Overheating alarm on SeaRay Sundeck 200

Discussion in 'Sport Boats' started by mpickard, Jul 12, 2017.

  1. mpickard

    mpickard New Member

    Aug 14, 2012
    East Coast
    2010 Sundeck
    Overheating alarm on SeaRay Sundeck 220

    I have 2010 SeaRay Sundeck 220 with a 5.0L MPI Engine. I keep going into an over temperature alarm when I am running 3,000 RPM and above. The alarm does not occur when operating under 3,000 RPM. Everything seems to check out fine. My water pressure is 16.4 psi, my H20 Pressure is 12.9 psi and my engine operating temperature never get above 165 degree's. It normally is between 156-160 degree's when it goes into over temperature alarm and puts the boat into "limp" or "safety" mode. Returning to throttle to neutral for only a few seconds clears the alarm. I can then operate the boat in a non alarm condition until I hit 3,000 RPM's or above and then I get the over temperature alarm typically in less than a minute. All of the engines components are original. Water pump impeller has been replaced 2xs. Bought is serviced by the book every year. Had it to a certified Mercruiser repair facility and they found nothing wrong. Probably because they did not do what I told them to do...operate the boat over 3,000 RPM's and wait for the alarm. Heading on vacation on 7/21 and want to get my boat running. I am mechanically inclined and can pretty much do anything. Just need help trouble shooting this problem. Temperature sensor? I say no because my operating temperature is in normal range. Exhaust manifolds and risers? Maybe...they are 7 years old but my pressures seem normal....lost.
    Last edited: Jul 12, 2017
  2. skibum

    skibum Well-Known Member

    Jul 30, 2007
    Perry Hall, MD
    2005 Sundancer 260
    496 Magnum HO
    Does your boat have a Bravo III outdrive? If so, I'll bet you a nickel you are at the early stages of bravoitis. It's fairly easy to check. Follow the water inlet hose from the inlet of your seawater pump to the transom plate of the outdrive. It connects to a water inlet housing with 2 bolts holding it to the transom plate. The water hose should have a quick connector with a wire clip holding it in place. Use a regular screwdriver under the clip and give it a twist to pop the clip out about 1/4". You should be able to pull the hose off of it. Remove the 2 bolts, and take a look under it where the rubber hose comes through. If you've got it, you'll see if right away.

    Check out this thread: http://clubsearay.com/showthread.ph...o-Smartcraft-output/page3?highlight=bravoitis

    Post #58 Has a picture and #59 has a cell phone video.

    At 3,000 RPM and below the pump is able to supply enough volume of water to cool your engine. Above 3,000 RPM, the water pump can't get enough water so the impeller starts to cavitate. It makes air bubbles, which get to the sensor and that sets off the alarm.
  3. mpickard

    mpickard New Member

    Aug 14, 2012
    East Coast
    2010 Sundeck
    Re: Overheating alarm on SeaRay Sundeck 220

    Good call Skibum. I did have bravoitis this past year. Very low water psi at higher rpm's. I had it fixed. It wasn't easy. They literally had to pull my entire engine out to get to the area. Was just too tight. There is an upgrade kit that apparently helps prevent this from occurring again. When I had bravotis the alarm was "Low Water Pressure" not "Over Temperature Engine" like I am experiencing now. I have really good psi readings at high rpm's. water pressure is at 16 psi and H20 pressure is 14. Don't know the difference between the 2 but my gauges read both. In talking to a mechanic at Marine Max in Baltimore he said he thinks my pressures are too high which could mean some type of an exhaust restriction somewhere. He said it sounds like I am bringing plenty of water in but maybe not exhausting enough which could cause higher than normal pressures. I have a premium Mercruiser repair facility putting a computer on it this morning to see if we can't narrow down the problem to a more specific area. Thanks for the feedback. That was an excellent thought but I have already been there and done that.
  4. venetosr

    venetosr New Member

    Jun 14, 2018
    2003 searay sd22
    6.2 mercruiser
    I have a 2003 sundeck 220. 6.2 mercruiser. replaced the raw water pump impeller and thermostat. still overheats. replaced the manifolds and risers. still overheats. replaced engine circulating pump. still overheats. the new pump was noisey so I replaced it again. still overheats. took out the thermostat. still overheats. the water inlet holes in the lower unit are clear. any ideas??? help!!!
  5. Espos4

    Espos4 Active Member

    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    You mentioned lots of parts replaced, but no mention of the raw water inlet through the transom.

    That would be the next thing to check. It is very difficult to access on some boats.
  6. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Most systems have 2 sensors for the water temp. 1 for the gauge and 1 for the ECM.
    Have you checked it with an IR gun ? 16 psi at speed is normal.
  7. Happy Dayz

    Happy Dayz Active Member

    Jun 26, 2017
    Sarasota, FL
    '06 260 Sundancer, 6.2, BIII, Kohler 5kw
    79' classic Kona Family Cruiser jet boat..
    6.2 w/ BIII, 502 w/ Berkekley
    i have a 6.2.. did the same.. found a piece of broken imellar wedged in the fuel cooler exchanger after the raw pump for original owner servicing..didnt go look for the broken piece i guess... runs great now..
  8. searay205

    searay205 Member

    Nov 27, 2016
    2011 Searay sport
    5.0MPI Catalyst

    Excellent advice. Hook a Rinda and determine what the PCM is seeing. Yes 16 psi is normal!!!!
  9. aerobat77

    aerobat77 Member

    Aug 12, 2014
    2006 240 DA Sundancer
    5.0 MPI / Bravo III
    what is normal ? i have about 3 psi waterpressure at my 5.0 mpi and a buddy with the same engine has the same reading without any alarm or overheating . ( bravo 3 drive )

    16 psi sounds like you have a restriction after the sensor and the engine struggels to freely pump the water out again , so little circulation of water thru the block and instead buildup of backpressure .
  10. searay205

    searay205 Member

    Nov 27, 2016
    2011 Searay sport
    5.0MPI Catalyst
    at idle 1.5 to 3.0 psig is normal. At 3K rpm above anything between 10-18 psig. My dash gauge shows 175F while my Rinda shows 158F. My buddies Rinker showed 180F on dash and his PCM saw 160F. Dash gauges are useless. Boat has 160F thermostat. Thermostats fully open at their temperature setting but don't fully close until about 5-10F below their set temperature.
  11. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor

    Apr 21, 2009
    You've replaced a LOT of parts, but what diagnosis did you do to warrant that replacement? Do you get an alarm, does the gauge read high, or both? When it was overheating, did you feel the top of the elbows with your hand? Was there ANY scoring in the impeller housing? Did you do the impeller water flow test? Are you salt or fresh? You likely have a B3 drive (but confirm) so bravoitis is a possiblity. Hindsight, of course, is 20/20, but it would be well worth the hour of labor to have a pro look at it with a scanner. All of these things I've mentioned (and others) can be explained in more detail, but please do a search for them as they have been discussed many times. It will save us the time of replying over and over and over.
    Last edited: Jun 19, 2018

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