exhaust manifold hoses

Discussion in 'Powerboats' started by yeoman, Feb 5, 2012.

  1. yeoman
    Joined: Feb 2012
    Posts: 9
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Maryland

    yeoman Junior Member

    I have a fresh water cooled Olds 455 in my boat. (cooled by a keel cooler). Question: the exhaust manifolds have two ports at the forward end one of which receives water from the water pump and the other exits the exhaust manifold to the intake manifold. Does it matter which port is used for each function? I'm guessing not but can't remember which was which prior to removal to replace the heads. Thanks.
     
  2. tunnels

    tunnels Previous Member

    logics would say in the front out the back !! front is usually higher and back is normally lower! not that that makes any differance . :D
     
  3. stringy
    Joined: Mar 2010
    Posts: 16
    Likes: 2, Points: 0, Legacy Rep: 21
    Location: Australia, NSW, Muswellbrook

    stringy Junior Member

    Water needs to go in at the lowest point and exit at the highest, these points should be as far away from each other as possible. This will keep the manifold full of water and flow the water through from one end to the other.
     
  4. gonzo
    Joined: Aug 2002
    Posts: 13,564
    Likes: 375, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    The water usually flows to the block first and the exits through the exhaust manifold.
     
  5. whitepointer23

    whitepointer23 Previous Member

    some olds engines in cars ran the coolant through the inlet manifold and heads then block. opposite way round to normal. that came up in a search of chev v8's i read the other night.
     
  6. tunnels

    tunnels Previous Member

    Yeah the coolant was to warm the intake manifold not to cool !!if you have a look in the bottom of the manifold it had fins cast in to help the atomizing the droplets of fuel and so making them run better and a little more econimical . ""OLD TECHNOLOGY "":D

    Thats why the old side valve 4s and 6s had the intake manifolds bolted to and sitting directly on the exhaust manifold . warmed almost instantly in cold weather and ran better . Thats why water as used to warm the V8 motors also the automatic choke had a water feed on some models . Tempramental things they were !!
     
  7. gonzo
    Joined: Aug 2002
    Posts: 13,564
    Likes: 375, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    The water always goes into the intake manifold first. The OP is saying the water goes into the exhaust manifold.
     
  8. Frosty

    Frosty Previous Member

    If it has a turbo it goes into the intercooler first.

    It needs to warm up a bit first or you will get thermal shock.
     
  9. gonzo
    Joined: Aug 2002
    Posts: 13,564
    Likes: 375, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Sure, and also goes through the transmission and power steering coolers too if installed.
     
  10. whitepointer23

    whitepointer23 Previous Member

    i know about the warming the intake bit but what i read the other night was that some olds v8' ran the coolant from the water pump through the inlet and down through the heads to the block instead of through the block and up through the heads like a normal engine thats why i thought it might relate to the coolant flow the op out lined. i don't know how long ago that system was dropped though.
     
  11. gonzo
    Joined: Aug 2002
    Posts: 13,564
    Likes: 375, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Marine V8 American engines get the water in through the front of the intake manifold. The thermostat housing is there. Surplus water bypasses directly to the exhaust manifold. Cars have closed systems and the intake manifold is different. Marine manifolds don't have a lower crossover, even though the look the same from the outside.
     
  12. whitepointer23

    whitepointer23 Previous Member

    no worrys, my 307 chev is raw water cooled, it feeds the water through the exh manifolds to the block then out the thermo housing to the risers.
     
  13. Frosty

    Frosty Previous Member

    The water pump is on the front of the block,-- if you feed it with water then it feeds the block. The block is its only way out.

    The engine also takes advantage of thermal current,--the model T had no pump just a high rise radiator.

    The V8 outlets hot water to the radiator from the thermostat at the front of into the radiator where the water is cooled and then falls by convection to the bottom and then back into the engine..

    Hot water rises in the engine and makes it way to the radiator top,--why would you try to push it the other way round
     
  14. gonzo
    Joined: Aug 2002
    Posts: 13,564
    Likes: 375, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    An impeller raw water pump plus a circulating pump have so much flow and pressure that the temperature differencial is irrelevant.
     

  15. tunnels

    tunnels Previous Member

    wooow best to discribe the cooling system first !!
    The std pump on the motor is recirculating fresh water through a heat exchanger!! the raw water (salt water )is cooling the circulating water via the heat exchanger !!,
    The raw water (salt water ) then goes through the exhaust manifolds and out the exhaust pipes !!
    Right ???? :confused:
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.