Cooling MacSkier

After installing the rebuilt engine, we experienced very low engine temperatures the first few hours of operation. Cruise to Grafton, and keep your eyes on the temperature gauge:

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The temperature gauge and sensor were properly matched, but te gauge's needle hardly moved off the cold peg. The new 160F automotive thermostat was tested on the kitchen stove and functioned properly.

Here are some photos of the plumbing as we had the hoses connected. (We thought we had them arranged the way they were before the engine was removed for rebuild, but that was not the case. As it turns out, the error was minor, only reversing the flow through the "lower" exhaust manifold chambers.)

Drawing from the PCM manual (with shut-off in pickup hose, one pickup, engine oil cooler and other inaccuracies):

Don't bother clicking above for larger image.

Ken wrote: About those two hull intakes, the CCF explanation of that is that the Chryslers back then had 2 intakes and I think 2 pumps or 2 T'stats also. They had a cooling system that makes yours look simple, it was crazy. Don't know anything about them. The story seems to be that they just made all the boats with 2 intakes whether they were getting a Chrysler or something else.

Anyway, here are my drawings of the "correct" set up. (I should have seen the obvious error -- we (and the PO) had water trying to flow from the bottom rear of the exhaust manifolds TO the front of the rather than TO the thermostat housing. DUH!) 4/11/16 -- We connected everything as per the following revised drawings, and still have cold temperatures. -- Colder than experienced earlier -- except for the top of the exhaust manifolds. They were HOT! (250F) We are currently stumped.

Revised drawing #1.

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Revised drawing #2

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Drawing #3 -- showing interior configuration of thermostat and pressure relief valve housing.

  • The Raw Water Pump (RWP) supplies "lake water" to the engine's cooling system, after being used to cool the transmission fluid.

    The water enters a chamber with three outlets;

    1. Up -- thru a pressure relief valve,
    2. Aft -- into the thermostat chamber, and
    3. starboard to the (Ford) engine's water pump.

    Click above for larger image.
  • The Ford pump pushes water through the engine block, the cylinder heads and the intake manifold. The water exits the engine via a casting (where a car's thermostat would be located) on the intake manifold. The casting has two exit tubes -- feeding the "lower" water passages in each of the starboard and port exhaust manifolds -- via "long" rubber hoses. (WRONG -- The "long" rubber hose RETURNS water from the aft end of the manifold. The "lower" water paths in the manifolds are fed with "short" hoses, INTO the forward manifold caps.)
  • The (now warm) water exits the forward ends of the exhaust manifolds via hoses connected to each side of the thermostat housing. Revised -- the water flows INTO the front of the manifolds and OUT OF the aft ends. Stay tuned.
  • In the thermostat housing, the warm water mixes with cold lake water -- water fed by the RWP through the "pressure relief valve" chamber (not the valve) and into the thermostat chamber.
  • This combination of warm and cold water should (IMO) be warm enough to open the thermostat which should let the mixture pass through the upper housing, exiting through two hoses feeding the two exhaust manifolds, mix with engine exhaust and return to the lake. (But, in practice the temperature is never high enough to open the 'stat, so the engine runs cool -- about 110F.)

Check out these photos of the contraption we call the thermostat housing:

Top of the four-part contraption

Top of the four-part contraption, view #2

Top lifted off
(Red arrows "IN" to 'stat chamber showed DESIRED path,
not the path when photo was made.)

Top & "middle piece" lifted off

Did the boat HAVE a thermostat?
I really can't remember.

The plugs looked pretty good:

_ _ _
Click above for larger images.



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