Everyone,

This weekend, which was a hot one in Portland, I was driving the 145 with a relatively stock B20 and ran into some overheating problems. I was running a relatively hot thermostat (192 degrees) but I have had no trouble since doing a reseal on the engine a couple month ago. At that time I put in this brand new thermostat and a new water pump, so I find it hard to believe that those are at fault. Anyway, as I was going up a rather long, steep hill my temperature gauge started going up and when it went past P I slowed down and tried to cool the sucker down. I got over the hill, coasted down and it cooled off but my friend following me flagged me down because coolant hit his windshield and I was puffing white smoke when shifting. We opened the hood to find that the coolant bottle had definitely overflow, pouring coolant everywhere. We topped it off and kept driving, seeing no significant issues beside the puffing white smoke and a temperature needle that seemed to be moving more and more. Once we reached our destination, we pulled out the thermostat for the return trip but this didn't solve my problem. On the return trip, even running without a thermostat at all, the engine would have significant rises in temperature under load (going up hills, etc.) and, if I had not used the heater to help cool the engine, I think it may have overheated once again.

My questions are two fold. First, what are the possible causes of the overheat? I am running a stock, older style radiator with the viscous slip type fan but at high speeds I don't think this is the problem. My friend and I are currently thinking that there is some sort of blockage to blame and are going to try flushing the coolant with a garden hose to try and unblock the system. I was also planning on switching to an early style 140 brass radiator (with the coolant hose coming in at the top center) but I don't think the radiator can be the source of the problem (I have used it previously without issues).

Second, I wanted to ask about the white smoke. This has to mean my head gasket has been damaged, correct? I am planning on replacing it but I want to see what everyone thinks before dropping the money on a new gasket.

Thanks,
Brian