I've been plagued with an annoying overheating problem that I could not figure out. I installed a 1955 235 in our '36 Low Cab and had the radiator rodded out and it flowed perfect. I installed an electric fan and a modified water pump shortened to fit in between the 235 and the rad. I had constant minor overheating, steam and water coming out of the rad overflow tube any time I stopped, even short distances. I thought , well it's a non pressure system this must of happened all the time to the old timers. I continually put water in. I put a S&W water temp guage in to monitor the temprature. The Temp guage would slowly climb to about 180 and sit there while I crusing at 45 to 50 MPH.then slowly climb to the forbiden zone of 200-210, I pulled over to the first available side street and got out to see steam coming out of not only the vent tube but my exhaust stack as well. Typically not a good sign.I did have the presence of mind to feel the rad at the bottom and it was cold...no flow I thought, what the heck. I shut off the ignition and towed the rig home. Fired it up after it cooled off and had coolant coming out of the exhaust, DANG, cracked head at the exhaust port. I was sick. To make a long story short, When I installed the new engine I had put a new thermostat in that was laying around the shop and my mind was still thinking about closed systems. The thermostat that was in it was a 190, I put a 170 in and all is well with no temp climbing and I can see when the 170 opens. That small mistake cost me a new head and a weeks of down time. $ 5.00 part and man did I learn about open system cooling.
