Decreasing in Coolant Level Grand Voyager 2.8
 

Hello, I need som help for my 2005 Grand Voyager 2.8 CRD.

I took a ride about 300 miles, then my car started to emit white smoke and at the same time I realized that the coolant level decreased. Before the ride, there was little white smoke, and I had a AC heating problem (AC was not heating)

Than I used head gasket block seal and it has worked, the white smoke is stopped. And also I have gained more power.

However, decreasing of coolant level is still ongoing. AC heating problem is still ongoing. And sometimes, overheating problem occurs when I use my car in an uphill road.

My mechanic says that I have a thermostat problem, I guess as well. But I could not find the reason why coolant level is decreasing.