2002 Mazda MPV Blown Head Gasket & other issues?
 

My 2002 MPV was bought in Feb. 2008 started having heating/coolant problems that summer. First we had a thermostat replaced then overheating problems continued so we found out the radiator needed replaced & did that. Now coolant leaks by the gallon it seems after driving the van for a while. I should also say that we had rear coolant leaking issues so we had the rear lines sealed off we felt at the time that the lines & rear system itself went bad because of coroding (sp?) due to horrible weather we had & snow salt reaching the lines etc. So now we have the van still leaking out coolant can't say for sure where from at this point but it comes out green even if the van was just filled up completely with water it still comes out green. I'm about to go check the van again but I can't recall ever seeing whie smoke come out of the exhaust I thought that was a major indicator. Anything else I should be looking for??

I was told by the mechanic who put in the new raditor that the head gasket is now blown. Im not one to just believe soemthing someone tells me without a good explaination & some research of my own. Now if the head is blown the plan is to junk the van but before I do so I want to be sure it is blown. I aslo wanted to try out the ThermaGasket or Steel Seal I've heard so much about doing my internet research. Has anyone used these liquid methods to fix a blown head? Or are they just rip offs?

Thanks for any & all help!