CMI Big tubes getting discolored on the very top
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CMI Big tubes getting discolored on the very top

  1. #1
    Senior Member Skydog's Avatar
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    Default CMI Big tubes getting discolored on the very top

    Water PSI good (17PSI when running hard) do i just not have enuff water volume? Or could i be reading air psi? I have water pickup on the bottom of the boat.

    Thank you

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    Senior Member renodaytona's Avatar
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    How is your cooling system set up besides the pick up on the bottom of the boat? Do you have a H2O pump and does it feed the engine? Where does your exhaust pull the H2O from? Do you have closed cooling on your engine? What does the H2O flow look like out the exhaust while running?

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    Senior Member Skydog's Avatar
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    Quote Originally Posted by renodaytona View Post
    How is your cooling system set up besides the pick up on the bottom of the boat? Do you have a H2O pump and does it feed the engine? Where does your exhaust pull the H2O from? Do you have closed cooling on your engine? What does the H2O flow look like out the exhaust while running?
    Yes comes in boat too belt run single pump to oil cooler in front of motor out intake to headers. I was thinking maybe put a little restriction in the back to lower headers to help force more water up two the top two headers? On the water manifold right below each header.

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    Senior Member renodaytona's Avatar
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    Seems as though there is not enough water running through the system I think restricting it will only cause more problems.

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    Senior Member Hullshot's Avatar
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    17 PSI at WOT? We can assume you have a pressure dump on it then, or you havent changed the impeller in a long time? Did you ever have an impeller that broke up on you then replaced it?

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    KAP
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    Hey Don:

    Hope all is well.

    I have the same issue with my Big E-Tops I have been meaning to send them in but due to the boating season being in full swing.

    I decided to wait a little longer.

    One tube has tremendous discoloration and it looks like the discoloration went up the tube kinda like hot spots.

    KAP
    One man with courage is a majority.
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    www.dougwrightwest.com Home of X-treme Outboards

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    Senior Member Hullshot's Avatar
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    Quote Originally Posted by KAP View Post
    Hey Don:

    Hope all is well.

    I have the same issue with my Big E-Tops I have been meaning to send them in but due to the boating season being in full swing.

    I decided to wait a little longer.

    One tube has tremendous discoloration and it looks like the discoloration went up the tube kinda like hot spots.

    KAP
    Sounds kinda like the inner tube is too close to the outer tube and not allowing adequate flow or cooling around tube? Or something got in that one tube and is restricting water flow? Measure the temp around with a infared gun and check for hot spots?
    Last edited by Hullshot; 08-02-2011 at 03:03 PM.

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    Senior Member Skydog's Avatar
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    Well guys one thing I should make clearer. My water pickup is on the transom the real bottom of the boat where drain plug is like 2 feet in front of pickup. So I bet I am getting lots water with air in it. So going to add a water pickup in the very bottom of the boat. Hope this helps..... What u guys think

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    Senior Member Teague Custom Marine's Avatar
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    Hey Skydog,

    I have seen that Big Tubes are notorious for discoloring, sometimes it will just happen because. It can be either from the water pump, water flow, or the way your tails dump the water into your exhaust. At 17PSI you are fine with you water pressure, lets see if you can restrict it back at the headers a bit more? Are you picking up water from your drive and an addition pickup? You might need a larger tube in your pickup? Has this always been a problem or is it just starting to happen?

    One thing you can do is go to a 2 stage pump and pump the headers with there own source and restrict the engine off its own water dump. We have a few customers with carb engines with big headers that run them that way.

    Give us a call and we can help work to resolve this problem! SS headers look way better when they are that nice shinny, polished color!

    Eric
    TEAGUE CUSTOM MARINE
    661.295.7000
    Teague Custom Marine Home Page


  12. #10
    Senior Member Skydog's Avatar
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    Thank you for all your help i did put your water pickup in bottom of the boat. And i feel the problem is fixed. But only running the boat will tell. I will update after a few times out, if the snow is not flying frist....

    Thank you Skydog

  13. #11
    Senior Member Hullshot's Avatar
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    you merc pump will do just fine

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