilometre warranty. If it was prior to that, then it would have come with a five-year/100,000km warranty which, technically, will have expired. Even so, it would be worth contacting Haval’s local customer service division to see if the company is open to helping with repair costs given the vehicle is only just out of warranty. This presumes, of course, that the vehicle has been serviced correctly and at the appropriate intervals.