olds 455 runs hot

Discussion in 'Gas Engines' started by yeoman, Feb 18, 2012.

  1. yeoman
    Joined: Feb 2012
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    yeoman Junior Member

    this is the routing of the circulating pump hoses on my olds 455. It is fresh water cooled through a keel cooler and expansion tank. This photo shows the routing of the hoses between the circulating pump and the exhaust manifold and intake. Is this the "coolest" way to route my hoses to the manifolds? Can someone describe the direction of flow with this arrangement? Does it matter which port on the exhaust manifolds connects to the circulatin pump versus the intake? There is a separate raw water pump which sends water to the logs and out the stern to cool exhaust gases only.

    DSCN0311.jpg
     
  2. kenJ
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    kenJ Senior Member

    We need a better picture of the whole system. Does it cool the other exhaust manifold? How are the rest of the hoses routed? What is the purpose of the valve in the upper left? The basic flow is from the belt driven water pump, into the manifold, out of the manifold, into the top of the engine.
     
  3. gonzo
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    gonzo Senior Member

    What temperature do you call hot? Also, did you use an accurate thermometer?
     
  4. Petros
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    Petros Senior Member

    Tyically in an engine the coolant is circulated from the high pressure (outlet) end of the water pump into the lower part of the block first (around the cylinders), and than it will pump up past the head gasket into the head, and it circulates through the head than routes it way into the intake manifold to warm it (to prevent icing of the carb or EFI system), and than to the front of the intake manifold where it will leave the engine to go into a radiator or cooling system, than sucked back into the low pressure side of the pump.

    What it looks like you are doing there is drawing the warmest part of the coolant from the top of the engine, run it through the exhuast manifold and than draw it into the low pressure side of the water pump. If that is what is happening than this would be the best way to run it, any other direction you will be putting coolant into the engine that was heated by the exhaust manifold.

    Several things to check: make sure you are not getting air pockets trapped in the upper part of the engine. You may have to prime the system by taking off an upper hose and fill the head/intake manifold and than reinstall the head. Make sure the thermostat is in working condition, or just replace it. Buy a good quality one, the cheap ones made in the orient are often junk right out of the box. Make sure there are no pinched hoses, or hoses that collapse when the engine is reved up (this will occur on the low pressure side of the water pump).

    Good luck.
     
  5. gonzo
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    gonzo Senior Member

    Do you have an intake manifold with open rear passages for a closed system or the closed passages for an open system?
     
  6. yeoman
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    yeoman Junior Member

    system

    KenJ - the other side is a duplicate of what you see in the picture. I installed the valve to bleed any air which might get trapped in the intake manifold when adding fluid at the expansion tank. Can't say for sure that it's ever solved any heat problem.

    Gonzo -intake coolant passages are open at each end. She runs hot as in cooking the new paint off the intake at the exhaust crossover. Can't put your hand there for .5 sec once she's run for 4-5 minutes. She's been run half a dozen times for 5-10 minutes since reassemly (new heads).

    Petro - the expansion tank is sourced thru the thermostat and feeds the keel cooler under the hull then returns to what I think you are calling the low pressure side (source) of the circulating pump. Guess i'm wondering if the hoses at the top of the circulating pump are pushing water to the exhaust manifolds or pulling water from them? You and Kenj seem to have opposite ideas on this?

    It is entirely possible that my current "running hot" is the result of a build up of fouling on the keel cooler as we only haul once a year in May. I just don't remember which of the two hoses from the exhaust manifolds went to the circulating pump versus the intake manifold and don't know that it matters.
     
  7. gonzo
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    gonzo Senior Member

    The exhaust crossover is supposed to be hot. It has exhaust gases going through it. What is the head and block temperature?
     
  8. Boston

    Boston Previous Member

    Might consider running some oil solvent through the system briefly. I've noticed that dirty and clogged oil channels sometimes result in hot engines.
     
  9. yeoman
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    yeoman Junior Member

    temperature

    Gonzo - I don't own a temp thermometer. Operating temp at the gauge has always settled just shy of 160 under way. Anything North of that, there was going to be trouble as in boiling over.
     

  10. gonzo
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    gonzo Senior Member

    That is normal operating temperature. GM has gauges set with the redline at 180 which is not yet an overheat.
     
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