Overheat/Misfire/HGF?

Rover 75 1.8T petrol auto. '05 plate 40K



Bought this car 9 months ago. It had problems immediately. Rough engine, no power, smoke from exhaust. Was initially diagnosed as a misfire, so had full set of plugs & leads replaced. 1 week later, problem recurred but worse; diagnosed as HGF. Dealer replaced under warranty, with an improved (aluminium?) Head Gasket.



All was well, until last week when the same symptoms came back. Engine has a lot of vibration, blue/white smoke from exhaust, engine warning light on. Limped to local garage, only error code is 'misfire': same as last time. Only other issue seems to be ecu reporting the coolant temperature as hot when it seemed to be cool. No obvious 'mayonaise' in coolant or oil. Mechanic seems to think this is another HGF, due to some uderlying cooling issue. The paperwork I got with the car suggests that the water pump had been replaced not long before I acquired it, which leads me to wonder if there had been unresolved issues with the cooling system which led to the car being disposed of.



With code reset, seemed to be Ok for a day then problems return. Bought a cheap diagnostic tool, which again seems to suggest that coolant temp is either v hot or not being reported properly (or just a bug with the cheap tool).



I am a bit stuck as to what to do next. No point replacing HG if it fails after 6 months due to possible overheating issues. Really need a Rover expert in the Derby area to look at it, if anyone can suggest one. Or a laymans guide as to how to diagnose the underlying issues.



Any advice will be welcome, thanks!

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