I was out in my pasture yesterday idleing around for probably a hour or more. Allof a sudden I could here my raditor overheating and filling the overflow bottle. My gauge read 160 to 170. I turned off the motor andwaited 5 minutes or so for it to quit overflowing and then restarted and it immeditly started overflowing again. I waited another 10 minutes, jumped in and headed for the garage about a 1/4 mile away. It didn't overflow this time but I'm wondering if there was anything left to overflow? This is my guess. Beings the gauge was only at 160-170, I had an air pocket but why? would the thermastat cause this? Or I blew a head gasket or something that is allowing compression into the water circut which then forced the water out? Soryy so long. oh, the motor is a stock 400 with a th350 tranny.