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  #1  
Old 06-07-2018, 05:55 PM
jj4smith jj4smith is offline
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MCX misfire causing vibration

This might be a long post-sorry.

We bought a 2011 X15 with MCX. The very first time out we hit a submerged log in 26 ft of water while surfing. There was a very minor bend in the prop, but it caused major vibrations. Got the prop repaired, and it now seems like we are having other issues.

The boat now has a bad vibration, but only at 1000 rpms. And, oddly enough, the vibration occurs both when the boat is in neutral and revved to 1000 rpms, and when the boat is in gear and revved to 1000 rpms(forward and reverse). No vibration or lack of power when accelerating quickly past 1000 rpms. Runs great at surf speed and wakeboard speed. Only notice the vibration when going slow to pick up somebody that fell.

Took the boat to a local guy and he thought the engine was missing on a cylinder. He changed plugs, and also noticed the timing was off so he adjusted the timing. Boat seems to run the exact same way after these adjustments.

Tried calling the not so local Mastercraft dealership and they canít get me in for another couple of weeks.

Anybody have any thoughts as to what this could be?


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  #2  
Old 06-07-2018, 09:45 PM
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Lars Lars is offline
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Did you have the alignment of the shaft checked after the impact? That and/or the strut would be my first thought.
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  #3  
Old 06-07-2018, 10:34 PM
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CantRepeat CantRepeat is offline
 
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Quote:
Originally Posted by jj4smith View Post
This might be a long post-sorry.

We bought a 2011 X15 with MCX. The very first time out we hit a submerged log in 26 ft of water while surfing. There was a very minor bend in the prop, but it caused major vibrations. Got the prop repaired, and it now seems like we are having other issues.

The boat now has a bad vibration, but only at 1000 rpms. And, oddly enough, the vibration occurs both when the boat is in neutral and revved to 1000 rpms, and when the boat is in gear and revved to 1000 rpms(forward and reverse). No vibration or lack of power when accelerating quickly past 1000 rpms. Runs great at surf speed and wakeboard speed. Only notice the vibration when going slow to pick up somebody that fell.

Took the boat to a local guy and he thought the engine was missing on a cylinder. He changed plugs, and also noticed the timing was off so he adjusted the timing. Boat seems to run the exact same way after these adjustments.

Tried calling the not so local Mastercraft dealership and they can’t get me in for another couple of weeks.

Anybody have any thoughts as to what this could be?


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The local guy noticed the timing was off? Did he know to the put the motor in diagnostic mode before checking or setting the timing? If not he just put your MCX out of time.

My guess is something else is bent in the running gear.

Who did your prop work?
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  #4  
Old 06-07-2018, 10:55 PM
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mikeg205 mikeg205 is offline
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Was the shaft checked for trueness? Is prop hard to turn prop by hand? But the vibration ik neutral is a concern... +1 on what cantrepeats says.

Sorry to read about your problem

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  #5  
Old 06-08-2018, 12:22 AM
jj4smith jj4smith is offline
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Originally Posted by mikeg205 View Post
Was the shaft checked for trueness? Is prop hard to turn prop by hand? But the vibration ik neutral is a concern... +1 on what cantrepeats says.

Sorry to read about your problem

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The prop is not hard to turn by hand, and itís equally as easy all the way around. Additionally, the local guy had me start the boat up out of the water and put it in gear for a second or two as he observed the shaft. He said it looked fine.

Not sure if the local guy put the motor in diagnostic mode before adjusting the timing. I will check on that.

The local guy had a guy that worked on the prop, but he had a hard time balancing it. He had to send it elsewhere to get the prop to balance.

If I have something wrong with the prop, shaft, or strut wouldnít it get worse at higher rpms?


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  #6  
Old 06-10-2018, 09:37 AM
jj4smith jj4smith is offline
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It is also worth mentioning the motor has a slight surge to it. You canít really notice it when the boat is at idle, but kick up he rpms just a tad and it gets very noticeable.

The BIG display does have an option to display current and previous engine codes. No codes are displayed.


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  #7  
Old 06-10-2018, 10:00 AM
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JimN JimN is offline
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Originally Posted by jj4smith View Post
This might be a long post-sorry.

Took the boat to a local guy and he thought the engine was missing on a cylinder. He changed plugs, and also noticed the timing was off so he adjusted the timing. Boat seems to run the exact same way after these adjustments.

Tried calling the not so local Mastercraft dealership and they canít get me in for another couple of weeks.

Anybody have any thoughts as to what this could be?


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Local guy THINKS it's mis-firing? It's not hard to find out if it is, or isn't. He should have done that before replacing ANYTHING.

The prop may have only had a minor ding, but the shock from hitting the log could have had a larger effect on the transmission and its alignment. Since the 1K RPM issue still occurs in neutral, it may not have done anything to the prop shaft, but the transmission input still rotates in neutral. Disconnect the coupler, move the prop shaft away and see if it still happens- if it does, the transmission has a problem. If it does, call your insurance agent.
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  #8  
Old 06-14-2018, 09:42 PM
jj4smith jj4smith is offline
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Thanks for the replyís fellas. Iím bringing it into the dealership in just a few days. Hopefully they can diagnose it! Iíll let you know what they find.


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  #9  
Old 06-29-2018, 02:27 PM
jj4smith jj4smith is offline
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So I took the boat into the Mastercraft dealership, and did a lake test with them. The tech said the MCX is known to have a rough spot. He said the engine seems to be out of balance right at about 1000 rpms. The tech also said he tested another X15 with MCX later that same day, and it had the same vibration right at 1000 rpms.

Just to clarify. The vibration is barely felt without the ballast full. However, with 2800# of ballast full it gets pretty bad. I'm pretty sure the small vibration is magnified several times over once the water ballast start vibrating with the engine. It really shakes the whole boat enough to drive me nuts.

Looks like some other folks back in 2010 had this same issue:

https://www.mastercraft.com/teamtalk...ibration+shake
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