Hi looking for advise, I sold the Corsa SXI 1.2 1.6v person came back with it over heating, white smoke, running badly and over pressured coolant.

I took the head off, got it skimmed, new head set set and rebuilt. All seemed well it runs very smooth person was happy, 10 days later get a call stating that the temperature light had came back on and the it had lost its coolant again. Now it's back there is white smoke, and the water pump is shot. They took it to a garage that said the head gasket had failed as the dipped the coolant and the was exhaust gas in there. There are no other symptoms of the head gasket it not running badly, not over heating while the there is coolant in it and it's not over pressuring the coolant.

The only other place the exhaust gas can mix with the coolant is the egr valve but will this give the white smoke?

Many Thanks

Matt