SBT Jetski Engines, Parts & Accessories

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  1. #1
    Joined
    Aug 2007
    From
    NC
    Posts
    2

    Default 98 XP Exhaust hoses melting

    I recently purchased an xp and it starts and runs great, The rubber unions that attach the exhaust pipe to the manifold and the muffler keep melting and I lose power and start intaking exhaust, killing performance. I am under the impression that there is an issue cooling my exhaust (not a backfiring, pressure issue) but I don't know where to start to rectify the problem. For now, I just bring plenty of radiator hose (much cheaper than the seadoo union, and lasts only slightly less), But I do need to fix the problem. Are there any manuals you can suggest or procedures that will work to fix it? I have gone on parts websites and have become familiar with the cooling system parts but where do I start?
    Thanks
    Seawolfe

  2. #2
    Joined
    Jul 2007
    From
    toledo
    Posts
    17

    Default Re: 98 XP Exhaust hoses melting

    Hi sorry don't know the fix but I would not run a ski that got that hot I would be afraid of burning that motor up get a manual or a disc and it will show you the water flow I do know that if it has been modified that could make a difference too good luck

  3. #3
    Joined
    Aug 2004
    From
    Olympia, WA
    Posts
    3,629

    Default Re: 98 XP Exhaust hoses melting

    you have a clog in the cooling system. I would be checking the water reg on the waterbox as well. You need to fix it. constant overheating of the cooling system will only lead to complete failure of the motor.

    Also, take off all your cooling lines and blow through them with a compressor.
    Dan Solie -
    04 RXP (the "Instigator")
    94 xp (freestyle mods)
    95 xp (faster than the 94)
    JS550 (the toothpick & the loaner)

    For FREE Seadoo Manuals - Click HERE!!!!

    http://www.tripleateam.com/water/v/U...ery/Dan-Solie/

    **** Please do not PM me. I don't do PM's.... Please post your question on the correct forum so that all can see and learn. Thanks! ****

  4. #4
    Joined
    Nov 2003
    From
    Glendora, CA
    Posts
    6,846

    Default Re: 98 XP Exhaust hoses melting

    The water regulatr on the muffler is shot. Open it up and see if the clamp is off the diaphram, or maybe you just need a new onne.

    Part of the job that the WR does is keep couplers and hoses from melting.

    If the engine or exhaust pipe was recently replaced, they may have mixed up the waterlines at the mid pipe, One from the WR and one that goes overboard.
    Bill O'Neal <br>
    WCM
    <a href="http://www.watercraftmagic.com"

  5. #5
    Joined
    Aug 2007
    From
    NC
    Posts
    2

    Default Re: 98 XP Exhaust hoses melting

    OKay, so i checked the lines and they go to where they are supposed to, I opened the water regulator and the clamp is on, but I don't know how to check if it is bad or good, I blew air through the cooling lines and they are clear.

    After tracing the water lines and looking at it for a while, i think I see how she works, correct me if I am wrong, but the water is pushed in just behind the impeller and heads up to the engine compartment and then tee's, with one line going to the cylinders and the other going back to the water regulator. The water regulator is basically a thermostat, when the muffler warms up the WR opens and lets water from the hose I just spoke of through to a hose that runs up to the exhaust manifold on the stern side of the manifold. The water then surrounds the exhaust and leaves the manifold via the two hoses that exit the hull on the port side. Still can't figure how the Garden hose supply connection that goes to the underside of the manifold figures in but it seems I can only check the water regulator on the lake.

    If I put the ski on the lake and take off the hose from the WR that attaches to the exhaust manifold it should have water flowing through it as soon as the motor warms up. Will this tell me if the WR is good or is there another way?

  6. #6
    Joined
    Nov 2003
    From
    Glendora, CA
    Posts
    6,846

    Default Re: 98 XP Exhaust hoses melting

    Quote Originally Posted by Seawolfe
    OKay, so i checked the lines and they go to where they are supposed to, I opened the water regulator and the clamp is on, but I don't know how to check if it is bad or good, I blew air through the cooling lines and they are clear.

    After tracing the water lines and looking at it for a while, i think I see how she works, correct me if I am wrong, but the water is pushed in just behind the impeller and heads up to the engine compartment and then tee's, with one line going to the cylinders and the other going back to the water regulator. The water regulator is basically a thermostat, when the muffler warms up the WR opens and lets water from the hose I just spoke of through to a hose that runs up to the exhaust manifold on the stern side of the manifold. The water then surrounds the exhaust and leaves the manifold via the two hoses that exit the hull on the port side. Still can't figure how the Garden hose supply connection that goes to the underside of the manifold figures in but it seems I can only check the water regulator on the lake.

    If I put the ski on the lake and take off the hose from the WR that attaches to the exhaust manifold it should have water flowing through it as soon as the motor warms up. Will this tell me if the WR is good or is there another way?
    No you got it all wrong. The WR uses water pressure from the jetpump to move the valve in the WR to adjust the amount of water that goes into your exhaust pipe to keep the pipe and hose couplers at a safe tempature so the hoses don't melt.

    A water regulator can be bad even though it "looks good".

    The WR sends a full stream of water into the pipe fitting only when the motor is running at low to midrange rpm, then as the rpm increases, the water being sent into the pipe is diminished with the majority of it being put into the muffler. This allows the exhaust system to produce a better sonic wave to pack the clyinders ( The effect of a good tuned pipe on a two stroke motor) so that the engine can run more rpm and produce more power, and still have a very strong bottomend punch for the initial accelleration of the hull.

    The only way to know the water regulator is working properly is to hang the hose where you can see it and run the boat in the lake while viewing the water flowing from the hose. You want to see a full stream of water from the hose at low rpm, then watch that water flow decrease as the rpm gets up there in the upper ranges of the rpm band.
    What is happening is the water pressure from the jetpump is increasing with the rpm of the motor and overpowering the spring in the water regualator, and diverting the water away from the exhaust pipe and into the muffler.

    This cannot be duplicated by connecting a garden hose to the back of the ski, as it needs the water pressure produced by the jet pump to make the valve work as it should.
    Bill O'Neal <br>
    WCM
    <a href="http://www.watercraftmagic.com"

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