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  1. #1

    MSX 140 Overheated- then no power and SLOW mode

    I have just had an MSX140 in at work that has had some issues. It came in with the customer complaining that it had no power and would't rev over 3500rpm. He went on to explain that he had been riding it all day then all of a sudden the engine light and the temp warning light came on the MFI. He then lifted the seat and saw some smoke come out and the engine would no longer turn over. he took it somewhere and had the starter motor replaced. The next time he took it out it wouldn't rev over 3500rpm. As it was Christmas and most places were shut, he traveled 2 hours to bring it to me.

    After checking the basics I checked and cleared the codes(43 was present along with about six others) and took it to the river. Once on the water the ski would not rev over 5000 rpm. I took one lead(wire) off at a time and tested how it ran on 2 cylinders. what this showed is when running on 1 and 2 or 1 and 3 the engine would not rev over about 3600rpm. But if you ran it on 2 and 3 it would rev to 5000rpm. This indicated that number 1 cylinder was not running properly.

    Next another compression test was done(had already done one) and the results were,1-115,2-120,3-125. Didn't seem to bad but I noticed some water on the plug-bingo!

    After taking it back to the workshop the number 1 head was removed and the head gasket o-rings were melted along with some wires and hoses resting against the head.I needed to know why it had over heated so checked the cooling system and found the thermostat had failed and the by-pass valve had siezed.

    Once eveything was replaced and the head was faced I took it out this afternoon for a test on the river, it ran great. It made it to 6900 rpm and other than water leak from the flush hose fitting had no issues. Lets hope the owner can enjoy whats left of his holiday.

    I hope this thread helps someone else figure out whats wrong with there ski and thanks again to k447 for his helpful pm's

    Nathan


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Glad to hear you got it sorted out

    As we discussed previously, these Ficht fuel injected engines can also suffer from the usual array of mechanical problems. Every Ficht engine with a problem is not necessarily a Ficht problem.

    When working on a Ficht engine, always check the mechanical aspects, just as you would on a non-Ficht engine.

    The EMM trouble codes can provide some diagnostic clues, but do not reply only on the trouble codes alone. The Ficht EMM has a limited ability to diagnose problems, and sometimes the stored EMM codes are only part of the story, or even not the important story.

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    bowsniper's Avatar
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    Excellent diaganosis and fix there you guys! Way to go in finding out what actually caused the issues in the first place.. Great Job! Is the Pto the one thats gonna go first with a bad thermostat and/or bypass valve? or was that just an anomoly? any of them could of cooked?

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    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by bowsniper View Post
    ...Is the PTO the one that's gonna go first with a bad thermostat and/or bypass valve?

    or was that just an anomaly? any of them could of cooked?
    In this case I believe it was the MAG cylinder ( #1 ) that suffered the most from the over heat.

    I image the other cylinders also became quite hot, but apparently not enough to cause those cylinder head o-rings to fail.

    BTW, with the Ficht engines Polaris recommends keeping the thermostat in place and operational. Apparently the Ficht engines prefer the controlled temperatures that the thermostat provides.

    This is different from the carburetor engines, which often will run quite happily with the thermostat removed (unless the lake water itself is very cold).

  5. #5
    Also, the thermostat is right near the #1 cylinder and the furthest point away from the water supply coming from th jet pump so it would make sense that it would get hottest there. The actual head paint has discolored and the serial number sticker is black so that was another indication.

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    Connecticut CrazyA's Avatar
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    Quote Originally Posted by DRIFTER View Post
    Also, the thermostat is right near the #1 cylinder and the furthest point away from the water supply coming from th jet pump so it would make sense that it would get hottest there. The actual head paint has discolored and the serial number sticker is black so that was another indication.
    The pump actually feeds the exhaust pipe which then feeds the motor from the center, so once your system is full, the mag cylinder is receiving water as quickly as the pto.

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    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by DRIFTER View Post
    Also, the thermostat is right near the #1 cylinder and the furthest point away from the water supply coming from the jet pump so it would make sense that it would get hottest there.

    The actual head paint has discolored and the serial number sticker is black so that was another indication.
    For those who are not familiar with the MSX 140 Ficht fuel injected engine, the thermostat housing on the MSX 140 is at the front of the engine, near the MAG (#1 )cylinder.

    This is different from the Polaris carburetor engines which typically have the thermostat housing at the rear of the engine near the PTO cylinder.
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    bowsniper's Avatar
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    ok then, why did the mag burn when they both get equally cooled? a restriction possibly? must be a flow issue when the stat or relief died huh?

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    Connecticut CrazyA's Avatar
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    I didn't say they were both cooled equally in this case.... I said the water supply is reaching the mag and pto at the same time.

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    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by bowsniper View Post
    ...why did the mag burn ... must be a flow issue when the stat or relief died ...
    If both thermostat and pressure bypass plunger are stuck closed, then when the jet pump pressurizes the cooling system, there is very little or no flow. The air in the engine cannot get out, so there is a trapped air bubble between the incoming water and the thermostat housing.

    I could imagine that a trapped air bubble in the cooling jacket would tend to affect the MAG cylinder the most since the engine angle puts the MAG cylinder slightly higher.

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