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  1. #1

    Stx15f hot waterbox

    For all those that run a second waterbox delete in their 15F, how hot does the waterbox get and how hot does the top of the motor get where the plugs go through and the oil cap screws on to?

    My waterbox gets pretty hot pretty dam quick. So does the top part. Also the part that has 4 bolts that bolt on to the exhaust manifold (I believe) and the opposite end of the blue coupler toward the front of the ski is leaking a bit. I want to replace that gasket and seal it better but how bad is it that it leaks? Not a steady drip at idle but if I watch it for a while it's noticeable (watching while running it on trailer at launch)

    I run a Riva power air filter and a solas 13/19 prop

    TIA

  2. #2
    deksea's Avatar
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    This mod should not change the operating temperatures of the engine or the remaining waterbox. In other words, it should not reduce the volume of water through these components. No properly engineered modification to any ski is going to do something that stupid. If you just installed this mod and now you are noticing an increase in temperature, then its likely that some aspect of the actual installation of the mod has created a problem. If the suspected temperature issue already existed prior to the mod, or the mod has been in place for a while and now all of a sudden the issue has surfaced, then most likely there is no relationship between the issue and the mod. Generally speaking, the valve cover (you refer to it as the top of the engine) is going to be too hot to keep your hand on after the engine gets to operating temperature. The waterbox, although it will get warm, should not get so hot that you cannot keep your hand on it without burning yourself. And obviously it should not be melting the retaining strap and/or foam base. Assuming these components are operating hotter than normal, most likely a clog in one or more locations of the cooling circuit is restricting proper flow through the engine and exhaust. At trolling speed, if the water coming out of the bypass outlet (the "pisser") is extremely hot and/or mixed with steam, especially right after a high speed run, that is a good indicator you have cooling issues related to low flow from one or more system clogs.

    Systematically remove each hose and blow through it. Some will have water in them that you will have to purge while blowing through the line, but after the water is clear, all of these lines should allow you to freely blow through them. If this is not the case, then you are hot on the trail to locating the restriction. Common clog spots are the cooling water intake screen at the pump, oil cooler, stator cover nipples, return cooling manifold located on the block of the engine under the intake manifold, cooling connections at the waterbox itself, and pretty much any other elbow fitting in the cooling circuit, such as those located on the exhaust manifold. Again, check every hose meticulously and they should all blow freely.

    Regarding the suspected leak at the exhaust manifold gasket, verify its not actually a corrosion hole in the manifold itself. Regardless, any leak you've got anywhere in the engine compartment is bad and must be promptly addressed.

    Again, first thing to verify is proper flow of water though ALL lines in the cooling system. Are you religious about flushing the ski after use and avoiding running the ski in very shallow water and/or powering up onto the beach? Clogs can result from accumulated salt and sediment (improper flushing), but also from sand loading up in the system or a piece of crap sucked into the system while running in shallow, debris laden water.

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  4. #3
    Hi Deksea,

    I understand that any mods should not change many of the characteristics of a motor (i.e. make it run hot, etc.) and I get that if it did it could be due to user installation. I have been running this set up for quite some time now and just over the past while (this summer and last) it just appears to be running really hot (I could be just paranoid as I like to baby the ski). I will check the cooling lines in the mean time. Also, the retention strap and the foam that I can see have not melted. I feel that after all the time I have been running it it would have melted to the point of the strap snapping. There is no steam coming out of the side pisser, it comes out pretty warm but definitely no steam. When I do blow the ski out after pulling it out of the water and flip the throttle it does seem like steam comes out, with a bit of smoke (this could be due to hot temps exiting the ski and a slightly cool temperature as it was after dinner).

    I will have to check out the manual to make sure I don't blow out a cooling line and have whatever is in it head towards the motor, I will have to do some research on that one. Is the oil cooler the silver canister looking thing that it attached by two bolts on the exhaust side of the engine compartment on the side wall?

    I will unbolt the exhaust pipe at the exhaust pipe gasket and go from there. I will order a new one regardless since I am going to be taking it off.

    I am religious about blowing out the ski after every ride, typically right after I take the ski out of the water. I do not start the ski in the water in less than waist height depth and do not run it in very shallow water. If I do beach the ski i always walk it out into deeper water and rock the ski side to side and up and down at the rear of the ski to "flush" any sand particles out of the jet pump, etc.

    Another issue I have is that the ski would randomly shut off at idle - this has happened several times lately (at one point it didn't start and I think it could be the hot start issue). Some times it seems as though the ski is hard to start, at times. One particular incident happened when I jumped a wave. It died when I let my finger off the throttle so the RPMs wouldn't rev up while there was no load on the pump in the air. This typically happens when I just let off the throttle instead of slowly letting it off. Further, if I do release the throttle typically when the RPMs get close to idling I blip the throttle and it won't die.

