Forgive me ... but dual cooling off the head from a single inlet ...
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  1. #1
    PWCToday Newbie
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    Forgive me ... but dual cooling off the head from a single inlet ...

    Rebuilding a beast and yesterdayís first short test loop the pisser wasnít pissing enough to make me comfortable ...

    As youíll see, itís a PP with Westcoast pipe and manifold. Single cooling line it.

    So, this was how he routed it, what do I have messed up? (Finger just to hold line out of the way for pic lol) Cooling line comes in and splits to the manifold (impossible to see in pic). Front of head goes to front of pipe. Back of pipe goes to stinger and T to pisser (not connected in pic) ... NOW, the line off the back of the head WAS where the previous owner had the hose connection ... should that go straight to a second pisser?




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  2. #2
    PWCToday.com Is My Home Away From Home fastgtfairlane's Avatar
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    Re: Forgive me ... but dual cooling off the head from a single inlet ...

    If you only have one line going in, you should have one line coming out. That rear fitting on the head should be capped off. Everything else looks fine. If you have 2 lines feeding the exhaust manifold then run that rear line on the head to a pisser.
    96 superjet- rockered, -4, wide tray, adjustable footholds, kv148 mag setback pump, skat 7/14 impeller, rrp adjustable pole, blowsion ovp steering, 62t/62t, ada head, zeel A02T cdi, dual 44s, boysen power reeds, TNT SS chamber

    93-x2, newmiller ported SP750, milled head, R&D single 46 intake, sbn46, fpp blaster chamber pipe, hooker 9/15, umi, rhaas squirrel cage, dakine foot straps

  3. #3
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    Re: Forgive me ... but dual cooling off the head from a single inlet ...

    That rear line off the head was capped with the hose inlet for flushing.

    When I briefly ran it like that there was very little water coming from the pisser - not a solid stream; basically tricked out - so I came in before overheating. When I checked the lines they were pretty warm (makes sense) ... but so was the inlet line? Why would that line get hot? My thinking was the capped head was causing a backflush


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  4. #4
    Top Dog JC-SuperJet's Avatar
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    Re: Forgive me ... but dual cooling off the head from a single inlet ...

    Those pretty Green Hoses don't handle Heat very well and can collapse/flatten and limit flow.

    The Inlet Line gets warm because it is in contact with the Exhaust Manifold which gets very Hot.

    I've had a Pretty Hose collapse on itself right before the Exhaust Manifold Inlet Fitting, block flow and overheat my Engine. Fortunately, the Thermosensor prevented any damage.

    Heater Hose is better for Cooling Lines.

  5. #5
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    Re: Forgive me ... but dual cooling off the head from a single inlet ...

    Quote Originally Posted by JC-SuperJet View Post
    Those pretty Green Hoses don't handle Heat very well and can collapse/flatten and limit flow.

    The Inlet Line gets warm because it is in contact with the Exhaust Manifold which gets very Hot.

    I've had a Pretty Hose collapse on itself right before the Exhaust Manifold Inlet Fitting, block flow and overheat my Engine. Fortunately, the Thermosensor prevented any damage.

    Heater Hose is better for Cooling Lines.
    Fair enough about the contact and heat - makes sense to me.

    Most of these lines are brand new - and I ran the same on my stock 550 for a decade without issue. Iíll keep an eye on them for sure, and will hope they donít die after less than 3 minutes run time LOL

    Thank you for the help! The bypass and lack of a strong pisser freaks me out


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  6. #6
    Top Dog JC-SuperJet's Avatar
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    Re: Forgive me ... but dual cooling off the head from a single inlet ...

    If the Outboard Bypass was on the TEE Straight Thru Leg, the path of least resistance, more water would come out of the Pisser.

    But it's on the Branch Leg, so most of the Water is going to the Stinger.

  7. #7
    Resident Guru bored&stroked's Avatar
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    Re: Forgive me ... but dual cooling off the head from a single inlet ...

    Quote Originally Posted by fastgtfairlane View Post
    If you only have one line going in, you should have one line coming out.
    That's absurd.
    Reducing the restriction on the outlet only lets the inlet move the max amount of water it can. I've run single in/dual out setups on all my standups and sitdowns without issue for almost 2 decades here in AZ with massive heat in the air and warm as hell water too.
    '96 Suuuperjet: 84mm 61x, ported, B-pipe, Dual 44's, Newmiller head 220psi w/girdle, Skat big hub, footholds, AMG green hell mango matte.
    '95 Raider 701: Fiberglass not SMC, Hydrotrailer hitch, ugly purple and yellow everywhere.

  8. #8
    PWCToday.com Is My Home Away From Home fastgtfairlane's Avatar
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    Re: Forgive me ... but dual cooling off the head from a single inlet ...

    If the water is moving too fast through the engine, it may not properly pick up enough heat from the engine. One inlet in and 2 going out seems useless to me as 1 line can only move so much water so 2 outlets seems redundant. But I'm happy you've done this redundancy for decades. That's great for you. My point is that one inlet and 2 outlets is not necessary.
    96 superjet- rockered, -4, wide tray, adjustable footholds, kv148 mag setback pump, skat 7/14 impeller, rrp adjustable pole, blowsion ovp steering, 62t/62t, ada head, zeel A02T cdi, dual 44s, boysen power reeds, TNT SS chamber

    93-x2, newmiller ported SP750, milled head, R&D single 46 intake, sbn46, fpp blaster chamber pipe, hooker 9/15, umi, rhaas squirrel cage, dakine foot straps

  9. #9
    Top Dog JC-SuperJet's Avatar
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    Re: Forgive me ... but dual cooling off the head from a single inlet ...

    The Problem with the Cooling Water from the Pump is that it's aerated, meaning it's full of Air Bubbles and is not a Solid Consistent Full Stream of Cold Water Circulating thru the Engine like most imagine.

    Thus Cooling Water Transit Time does matter as related to Heat Transfer from the Aluminum Castings to the Cooling Water.

    How many Cooling Inlets versus Outlets is debatable. Also depends on the Pipe and Cylinder Head Manufacturers' recommendations.

    Traditional Rule of Thumb has been One In-One Out and it's a good Rule for Most. Engine Builders and More Experienced Mechanics have there own Set-Ups that differ from the Rule of Thumb. Whatever works best.

  10. #10
    Resident Guru bored&stroked's Avatar
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    Re: Forgive me ... but dual cooling off the head from a single inlet ...

    So factory wave runner 760's [only 760 setup I've worked with] with a single line in, and dual out [1 going to pipe, one strait to pisser overboard] are a bad idea and Yamaha is wrong? I doubt that very much.
    '96 Suuuperjet: 84mm 61x, ported, B-pipe, Dual 44's, Newmiller head 220psi w/girdle, Skat big hub, footholds, AMG green hell mango matte.
    '95 Raider 701: Fiberglass not SMC, Hydrotrailer hitch, ugly purple and yellow everywhere.

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