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  1. #1

    Overheated Polaris MSX 140 - Please help?

    Hi all,

    I just needs some advice in regards to my ski Polaris MSX 140. I had it out 3 months ago and noticed that the engine light had come on. I immediately headed to land and noticed that the oil pickup lines and cap had come off inside the hull meaning that oil was splashing out to the point that none was left.I put the cap back on and got a friend to go get more oil so that i could ride it back to where the trailer was parked etc.

    Upon setting off the engine light was now off but 2 minutes after setting off the engine beeped and then i noticed smoke coming from below.

    I had to be towed back to were my trailer was parked (I turned the inlet valve off).

    A week later I had the cylinders inspected with a camera and the compression tested by a mobile jet ski mechanic. There was no water in them and there was no scoring. He was actually pretty impressed with the cylinders condition and the the quality of the cross hatching etc. He sprayed in some oil through the plug holes and tested compression. Can't remember the readings however one cylinder was down, but still at a reasonable level he said. Biggest thing is we couldn't fire it up because there wasn't a spark. He said the EMM was most likely overheated.

    This was 3 months ago and i haven't been able to get someone to fix the EMM locally (still looking in Perth Aust). I will probably buy one from BABBITTS however still don't have anyone to load the injector info.

    My main concern is that I have not been able to flush out the water that was in the ski the day of the incident. Will there be damage to the ski and is there a way i can get the water out without starting it? I have no idea of how the cooling system works etc. I do still have the inlet valve turned off since towing it etc.

    I am no mechanic and would appreciate your advice.

  2. #2
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Welcome to the Hulk

    Perth? Try sending a Private Message to Bernie

    You certainly can flush the engine cooling system without running the engine. Locate and disconnect or clamp off the small cooling water hose that runs between two fittings on the exhaust pipe. That is the only place where cooling water gets injected into the actual exhaust system.

    Now you can connect your flushing garden hose and flush the engine. Since it has been sitting for months, and I presume it was saltwater you were riding in, I suggest you use a product like Salt-Away to help clear the salt residue.

    Also remove one or both of the large hoses from the water box and draw out the salt water.

    While you are in there remove and check/clean the fittings attach to each end of that small exhaust water hose. One is a mesh screen and the other is a restriction orifice.

    I do not understand how the loss of oil into the hull could cause an engine or EMM overheat. Certainly a lack of oil would cause increased wear of the cylinder walls, but it would not affect the EMM.

    Inspect the very small water cooling hoses and fittings that feed the EMM and the cover of the flywheel housing. That circuit must freely flow water through the EMM and then exits at the rear hull exhaust fitting. Be sure to check the elbows at the flywheel cover.

    Also inspect the small black plastic mesh screen hidden inside the jet pump nozzle.

    Did you happen to run the engine in very shallow or sandy water? Wondering if you might have pumped sand into the cooling system.

  3. #3
    Thank for the advice K447.

    I will look at it in the morning and see if i can drain the water.

    I took the EMM off and notice some corrosion around the water inlet. I also had a look at the back of the circuit board in it and took a close up pic. Picture attached.

    In regards to the shallow water question, i didn't run it in shallow water. The day it all happened however it was quite rough and the area i near where I was pulling in had lots of leave and small debris floating on the water.
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  4. #4
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    That EMM may have over heated. It may be repairable.

    Otherwise, you now need either a new EMM and a shop with Digital Wrench to transfer the injector compensation maps from old EMM to new EMM, or you need another good used MSX 140 EMM and the matching injectors.
    Last edited by K447; 08-12-2013 at 07:49 AM. Reason: EMM CPU chip can look bubbled under the gel normally

  5. #5
    A) Before i can flush it I need to get the remaining thread out from where the inlet hose broke off under the pressue of the water when it overheated. I can then install the new one.

    B) Can you please clarify if this is the hose you are referring to?

    C) When the hose is then connected where does the water go along this mark here? Does this simply circulate around the engine.. This part i would love to know? And if so where does it exit?

    I have been looking at page 82 to trying to work out the flow of water. Its not that i don't trust you I just want to make sure I have right hose before I add the hose to it etc.

    I have attached the service manual in which i am referring as well as the pic that the letters correspond to.
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  6. #6
    Click avatar for tech links/info K447's Avatar
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    Jul 2007
    near Toronto, Canada

    Arrow Normal cooling water flow for the MSX 140 engine

    This is how the normal water flow works when the MSX 140 hull is in the water with engine running.

