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  1. #1
    steve45's Avatar
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    Need Help With Overheating Ultra LX

    Had trouble earlier this week with an Ultra LX (NA engine) running fine at cruising speed, but it would overheat when we got to a no wake zone. Found sea grass once, but it happened several times. I have previously installed inline strainers to reduce the sea grass problem that we've had in the past. When we got home, I pulled the strainers and found brown residue (silt?). Cleaned the screens and re-installed.

    Today the same thing. Ran fine at cruising speed, went about 30 miles no problem. Got back to no wake zone and it stopped pissing and overheat warning came on. No grass in the jet pump, got to shallow water and pulled the screen on my strainer and it was clean as a whistle. Removed the screen and ran it like that. Ran fine at cruise, slowed to no wake speed and it stopped pissing and overheated again.

    This seems bass-ackwards to me, seems like if I had a problem that it would show up at higher speeds and work fine at idle.

    Any ideas?


  2. #2
    Formerly Ultra250 TN Aquaholic6801's Avatar
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    Pull the water intake on the top of the pump and see if it's blocked

  3. #3

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    Also check the water outlet pipe under the Intake. I'm not sure what year you have but the early ones would corrode badly. The design was changed a bit in later models.

  4. #4
    steve45's Avatar
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    Thanks, guys! I had another thought last night.

    After reading the thread about hydrolocking the Ultra LX engines and the changes to the exhaust system that may have contributed to it, I recently added the reed valves to mine, like what was used in the earlier models. This is nothing more than a rubber flapper valve that helps to keep water from entering the waterbox and working it's way back into the engine.

    My theory is that this flapper valve increases the back pressure on the exhaust, causing exhaust gases to flow back through the cooling lines at idle. At higher power settings, there is enough flow out the exhaust to fully open the valves, and enough flow from the jet pump to keep the system full of cooling water.

    It's very easy to remove the valves (3 bolts), so I'll try that today. I'll let you know how it works tonight.

  5. #5
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Quote Originally Posted by steve45 View Post
    Thanks, guys! I had another thought last night.

    After reading the thread about hydrolocking the Ultra LX engines and the changes to the exhaust system that may have contributed to it, I recently added the reed valves to mine, like what was used in the earlier models. This is nothing more than a rubber flapper valve that helps to keep water from entering the waterbox and working it's way back into the engine.

    My theory is that this flapper valve increases the back pressure on the exhaust, causing exhaust gases to flow back through the cooling lines at idle. At higher power settings, there is enough flow out the exhaust to fully open the valves, and enough flow from the jet pump to keep the system full of cooling water.

    It's very easy to remove the valves (3 bolts), so I'll try that today. I'll let you know how it works tonight.
    That probably won't change anything. Are you getting oil temp or overheat warnings? The overheat is on the exhaust side oil temp is in pan.

    If you got silt in the strainer, its probably plugged the stator cover. I would try and flush that first.

    Did yall flush it on the hose after riding it the other day?

    Are you getting water out the pisser at idle?

    Sean

  6. #6
    steve45's Avatar
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    Flushed well after each outing.

    It started working normally today after removing the reed valve in the exhaust, but started acting up this afternoon. Ran good, but when we got close to port and slowed down, it stopped pissing again and blew steam out the pisser and got the overheat warning. There was a little bit of sea grass in the intake grate, but not as much as the other 'Ski that ran normally.

    I'll take a look at it tomorrow. LOOOONG day today, 68 miles in 4+ hours of riding. About 40 miles of slogging through 3+ foot waves, 20 knot winds with wives on board. Used 19 gallons of gas in each 'Ski (3.5 MPG). Glad we stopped and filled up at 28 miles!

  7. #7
    I did a beach launch once and when I got to back line there was no water flowing out the pisser during idle, when I revvd it hard enough the water would come. I didnít take any chances out at backline, so I shut the ski off and blew really hard with my mouth into the pisser. It cleared out whatever was there causing intermittent blockage because when started it up it was fine again. I think it was a grain of sand or small stone that I must of picked up while launching from the beach.

    Worth a try blowing on that pisser. Maybe try even remove the pisser hose at the exhaust and blow it through so you can check if something does blow out.

  8. #8
    steve45's Avatar
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    I'll have to give that a try, Blake. We did anchor the 'Skis yesterday and the tide went down, causing them to drag on the sand. I don't have an air compressor with me this week, so I'll see if I can blow it out by mouth.

    I did remove the strainer from the jet pump this morning and there wasn't a spec of dirt in it, the elbow fittings were clear, too.

    Too rough to ride today. Hope we can try it tomorrow.

    Thanks for the idea!

  9. #9
    Let us know how it goes. Keen to know what you discover.

  10. #10
    steve45's Avatar
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    Too nasty to ride on Saturday, as well. 25-30 knot winds, 3 foot waves, sea grass everywhere. Vacation is over, drove home today. I plan to take them to the lake next weekend and run them in fresh water to get them good and clean. I'll report back then.

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