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Thread: Loosing antifreeze

  1. #1

    Loosing antifreeze

    I'm gonna throw this out there before I pull the motor. I've had this car since oct. and it loose's about half a radiator of antifreeze I've topped it off 3 times to date. The car does not run hot or leak antifreeze and does not smoke, any possible suggestions? Thanks in advance for any input.

  2. #2
    Senior Member RACING JUNKIE
    Join Date
    Sep 2007
    orland pk il
    what is it ??

  3. #3
    small block 406.

  4. #4
    Senior Member RACING JUNKIE
    Join Date
    Jan 2006
    400 blocks are notorious for cracking between the head bolt holes and the cylinder. The holes are not blind and go into the water jacket. This could be your problem it's sucking water into the cylinder but not enough to make it smoke and as long as you keep the water level up it won't run hot.



  5. #5
    Senior Member EXPERT BUILDER
    Join Date
    Nov 2009
    Survey Says... A low pressure, worn out, or broken radiator cap!

    The pump flow is probably blowing out coolant thru the overflow tube at higher rpms. (that is if you don't have a catch can or reservoir which then would be obviously wrong answer because it is catching the blowout and filling up the can).

    We see this a lot in dirt circle track engines running high rpms for 15 minutes or more per race, and not using a restrictor plate or thermostat to slow down the flow pressures. It blows the water right out the cap and overflow tube, so we use a 29# cap, and slow the pump down with reduction pulleys.

    Before you tear down or pull engine, try a brand new top name brand radiator cap, in at least 24# or higher, which will also increase boil over threshold.

    Also, get someone to help you do a proper coolant system pressure leakdown test... just to be sure.

    If you don't have an overheating problem, (GM block 406 overbores are notorious for overheating) you could also try reduction pulleys to slow the water pump down. Also use a restrictor plate or thermostat to regulate the flow travel pressures.

    I'm not hatin... I'm just sayin...

  6. #6
    Senior Member RACING JUNKIE
    Join Date
    May 2006
    X2 ---> what zip said.
    ***IN GOD WE TRUST***

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