    The B hose in your marked photo is indeed the small cooling hose that injects water into the exhaust pipe. When you remove the small hose from the brass fitting shown in your photo, the fitting can be unscrewed to reveal the mesh filter screen (which should be clean). I have marked this small hose in pink.

    Regarding water flow during normal engine operation, see the attached diagram. Cooling water feed from the jet pump base comes in via the 3/4 inch hose (shown in green).

    Blue shows the distribution of cooling water into the exhaust manifold (small hose) and exhaust pipe water jacket (this is the main cooling water flow path) and also the small hose feeding into the flywheel/stator cover.

    The water flows into the exhaust cooling jackets, then flows into the engine cylinder water jackets via the exhaust manifold to cylinder mating (exhaust manifold water jacket to into all three cylinder water jackets).

    The cooling water then flows through the cylinder water jackets and up into the cylinder head water jackets. The water then exits the cylinder heads up into the water manifold bar, which you have marked as C.

    Normal cooling water bar flow is in the reverse direction of your arrow. It flows through the water bar and into the thermostat housing. From there it exits down and flows towards the hull exit fitting at the rear of the hull.

    * Unique to the MSX 140 is another water exit from the exhaust pipe, which feeds into a special water fitting on the front of the waterbox. This is also a 3/4" hose.

    There is also a small diameter hose which feeds into the bottom of the exhaust manifold at the PTO cylinder. I suspect this hose primarily serves as a drain hose to prevent freeze damage during storage.

    The cooling water flow for the EMM first flows through the stator cover, then through the EMM. From there it travels to the hull exhaust fitting at the rear of the hull, where it gets dumped out with the exhaust gases.

    There are a total of four places where cooling water exits the MSX 140 system;
    - Water injection spray into the exhaust pipe inner chamber (shown in pink)
    - Water feed directly into the water box from exhaust pipe water jacket
    (water from both of these eventually exit with the exhaust gases out the rear exhaust fitting)

    - EMM cooling water small hose exit via hull exhaust fitting
    - Main engine water flow via thermostat housing and into jet pump tunnel fitting
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  7. #7
    Click avatar for tech links/info K447's Avatar
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    Jul 2007
    near Toronto, Canada

    Arrow Garden hose connections, Reverse flush and Forward flush (MSX 140) engine NOT running

    There are two approaches to connecting the engine to a garden hose.

    Reverse Flush

    The common garden hose connection is called Reverse Flush. The garden hose is connected to the water manifold bar, where you currently are showing the broken off fitting (A).

    When connected here, the garden hose pressurizes the water manifold bar. The thermostat limits the flow of cold water out the normal water exit hose, so the majority of the water is forced backwards through the engine.

    Note: All Ficht fuel injected engines are specified to have the thermostat in place.

    Reverse flow water travels down into the cylinder heads and cylinders, then into the exhaust manifold. From there the water eventually gets dumped out the jet pump cooling water inlet fitting (via Blue and Green hoses). The jet pump cooling water inlet is a small black plastic mesh screen which is tucked into the inside of the jet pump exit nozzle (right hand side).

    Note that with reverse water flow, the hose tee connection for feeding the EMM will see very little water pressure because the water at that point has a large 3/4 inch hose flowing out through the jet pump with little back pressure. The result is that the EMM sees little or no water cooling during reverse flush water flow.

    Note: This is not a problem when the engine is not running, but it does mean that the EMM really isn't getting flushed out.

    If you disconnect or clamp off the pink hose, then the pressurized water in the exhaust pipe water jacket cannot inject into the inner chamber of the exhaust system. This is the only place where water could possibly reverse flow back into the engine.
    *Water box connection?

    Forward flush water connection

    An alternative to reverse flush is to feed the garden hose water into the same 3/4" hose that the jet pump normally feeds.

    This is the large hose connected directly to the nipple on the base of the jet pump (see attached photo). When standing on the rear deck, it is down low on the right side of the drive shaft through-hull bearing, but farther back.

    Note: The foam battery box makes it hard to get at the hoses. There is a hose tee right in front of the pump nipple, so little room to work down there.

    Remove the hose from the pump nipple and install a garden hose adapter onto the hose end. Now you can connect your garden hose and run water through the cooling system in the normal direction.

    Since you will be doing this with the engine not running, you still need to clamp off the pink hose in the diagram to keep water out of the exhaust inner chamber (and the engine itself).

    Edit: because there is another large hose feeding into the exhaust waterbox, down low on the front of the waterbox. I cannot say how quickly the waterbox will fill when the garden hose is connected. If it fills quickly then the water could backflow up the exhaust and into the engine. To be safe, this stubby large hose also needs to be clamped off before flushing with the engine not running.

