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  1. #1
    Join Date
    May 2016
    Location
    Fargo, ND
    Posts
    127

    Default Thermostat Falure and Overheating Raptor Engine

    I was out surfing last weekend when my boat overheated. Ran for about 30 min before we lost power and shut the engine off. Blew the lid off the coolant reservoir. My raw water pump is working because I can see water running through my strainer. Had to get a tow in to prevent any damage. Dealer says it is the thermostat. Anyone else with a similar issue on the raptor 400? Roughly 270hrs.

    Boat ran fine the weekend before but we never ran it hard because there was still ice on the lake.
    2016 Mojo

  2. #2
    Join Date
    Aug 2011
    Location
    Commerce Lake, MI
    Posts
    2,145

    Default

    Quote Originally Posted by PuraVida View Post
    I was out surfing last weekend when my boat overheated. Ran for about 30 min before we lost power and shut the engine off. Blew the lid off the coolant reservoir. My raw water pump is working because I can see water running through my strainer. Had to get a tow in to prevent any damage. Dealer says it is the thermostat. Anyone else with a similar issue on the raptor 400? Roughly 270hrs.

    Boat ran fine the weekend before but we never ran it hard because there was still ice on the lake.
    Physically look at the raw water impeller and make sure it didn’t lose a cane and block the water line


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    2017 Moomba Craz

  3. #3

    Default

    Had the same problem and even though water seemed to be going through the strainer, the raw pump had failed.

    I had it replaced and all good so far.


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  4. #4
    Join Date
    May 2016
    Location
    Fargo, ND
    Posts
    127

    Default

    Thank you for the responses. I emptied the strainer and it filled almost instantaneously. Will hopefully know more soon.


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    2016 Mojo

  5. #5
    Join Date
    Oct 2017
    Posts
    9

    Default

    Did you find the issue? Mine overheated and went in limp mode yesterday. The raw water appears to be circulating fine but it continues to get hot. I checked the t star today and it appears to be working properly as well.

  6. #6
    Join Date
    Jun 2022
    Posts
    1

    Default

    How did you end up fixing this problem. I am having the same issue.

    Gene WB

  7. #7
    Join Date
    Apr 2020
    Location
    Prince George Canada
    Posts
    328

    Default

    Replaced my impeller and still have issues. Still overheating at low rpm. Cools fine above 2K. Replacing the impeller made no improvement. I’m leaning towards a faulty thermostat, anyone replaced this on a Raptor 400, and what is the difficulty rating for this repair?
    2020 Moomba Mojo
    2008 Mastercraft Prostar 197 40th Anniversary
    Owner Ness Lake Watersports
    Wakemakers “Exact Fit” Bags + Lead = 4,700 ballast
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  8. #8
    Join Date
    Jan 2021
    Location
    Columbus, Ohio
    Posts
    1,361

    Default

    It is as simple as you think. Pop the engine plastic cover off and the housing is right there in plain sight. 2 bolts and you are done.

    There is a coolant drain somewhere also so you don't make a mess. However, don't you still have warranty...sound like a dealer problem. How backed up are they?
    2015 Moomba Mojo Surf Edition
    4,000lbs
    Manual Flow

  9. #9
    Join Date
    Apr 2020
    Location
    Prince George Canada
    Posts
    328

    Default

    9 hour drive from the nearest dealership unfortunately. They will probably go good for parts warranty, but it’s going to be up to me to diagnose and repair for the time being.
    2020 Moomba Mojo
    2008 Mastercraft Prostar 197 40th Anniversary
    Owner Ness Lake Watersports
    Wakemakers “Exact Fit” Bags + Lead = 4,700 ballast
    Audio by Wetsounds, MTX, JL Audio, Clarion
    15 X 13.00 ACME prop

  10. #10
    Join Date
    Jan 2021
    Location
    Columbus, Ohio
    Posts
    1,361

    Default

    If you get the boat to temp and grab the main 2" hose on the top of the engine headed to the heat exchanger canister it should be hard and have fluid in it. If the thermostat isn't working it will be super easy to squeeze and restrict flow further.

    Have you had any other issue or work done? Could be an air bubble in the system.
    2015 Moomba Mojo Surf Edition
    4,000lbs
    Manual Flow

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