Joe, thanks for all the info. I have not put more than a couple of hundred of miles on my rebuilt engine. My 48 Chevy came with a non pressurized radiator. I fill the radiator just to cover the core and not to the top to allow for expansion. I have installed a expansion reservior and even when I'm driving my truck some antifreeze ends up in the expansion reservior instead of on the ground. I've taken several temperature readings with a hand held electronic thermometer. Here's some readings that I have taken recently.
While running, at the Thermostat Housing 210 F
Upper Radiator Hose near Thermostat Housing 171 F
Upper Radiator Hose "Hose Clamp" near top tank 204 F
Upper Tank 204 F
Lower Tank 189 F
Lower Radiator Hose 166 F
Using my Hand held Thermometer and not the mechanical temp gage. Starting with a cool engine 99 F within 10 minutes my engine reached 214 F.
I have good flow through the drain valve located on the driver's side on the lower side of the block. What I can tell you is my engine has the original factory fan so it should have the correct blade angle/pitch, etc. The pulley is the original size, diameter. I agree with you that the engine should have been cleaned of course during the rebuilt but I can't verify that it was.
I like your idea of back flushing the coolant system to see if I get any rust flakes, etc. out of the engine.
I may back flush my engine first and if necessary run some Fleetguard Restore Plus a mild acid based coolant cleaner to see if that helps.
Last edited by HeavyChevy48; 09/06/2026 9:09 PM. Reason: wrong temperature readings
