Hello everyone,

I have a 72 blazer small block 350. I started having over heating issues after the winter months and it setting for a while. I changed the cap, thermostat, had the radiator flow tested (they said that it didn't appear to have any blockages) and now I have removed the water pump. The pump appears in good working order. Propeller looks good and no play in the bearings. So I am at a loss as to what the problem could be. Originally I had the fan on backwards, yes I know rookie mistake, and the thermostat didn't appear to be opening so I changed it. It does not overheat in town when I'm driving 50mph or less but when on the hwy and over 50mph. It overheats within 5-10 minutes. Any ideas??

Thank you in advance,
G

 

You have a fan clutch on it? Didn't happen to remove the shroud if it had one? Flushed the engine out since you had the w/p off? Is the belt that drives the w/p slipping?