    Note that the thermostat will not be open because the garden hose water is cool. This means that there will be minimal water flow until the garden hose pressure is high enough to open the pressure bypass inside the thermostat housing. You will know this is flowing by the amount of water coming out the hull exit fitting inside the jet pump tunnel.

    The EMM will also have significant water flow since it is tee'd off the garden hose feed. You will see the EMM water flow coming out the exhaust fitting on the left rear of the hull.

    Once you have finished flushing the engine, if there is salt water in the waterbox, or you just want it dry, remove one or both of the very large rubber hoses from the water box. You can then use a wet vacuum to draw the excess water out. Or you can just remove the waterbox entirely and dump the water out.
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  8. #8
    Click avatar for tech links/info K447's Avatar
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    Arrow Preparation for in-water towing of disabled MSX 140

    All Polaris watercraft require the cooling system water feed to be shut off before towing. This prevents water from accumulating in the exhaust system and back flooding into the engine itself.

    Note: If this is not done and you suspect the engine may have been flooded with water during towing, do NOT attempt to start the engine (do not even touch the start button). Instead, promptly review the procedures for recovering from a water flooded engine. Do not let a flooded engine sit with water inside for any length of time, lest the engine will rust and need major repair.

    In the case of the MSX 140 the water cooling feed hose is buried down beside the foam battery and EMM box, and the actual hose you want to clamp is only a couple of inches long (see green arrow in photo)

    Click image for larger version. 

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    The faster you tow, the higher the water pressure coming in from the jet pump (even though the engine is not running) and the faster water will flow into the exhaust system. This is why you want to clamp off the water feed before towing.

    It appears Polaris located that first tee way down there near the jet pump nipple in order to maximize water drain back during storage and prevent water freeze damage during the winter.

    What it does is make it difficult to fully clamp off the water feed before towing.

    If you only clamp the large hose up higher near the engine, it is unclear how rapidly the small water hose will back flow through the exhaust water jacket and water box.

    My recommendation is to clamp two hoses on the MSX 140 before towing.

    The first is the large 3/4" hose where it rises up to connect into the large exhaust pipe.

    The second is the small hose which connects to the exhaust manifold right beside the PTO cylinder.

    Both are show in light blue in this diagram.
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    Locate each of these hoses beforehand. One method is to wrap a few turns of red tape around each hose where the clamp pliers would go. That way when you are on the water there will be no confusion regarding which hoses must be clamped.

    Don't forget to actually put the hose pinch pliers into your storage bucket

    Remove the hose pinch after towing, before you run the engine.

    Some owners will install shut-off valves inline in these hoses. This makes it easy to shut off the water when needed before towing, but you must ensure the valves are turned ON before you run the engine.

    An alternative is to clamp off the actual water injection spray hose, which loops across the top of the large exhaust pipe. It is the smaller diameter hose shown in Purple in this diagram.
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    This will avoid water accumulation inside the exhaust pipe, but will not prevent the waterbox from being filled during the tow.
    (The waterbox has a direct cooling water feed hose, down very low at the front, visible in this photo)
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    It will also not protect the hull from flooding if there is a breach of the cooling system (disconnected hose, etc).

    If the cooling system hose(s) cannot be pinched/blocked before towing, then tow at a walking pace. At very slow speeds the cooling system should not pressurize from the non-running jet pump

    This is the hose pinch clamp I have been using. It is called the WeLoc Gripper PA 100 and is made by WeLocUSA.

    If you use this clamp, you must lock the clamp release after clicking the clamp tight on the hose. Otherwise it can work loose during the tow.
    The primary complaint I have with this clamp - it can be tricky to get the recessed lock dial turned into lock position.
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    Last edited by K447; 09-09-2013 at 09:40 PM.

  9. #9
    This is a very thorough explanation, Thank you I can now understand how it all works . My only concern now is the other section you posted about, the back flow of water when towing. I only had the one tap turned off when this occurred but we weren't being towed fast.

    I have contacted Bernie and he has a Wrench to help with the EMM etc. Once again thank you and I will keep you posted on the outcome.

  10. #10
    Have successfully flushed the ski without starting it!

    Was a heap of shells and sand in the system. I think when i get it up and running again i would like to flush it this way more regularly as it got a heap more out of it. Actually a little baffled at how some of the debris came back out of the inlet pickup as the shells were reasonable size.

    I think this may have been the cause of the overheating and maybe the oil was just a co-incidence etc.

    I will have to investigate the rest of the cooling system as you mentioned earlier and will also check the thermostat etc.
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