Just pondering this one today. When the HGs went on both my Puntos they both did the following:
- A week or two of the engine misfiring a little when idle, getting gradually worse.
- Engine starts to misfire when driving.
- Engine starts to overheat and the more classic signs of white smoke.
So why does the engine over heat as it's still got plenty of coolant in it, the water pump runs regardless and the HG must only be letting a small quantity of coolant into the cylinders? Does the leak reduce pressure in the coolant system? Does the leak cause greater pressure from the cylinders into the coolant system not allowing the coolant to flow through to the radiator. Or is it the other way around, typically something has caused the car to overheat (dead thermostat, trapped air), this causes the head to warp and hence the HG goes? Or a bit of both?
Just curious.
Tim