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  1. #1
    cheatin' piston popper addicted's Avatar
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    open loop with a thermostat. . . Let's discuss

    I wanted to post this up to promote ideas. On my ski, I want to keep the stock thermostat and water pump. I think I have figured out how to do it, but I wanted to see if anyone has tried it, or if there is an inherent flaw that I am missing. It works beautifully in my head

    The easy part- rxp open loop side.

    -rxp restrictor washer ID is 8mm.
    -yammi bilge fitting on the transom plate is 8mm.
    -Hook up the open loop side to a dual cooling line that is run through the bilge fitting and call it done.


    The harder part- closed loop side.

    -install a T and hook up the coolant bottle, coolant bottle nipple and ride plate return nipple(lower right)
    -run hose from tstat(straight out) to the yammi transom plate dump on the right side of the tunnel.
    -drill 2 holes in the coolant bottle up top and install 2 of the same size barbed fittings.
    -run a line from the stock yammi fitting on transom plate to one of these new barbs.
    -install a hose on the other new barb that is the same size as the one from the pump, and run it to a pisser.


    The theory:
    water will be allowed to enter and exit the coolant bottle at the same rate. When the engine is started, only the water in the system will circulate through the motor until it is warmed up. Whatever is pumped in by the jet will be shot overboard at the same rate. When the tstat opens, the bottle and system drain, allowing fresh, cold water that is constantly refilling the coolant bottle to take it's place. if the incoming water is too cold, the tstat closes, and the process repeats.

    Of course there are things like flush fittings and strainers that are not posted, but they are very easy to tie into the system. Also, it would be pretty easy to add some antifreeze or saltaway to the system after riding to minimize corrosion on the water pump and everywhere else.

    I think having a thermostat on a fuel injected engine is crucial for proper operation. Especially since I'm up here in NJ and it's not that warm. I also don't feel like dropping $250 on the block off plate


    So, what do you think? What did I miss?
    Last edited by addicted; 01-09-2008 at 11:24 AM. Reason: sp


  2. #2
    Moderator The Bandit's Avatar
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    I dont know what you may have missed, but in theory it seems like a great idea.

  3. #3
    Duke's Avatar
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    I like the way you think.

    I'll let you know in a few months if it works or not.

  4. #4
    Hydrotoys's Avatar
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    The easy part- rxp open loop side.

    -rxp restrictor washer ID is 8mm.
    -yammi bilge fitting on the transom plate is 8mm.
    -Hook up the open loop side to a dual cooling line that is run through the bilge fitting and call it done.
    In theory... In reality, you may end up around 80psi. Better check it with a gauge.

  5. #5
    Hydrotoys's Avatar
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    As for the converted closed loop, I do NOT want to detract from your idea gathering, but I will add this...

    Dan's open loop works. It works well. It works in all conditions. It works to 160deg like a charm. With reverse cooling it works with more timing, and keeps the oil cooler warm, not cool. Don't discount it, just because a few folks on here are too hard headed to use it. Re-inventing the wheel isn't all that fun sometimes.

    Back to the subject,
    what about using the full cooling system, with some type of pressure bypass between the inlet on the pump, and a seperate dump. So Inlet to system, outlet from system, bypass with a pressure regulator on inlet, and a dump

  6. #6
    ISLAND RACING seadoo951's Avatar
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    What exactly is a tsat and how does it work?

  7. #7
    cheatin' piston popper addicted's Avatar
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    Quote Originally Posted by Hydrotoys View Post
    In theory... In reality, you may end up around 80psi. Better check it with a gauge.
    I take you tried this? Figures nothing is that easy Interesting coincidence though. A guage on the system is a must, regardless.

    Quote Originally Posted by Hydrotoys View Post
    As for the converted closed loop, I do NOT want to detract from your idea gathering, but I will add this...

    Dan's open loop works. It works well. It works in all conditions. It works to 160deg like a charm. With reverse cooling it works with more timing, and keeps the oil cooler warm, not cool. Don't discount it, just because a few folks on here are too hard headed to use it. Re-inventing the wheel isn't all that fun sometimes.

    Back to the subject,
    what about using the full cooling system, with some type of pressure bypass between the inlet on the pump, and a seperate dump. So Inlet to system, outlet from system, bypass with a pressure regulator on inlet, and a dump
    I'm not knocking the open loop system at all. Just trying to build a better mouse trap. My ski is staying stock, at least for the immediate future, so I won't have the added heat that you guys build with the modded motors.

    If I am following you correctly, you are basically adding a pressure regulator and bypass in the inlet from the pump to what I proposed? I figure that having the in and out on the coolant bottle would function the same, or at least the fitting on the pisser could be adjusted to allow more or less water out. That would regulate the pressure without adding complexity. . . in theory, of course.

  8. #8
    cheatin' piston popper addicted's Avatar
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    Quote Originally Posted by seadoo951 View Post
    What exactly is a tsat and how does it work?
    tstat= thermostat spelled the lazy way just a heat actuated water valve.

  9. #9
    ISLAND RACING seadoo951's Avatar
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    ooooooooh. Gotcha. I was thinking it was some kind of solenoid or something.
    Quote Originally Posted by addicted View Post
    tstat= thermostat spelled the lazy way just a heat actuated water valve.

  10. #10
    cheatin' piston popper addicted's Avatar
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    Just an update on this.

    On my conversion I am having pretty good luck with this. The IC and exhaust side is working well and the pressure looks pretty good.

    On the engine side, I had an issue with too much pressure, bit it looks like i fixed that by adding a 2nd pisser to the coolant tank.

    I thought that when the thermostat was closed, there was no bypass, but there is. So having the bottle full as a reserve so that when the thermostat opens and it can dump is not necessary. it really just needs a steady trickle, as far as I can tell.

    SO, I think 'm going to make a small manifold and ditch the coolant tank.

    Again, any input is welcomed.

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