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  1. #1
    Platinum Member Platinum Member scottw's Avatar
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    How to make this work?

    I have a 1990 454 Magnum Gen IV motor. It had the old six hose thermostat housing which had the balls and fed the risers and the manifolds. This spring I upgraded exhaust to EMI's and added the thermostat housing which is found on the Gen VI motors with the four hoses. Just two that go to manifolds. Has anyone ever experienced water flow problems when adding this newer thermostat housing to a older motor and what did you do to fix the problem?
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  2. #2
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    heat exchanger, or raw water? with new style you are limited to raw water in your new manifolds, anti-freeze in engine only.

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    the old housing had hoses going from the housing to the exhuast manifolds and from the housing to the risers you would need to delete the riser water fittings and plug them and make sure you have the correct riser gaskets. im guessing raw water cooling .

  4. #4
    Registered Platinum Member c_deezy's Avatar
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    Shouldn't be any issue at all.

    The EMI's should have the hose that goes from the manifold to the riser. All you need to do is do the plumbing from the thermostat housing to the bottom of the manifold.


  5. #5
    Charter Member # 55 Charter Member Griff's Avatar
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    Quote Originally Posted by scottw View Post
    I have a 1990 454 Magnum Gen IV motor. It had the old six hose thermostat housing which had the balls and fed the risers and the manifolds. This spring I upgraded exhaust to EMI's and added the thermostat housing which is found on the Gen VI motors with the four hoses. Just two that go to manifolds. Has anyone ever experienced water flow problems when adding this newer thermostat housing to a older motor and what did you do to fix the problem?
    The newer style has an internal bypass system. You just run the hoses from the tsat housing to the bottoms of the manifolds. What kind of problems are you having????

    Quote Originally Posted by dereknkathy View Post
    heat exchanger, or raw water? with new style you are limited to raw water in your new manifolds, anti-freeze in engine only.
    Incorrect.......again.

  6. #6
    Platinum Member Platinum Member scottw's Avatar
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    Quote Originally Posted by Griff View Post
    The newer style has an internal bypass system. You just run the hoses from the tsat housing to the bottoms of the manifolds. What kind of problems are you having????



    Incorrect.......again.
    You would think it would be a direct bolt on but it is not. The flow in the Gen IV motor must be different then the newer Gens . Seems like no water is going into the block. Also the stat gets hit by the cold water coming in from the raw water pump and the stat opens when it get warm and closes right away cause of the cold water. The gauge is all over the place.

  7. #7
    Beak botr VIP Member 88Fount33's Avatar
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    Where did you put the thermostat?

    Did you put it in the intake, or into the new housing?

    Did you line up the blue or white spacer gaps properly into the new housing?

    There are two spacers provided, one for having a machined groove in the intake for the thermostat, the other shorter for a non machined groove intake.

    Just in case you are not aware, the stackup is intake, spacer (proper one) and aligned, then thermostat.

    If you turn the new thermo housing over, you should drop in the thermostat, then push in the spacer, the spacer has a tiny nub that fits a machined notch in the housing so you get it aligned right, then flip the housing over and install onto the intake.

    I purchased these for my rig, and made the mistake of putting the thermostat into the intake, I didn't look at the exploded diagram for stack up until looking on line at Merc parts diagram and then it hit me. I had to look on line because the same "no flow" through the block occurred to me. I had the stack up wrong. Gosh I felt dumb. Once installed properly, it works perfectly.

  8. #8
    Platinum Member Platinum Member scottw's Avatar
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    Quote Originally Posted by 88Fount33 View Post
    Where did you put the thermostat?

    Did you put it in the intake, or into the new housing?

    Did you line up the blue or white spacer gaps properly into the new housing?

    There are two spacers provided, one for having a machined groove in the intake for the thermostat, the other shorter for a non machined groove intake.

    Just in case you are not aware, the stackup is intake, spacer (proper one) and aligned, then thermostat.

    If you turn the new thermo housing over, you should drop in the thermostat, then push in the spacer, the spacer has a tiny nub that fits a machined notch in the housing so you get it aligned right, then flip the housing over and install onto the intake.

    I purchased these for my rig, and made the mistake of putting the thermostat into the intake, I didn't look at the exploded diagram for stack up until looking on line at Merc parts diagram and then it hit me. I had to look on line because the same "no flow" through the block occurred to me. I had the stack up wrong. Gosh I felt dumb. Once installed properly, it works perfectly.
    Everything is set up correctly. Checked stat in water to make sure it was opening at proper temp. The problem I am having is I think most of the water is exiting to the manifolds and not enough is going to the hose that goes to the circulating pump. Shot temps at where the water exits the intake into the thermostat housing and the temp there is around 180* The heads are around 193* which is too hot. There is not enough water going to the circulating pump to push the hot water out of the motor. I need to find a way to restrict the water going to the exhaust.

  9. #9
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    I have done just exactly what you want to do. I have ran it for a couple years with no problems. If you have stock manifolds you need to plug up the riser and only send water to the bottom of the manifolds.the water will go up through the riser and exit. Make sure you have the tstat in correctly with the correct gaskets. I run 160 tstats and no issues !!

  10. #10
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    fixx

    you need 140* high flow thermostats,,97 gallons per minute....if you dont have the thermostats in the correct part of the housing and make sure they are NOT in the intake manifold or else your going to have erratic readings.. it gors from top to bottom,,thermostat housing,then thermostat,thermostat spacer with the small part of the divider facing forward then the gasket..if the divider is not facing forward then you will have lots of water steam problems..

    alot of people dont realise that theirs is a differance in how much water a normal thermostat flows which is like 57 gallons per minute..order a set of thease and have a nice day!

    http://www.hardin-marine.com/p-14347...hermostat.aspx
    Last edited by FIXX; 06-07-2012 at 10:04 PM.


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