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  1. #1
    Join Date
    Jan 2020
    Location
    San Diego, CA
    Posts
    2

    Default Guardian Alarm at 3K RPM, Exhaust Steam, Possible Overheat

    We are looking for opinions and feedback fromknowledgeable marine gas engine mechanics, etc.

    We have a 2002 Bayliner with two Mercruiser 350 MAG MPI Horizons gas inboards. We have only owned the boat for 8 months, and have very little knowledge of the engine maintenance, other than the port side block has been replaced 09/2018 and the starboard side block replaced 07/2017. (Blocks replaced due to water backwash.) We understand that there are less than 30 hours on both blocks. This is what we know:

    PORT SIDE

    • Block replaced 09/2018 (25 HOURS)
    • Exhaust manifold. riser, elbows replaced 09/2018
    • All other components such as heat exchanger is original 2002 equipment (we have not proof or verification of any replacement or servicing)
    • Steam from exhaust
    • Engine running temp 175-178 degrees
    • IR Temp at exhaust elbows: 95-98 degrees


    STARBOARD SIDE

    • Block replaced 07/2017 (35 HOURS)
    • Unknown condition of exhaust manifold, or if/when replaced at time of last block replacement
    • All other components such as heat exchanger is original 2002 equipment (we have not proof or verification of any replacement or servicing)
    • Mass steam from exhaust
    • POSSIBLE side causing Guardian Alarm at 3K RPM
    • Engine running temp at 178 degrees
    • IR Temp at exhaust elbow: 98 and 101 degrees



    We have replaced the impellers, the metal housings looked okay with no grooves.

    We get a guardian alarm at 3,000 RPM, with temps approaching 180 degrees.

    There is an abundance (vast amounts) of steam from both exhausts, more on the starboard side.

    OUR PLAN

    • Remove and service, or replace heat exchangers.We believe the zincs in the heat exchangers may not have been replaced inseveral years.
    • Service or replace Oil Coolers and TransmissionCoolers
    • Disassemble and examine Starboard exhaustmanifold
    • Install 6" risers on both engines forbetter exhaust hose slope
    • Install inline exhaust flappers (Corsa flappers)


    ANY THOUGHTS OR INPUT???

    Your feedback is welcomed, as we are novices atthis.



  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    8,018

    Default Re: Guardian Alarm at 3K RPM, Exhaust Steam, Possible Overheat

    Why not get both engine ECUs scanned before through a small fortune of new parts into it?

    For less than one heat exchanger costs new, you could get a pretty capable system from RINDA....

  3. #3
    Join Date
    Jan 2020
    Location
    San Diego, CA
    Posts
    2

    Default Re: Guardian Alarm at 3K RPM, Exhaust Steam, Possible Overheat

    Thanks for the feedback. We had a Mercruiser mechanic scan ECMs, and he made a suggestion that included items/plan above. However, he wasn’t definitive in his assessment of the problem; thus the inquiry of a second opinion here.

  4. #4
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    8,018

    Default Re: Guardian Alarm at 3K RPM, Exhaust Steam, Possible Overheat

    Why not share what the ECM scans revealed?

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