Hello Advance Design Chevy Truck Fans. I have a 48 Chevy 1/2 ton 216 C.I straight six which is numbers matching and appears to be the original stovebolt enginge. I need help as my engine has an over heating problem that I have been troubleshooting and I have not found and/or fixed the problem. Let me tell you what I know.
Within 30 minutes of idling she pegs out the temp gauge "212 'F" It takes longer if I'm driving, but she creeps up to +200'F and then when you shut the engine off of course the fan stops spinning and the temp gauge pegs out! I had my engine rebuilt several years ago and we installed a new aftermarket water pump. Still I just installed another rebuilt water pump in an attempt to fix the overheating problem..Doing research I was instructed to make sure that the back of the water pump impeller and the water pump backing plate it is critical that the gap in no more that 0.040". They claim that several aftermarket water pumps have too large of a gap and they don't push coolant like they should. I ensured that I had a gap no larger than 0.040" and the coolant appears to be strongly swirling when watching it with the radiator cap off as soon as the thermostat opens. It has the original style OEM radiator and it appears to be working as advertised. I've researched and played with the timing. The vacuum advance on the distributor seems to be working fine while accelerating the engine. All the plugs have a nice tan color so it doesn't appear to be a fuel mixture problem. I replaced the thermostat with a 160'F thermostat. My radiator cap is the non pressurized type. I've watched the temperatures with a infared thermometer. The temp gauge is not wrong as I have measured the temperature where the capillary tube screws into the cylinder head. I've used the infared thermometer to check the top and tanks of the radiator and radiator tubes, There's no bubbling of the coolant. There appears to be no oil in the coolant and/or coolant in the engine oil. There's no white smoke coming from the tail pipe and no sweet smell of antifreeze. I have also installed a 6 volt pushing electric fan in front of the radiator to help out the situation but it only minimally helps out. I've thought about fabricated a radiator shroud, but this may not even be worth doing as far as I know these old truck didn't come with a radiator shroud and doing so maybe putting a band aid on the situation. I appreciate any advice.
