OVERHEATING SMALL BLOCK

  • JUST CURIOUS I HAVE A SMALL BLOCK FORD AND HAVE CHANGED HEADS , GASKETS, DECKED BLOCK ,PRESSURE CHECKED HEADS AND SWITCHED HEADS . IT BOILS OVER AND I CAN SEE WHAT I THINK IS EXHAUST GAS BUBBLES GOING TO OVER FLOW TANK, PLUS IT IS PUSHING THIS PAST A 24-26 LB RADIATOR CAP. ANY ONE HAVE IDEAS WERE TO LOOK FOR A CRACK IN BLOCK AS WITH I THINK IT HAS TO BE IN BLOCK

  • Kenyon, First check to make sure that your head gaskets are installed correctly. If they are installed correctly you will see a small squared off tab of the head gasket sticking out of the front outer corner part of the head between the lower front bolt and the front of the head. If you do not see this tab, the gaskets are on backwards. If they are the coolant does not flow properly through the heads or the block. This problem is not all that uncommon.


    -Fred-

    65 Koupe early San Jose Phoenician Yellow 4 speed
    66 GT Koupe Dearborn Blue 4 speed
    66 KGT San Jose fastback pony interior Silver Frost 4 speed
    64 Falcon sedan delivery 289 4 speed
    65 Ranchero 289 4 speed
    66 Corvette roadster 427/425 4 speed

  • what is the over bore, if any ? 0.030 over is all you can go and not run into overheating. some can go 0.040 over without issues, others can't.


    Also, don't attribute the bubbles in the overflow to exhaust unless you have a "exhaust sniffer" Any radiator shop can check that for you for nominal fee. There will always be some air in your cooling system, and that is likely what you are seeing. I always have some bubbles appear in the overflow once a hot engine is shut off.


    Z. Ray

  • <BLOCKQUOTE id=quote><font size=1 face="Verdana" id=quote>quote:<hr height=1 noshade id=quote>

    JUST CURIOUS I HAVE A SMALL BLOCK FORD AND HAVE CHANGED HEADS , GASKETS, DECKED BLOCK ,PRESSURE CHECKED HEADS AND SWITCHED HEADS . IT BOILS OVER AND I CAN SEE WHAT I THINK IS EXHAUST GAS BUBBLES GOING TO OVER FLOW TANK, PLUS IT IS PUSHING THIS PAST A 24-26 LB RADIATOR CAP. ANY ONE HAVE IDEAS WERE TO LOOK FOR A CRACK IN BLOCK AS WITH I THINK IT HAS TO BE IN BLOCK

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    Could your engine be running lean? I bought a car with a hot running 289 in 2003. It would boil over in less than a mile of driving after being not used for more that 16 hours. I started with all the usual checks of tune up specifications and thermostat but found nothing until I pulled the first spark plug. I pulled several others and all showed signs of running very lean. I rebuilt the Holley carburetor that was on it and it stopped over heating.


    Dan

  • I WILL CHECK HEAD GASKETS , OVERBORE IS .030 , AND I CHASSIS DYNO IT AND RAN AIR METER AND RIGHT IN AND WHEN I SAY BOIL OVER I MEAN GO DRIVE AND IN ABOUT 10-15 MINUTES POP HOOD AND OVER FLOW IS FULL AND IT IS A ROLLING BOIL LET IT SIT AND COOL AND THE START UP AND IT SUCKS IT RIGHT BACK IN THANK YOU ALL FOR SUGGESTIONS

  • I run a 13 lbs rad cap Autolite repo. The higher the rad cap preasure like a 22 lbs the higher the Boiling /overflow problems. The risk of heating up your top tank is asking for failure to the sweated on top tank with the heat and excess preasure ie 22lbs cap.

  • Did you check the radiator to see if its the correct 1 or since you wet through all the trobles to rebuild the engine did you have the rad cleaned and rodded out?

    I had a similar problem on a Shelby but radiator was plugged with stop leak.

    You also might want to chack your heater core also.

  • Hi, have you checked your radiator hoses. If they are soft when the motor heats up the hoses can suck in under revs and block the coolant flow. Once you idle the pressure on the hoses isn't so great and they resume their shape and flow again but with a raised temperature.

    Hope you solve it.

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