    I am running the same plugs as last year as well. I need to change them.

    I also flipped the ski due to waves, I was off the ski trying to help my brother get on his as he was starting out in shallow-ish water is some rough, rough waves. As I got off the ski was parallel to the wave and a big one came and pushed the ski over. It was not upside down for any more than 5-10 seconds. Ran after that for a bit and didn't have any issues.

    I do ride the ski in fresh water only.

  5. #4

    Exhaust

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ID:	419727Does anyone have any tips on how to get the two bolts out of the bottom of the exhaust pipe?

  6. #5
    CJ River Rider's Avatar
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    Quote Originally Posted by polaris700man View Post
    Does anyone have any tips on how to get the two bolts out of the bottom of the exhaust pipe?
    Exhaust manifold has to be un-bolted & removed. I had to replace my exhuast pipe & blue coupler a couple of years ago and that was the only way I found to get it off.


  7. #6

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    Quote Originally Posted by CJ River Rider View Post
    Exhaust manifold has to be un-bolted & removed. I had to replace my exhuast pipe & blue coupler a couple of years ago and that was the only way I found to get it off.
    Yup.

  8. #7
    Quote Originally Posted by TJS0712F View Post
    Yup.
    Ok great thanks guys. Anything I should know about taking off the manifold? I ordered a new coupler, are the rings reusable to?

  9. #8
    deksea's Avatar
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    In my experience, I've found that unstrapping the waterbox, disconnecting the elbow, and moving the waterbox rearward out of the way and separating it from the exhaust pipe assembly saves a lot of time and frustration. Make damn sure you familiarize yourself with proper procedure and technique for re-installing the sealing rings.

    Sounds like you are doing all the smart things as far as caring for the ski goes. But from some of your questions above I can tell you are flying a little blind here and with this kind of work its time for you to graduate to a shop manual. Sit down and read this thing and you will truly be enlightened. Proper trouble shooting starts with full and correct understanding of the systems you are dealing with. Knowledge is power.

    https://www.manualslib.com/manual/78...i-Stx-15f.html

    Dave

  10. #9

    15f

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ID:	420629Yes I am definitely new to the engine scene, I've learned a lot, mostly about my other two skis which are two strokes. I looked at the manual, took off the hose leading to the bottom of the exhaust pipe, and the hose leading to the bottom of the exhaust manifold. Then removed the senor that lead to the rear of the manifold. Slid the waterbox back, unbolted the manifold, set it at the bottom of the ski, brought up the exhaust pipe and low and behold the 4 bolts I needed to remove. Did that, removed the manifold and pipe in two pieces, cleaned up very well where the gaskets go on the manifold to motor and pipe to manifold so that they are shiny. Took off the blue coupler which seems in pretty good condition still and realized I was missing a ring and a half. What would be the repercussions of missing those rings? They seem to have rotted off. I cleaned up the two ring slots with a wire brush and they're as good as new. The only thing I didn't order besides the coupler and two gaskets were those two rings so it looks like I'll be putting the repair on hold. Right now I have paper towel in the exhaust ports, taped it by blue painters tape. Should I spray some fogging oil in so the cylinders and crank won't rust due to humidity? It will probably take a week for the rings to arrive.

    In the picture it looks like the corrosion is all the way around the ports but it was and I cleaned almost all of it off. And the surface for the gasket is spotless. The nozzle you see is part of the vacuum so that all the bits that came off would be sucked up.

    I took the coils out of the plug holes so that they wouldn't be in the way. The paper towel is so that no debris falls down with the spark plugs.

  11. #10
    deksea's Avatar
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    "What would be the repercussions of missing those rings?"


    Without the rings in place, hot exhaust gasses will migrate past the sleeve connection of the exhaust manifold to water box inlet, and burn a hole in the blue hose connection. The reason that hasn't happened to you given the deteriorated condition of the rings as you found them is likely because salt and sediment had sealed up that area and was doing the job of the rings. Now that you've cleaned everything up , if you were to reassemble the exhaust/waterbox without rings your coupler would fail soon after you started operating the ski again.

    I wouldn't worry about fogging but it cant hurt. Looks like you did a nice job of sealing everything up and you're only down for a week anyway. This is a good time for you to go through all the segments of the cooling circuit and check for clogs. Also, pay special attention to the waterbox cooling connections. Salt and sediment can collect in there and inhibit water flow through the box and create a hot waterbox problem. You can have great flow through the rest of the system but a complete clog here all by itself will result in a seriously overheated waterbox. Sparse amounts of water coming from your exhaust outlet when you are flushing the machine is a good clue you've got a problem here.

    You might benefit from my experience in this regard:

    http://www.greenhulk.net/forums/showthread.php?t=260228

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