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High Exhaust Alert

Discussion in 'Technical Discussion' started by gr8trn, Apr 1, 2018.

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  1. gr8trn, Apr 1, 2018
    #1
    gr8trn

    gr8trn Senior Member

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    Happy Easter! A few questions.

    I mistakenly ran my stbd engine with raw water closed. After idling for a few minutes I pulled out and ran at low rpm under 1000 for about 5-8 minutes before getting a High Exhaust Temp alarm on VesselView stbd engine. I cut back to idle and realized I have screwed up my start up routine and failed to open the raw water on the stbd engine. I opened it immediately. Engine temp was showing 172 on the VesselView. I X´ed out the High Exhaust Temp alarm and powered back up to 800 to 900 RPM. The alarm sounded again in a few minutes so I slow idled back to the marina. The engine did not go into safe mode.

    Raw water pump inspected, impeller changed just to be safe as I ran it dry.

    Today on start up, yes I had raw water open this time, I got the High Exhaust Alarm again. On the VV it is showing in the alarm history and the active alarms.

    If I disconnect the wire harness at the exhaust sensor, the alarm still shows Active. I unplugged the VV as well and the alarms persist.

    I have not been able to clear the History or the Active alarm.

    My inspection of the exhaust reveals no external damage.

    Is this high temp sensor a one time and replace type of thing?

    Have I damaged the exhaust system?

    Thanks for your input.
    Last edited by a moderator: Apr 1, 2018
  2. MBevins, Apr 1, 2018
    #2
    MBevins

    MBevins Senior Member

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    Have you confirmed raw water flow out the exhaust?
  3. gr8trn, Apr 1, 2018
    #3
    gr8trn

    gr8trn Senior Member

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    Yes, flow is intact at idle through the exhaust and at RPM through the Zeus Pod.
  4. MBevins, Apr 1, 2018
    #4
    MBevins

    MBevins Senior Member

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    Then using a multimeter, check the continuity of the sensor. You'll need to check the good side first to determine if it is normally open or normally closed.
    Then compare it to the alarmed side.
    If both the same you may have a software (or hard relay) latch that needs to be reset.
  5. gr8trn, Apr 1, 2018
    #5
    gr8trn

    gr8trn Senior Member

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    Thanks much.
    Do I simply unplug the sensor and put one lead on each side of the plug to do this?
  6. MBevins, Apr 1, 2018
    #6
    MBevins

    MBevins Senior Member

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    Yes, you should read pretty well zero ohms if it's N/C. If it's N/O then you will need to heat the sensor to confirm it functions. You can do this by putting it in boiling water or use a heat gun if you have one.
  7. Pascal, Apr 1, 2018
    #7
    Pascal

    Pascal Senior Member

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    Why do you close the sea cock anyway?

    Besides the alarm problem, you need to inspect the exhaust hoses. While they are high temp hoses, they can be damaged when ran dry
  8. 30West, Apr 1, 2018
    #8
    30West

    30West Member

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    Check you are getting flow on both sides of that engine if it has two exhaust manifolds. You should be able to hold your hand on each riser when the engine is up to temp, and they should be about the same temp. IR thermometer would be handy for this also.
  9. Jorge Lang, Apr 2, 2018
    #9
    Jorge Lang

    Jorge Lang Senior Member

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    You can always swap the temp sensors to see if the alarm goes to the other engine. Look for any discoloration in your fiberglass and on the blue hose.
  10. gr8trn, Apr 4, 2018
    #10
    gr8trn

    gr8trn Senior Member

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    To close a hole in the bottom of my boat I guess. Just sees prudent. I certainly found a flaw in my thinking, didn’t I?
  11. gr8trn, Apr 4, 2018
    #11
    gr8trn

    gr8trn Senior Member

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    Thanks. I was thinking an IR thermometer would be a good tool to add as well.
  12. gr8trn, Apr 4, 2018
    #12
    gr8trn

    gr8trn Senior Member

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    Thanks, glass looks equal to port exhaust and all hose looks and feels good.
  13. gr8trn, Apr 5, 2018
    #13
    gr8trn

    gr8trn Senior Member

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    I replaced the impeller and fresh water pump today as the cover plate was scored and the brass looked scored as well. Better safe and a simple enough job. I replaced the belt as well, it did have a bit more belt dust than port.

    New sensor on order.
  14. Capt Ralph, Apr 5, 2018
    #14
    Capt Ralph

    Capt Ralph Senior Member

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    How bad was the scoring? From normal wear or friction of a dry impeller.
    Some bad scores may shorten the new impellers life.
  15. gr8trn, Apr 5, 2018
    #15
    gr8trn

    gr8trn Senior Member

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    Not sure if it was wear or dry damage. I replaced the pump.
  16. Capt Ralph, Apr 5, 2018
    #16
    Capt Ralph

    Capt Ralph Senior Member

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    Best plan.

    Best Plan... Still assuming Cummins/Sherwood pump, Always better to replace these reef material projects.