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Thread: What are normal engine coolant temps? Need help with intermittent overheating

  1. #31
    Fuel Injected! MAC's Avatar
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    More updates:

    1) What is considered the normal range for ECT? No consensus. Probably 190-205 depending on your thermostat rating.


    2) At what point would you stop the truck and wait for it to cool down? No consensus. I have set my personal number at 229 or greater - as long as there was no audible boiling or overflow. If there was boiling or overflow I would immediately stop the truck.

    3) Could this be caused by me having the heater core hoses hooked up backwards? No. It does not matter how the heater core is connected on a 1993 TBI truck. There is not a heater control valve and there is no flow restriction in the heater core. My particular problem was that vortec heads were blocking internal coolant passages that allowed for coolant to bypass around the thermostat. The small amount of bypass flow is needed to prevent local hot spots in the cylinder heads.

  2. #32
    Fuel Injected! MAC's Avatar
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    May 2016
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    Even more updates:

    1) Logging knock counts continuously but no knock retard: I was not logging knock counts continuously. The knock counter is cumulative - like your odometer. Jim and steveo explained this well (see above)

    3) Computer blips: No answer yet.

    4) Block learn cells jumping and causing some drive-ability issues: This can be tuned out. Once I resolve this issue for my setup I will come back and post it here.

    Thanks,

    AC

  3. #33
    Fuel Injected!
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    People call it a bypass but it's not a bypass for the thermostat to let coolant flow past the thermostat into the radiator. It is a path that allows coolant to circulate in the block and heads with the thermostat closed.

    In a typical installation the heater hoses are connected to the intake beside the thermostat and to the port on the side of the water pump. This allows coolant to circulate in the block just fine with the thermostat closed. The water path is from the pump into the block, up into the heads, forward into the front intake coolant crossover, out to the heater core and then back into the pump.

    I don't know the heater configuration on your application though. Is it one hose to the intake and the other hose to the radiator? That configuration should still cause flow in this path - pump to block to heads to intake to heater to radiator to pump.

    In both cases, the heater hose is likely connected to the passenger side of the intake but this just means the coolant flows from the drivers head to the hose passing by the thermostat so it detects the coolant temperature.

    If the heater is configured so the hoses go to the water pump port and the radiator then that would not allow coolant to circulate in the block. I can't see the heater working very well either though since it would be using coolant from the radiator and not right from the engine.

    Your description of the internal block passageway is wrong. The coolant flows down from the head into the block and then into the pump, not the other way around. When the pump pushes the coolant into the block then heads and finally up to the intake, the passage lets some of that coolant flow back to the pump.

    In your particular engine you might have been getting a little air at the thermostat when cold so it wasn't detecting the hot coolant as quickly when the engine was started.
    Last edited by lionelhutz; 06-23-2017 at 07:57 AM.

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