What temperature does your boat motor run at?

Discussion in 'Sport Boats' started by MacPhly, May 8, 2007.

  1. MacPhly

    MacPhly New Member

    Apr 28, 2007
    Saco, Maine
    2006 195 sport
    4.3 mpi
    I took my boat out today for the first time this season. I had the outdrive replaced under warrantee over the winter layup and was watching everything very carefully while putting her through some "sea trials".

    The one thing that I did not like was the engine temp. It seemed to be running hotter than last season and there were some 30 degree temp swings. Swings were from 170 to 200. Temp over all was averaging 180-185 instead of the solid 170-175 I saw last year.

    Keep in mind this is spring lake water in Maine... ie: make-your-feet-ache cold. Maybe the cold water is the difference. At summer lake water temps would you expect the thermostat to be full open? So with colder lake temps is the thermostat working and I have just never seen it before?

    What do you think?
  2. searay sport

    searay sport New Member

    Feb 21, 2007
    Ozark Missouri
    Mine runs at 185ish, and I was told the gueage may be a little off. They said if I was unsure to take an actual reading from the engine myself.
  3. 250_money_pit

    250_money_pit New Member

    I've got a 5.0 MPI and my thermostat kicks in at 160 degrees. When I am haulin' butt it stays between 162 to 165. I wonder how accurate the temperature sensors are though ?
  4. Presentation

    Presentation Well-Known Member TECHNICAL Contributor

    Oct 3, 2006
    Wisconsin - Winnebago Pool chain of lakes
    280 Sundancer, Westerbeke MPV generator
    twin 5.0's w/BIII drives
    Once warmed up mine stays just below 170.

    With your description I would be concerned about a impeller issue.
  5. MacPhly

    MacPhly New Member

    Apr 28, 2007
    Saco, Maine
    2006 195 sport
    4.3 mpi
    Thats what I was worried about but the outdrive is brand spanking new... Not a rebuild according to the dealer who replaced it. I would hope that means that the impeller is OK, but I guess anything is possible.

    Anyway, I just called the dealer and they will be looking at it soon.

    STIHLBOLTS New Member TECHNICAL Contributor PLATINUM Sponsor

    Oct 3, 2006
    Panama City Beach Fl/ South Ga
    2004 - 220 Sundeck
    5.0L w/Bravo 3 Drive
    Very unusual for temp swings that far apart unless something is wrong with the impellor or maybe the water pump. Might be that a hose was left off? Any water in the bilge? Did you get any high temp alarms?

  7. MacPhly

    MacPhly New Member

    Apr 28, 2007
    Saco, Maine
    2006 195 sport
    4.3 mpi
    No water in the bildge and no alarms.

    I was looking over the Stem to Stern website and the parts breakdown of the thermostat assemby. The thermostat itself says 160 degrees....!?! If the thermostat is supposed to start working at 160 something is definately wrong. I know there is water getting to the engine because the fronts (inlets) of exhaust manifolds jackets were cool. I don't have a good handle on the water flow sequence through the motor but if I'm getting water that far I'm betting on a bad thermostat. I'll have to wait to see what the dealer says.
  8. I am running both around 165 very consistantly.
  9. brimanst

    brimanst New Member

    Dec 20, 2006
    Mt. Pleasant, SC
    1998 Sedan Bridge 480DB
    Twin CAT 3196's 660HP
    two things come to mind, either a faulty guage or air in your cooling system. I had a guage oscillate because of a bad ground as well. It should run right at 170+-.

  10. ruf1967

    ruf1967 New Member

    Nov 18, 2006
    North Texas
    185 Sport
    Mine's at 170 when warmed up.
  11. midway

    midway Active Member SILVER Sponsor

    Oct 3, 2006
    Midway, Ga
    04 SeaRay 185Sport, Smart Tabs, Mageln Meridian Gold GPS, Hbird Matrix 87 dept/ff/gps/cp, Uniden vhf
    4.3L 190HP, Alpha 1 1.81 ratio, 14 1/4X21 Turning Point Prop
    Mine runs at 170 normal.
  12. GJarrett

    GJarrett Member

    Oct 3, 2006
    South Carolina
    '99 240 Sundancer
    5.0 MPI
    Your temperature swings precisely match the exact same symptoms in my auto when my thermostat starts going bad. I'd throw a new thermostat in before spending all that money paying labor hours to someone else. It won't cost you much of anything.... you can install it yourself easily, take the boat out for a quick spin, and if it still has the same symptoms you're only out a new tstat (which it never hurts to have anyway) but it may fix it and in that case you will have saved a whole lotta money. There's nothing at all to lose by trying.
  13. jhild

    jhild New Member

    Nov 2, 2006
    Cape Ann, MA
    1999 BW 18 Ventura /
    Sold: 2003 176BR
    Current: 135 OptiMax /
    Sold: 3.0L Alpha
    170 degrees on the button.

    I was thinking the same thing as Gerald: Bad t-stat.
  14. ehaze

    ehaze New Member

    Mar 16, 2007
    270 SLX 2007
    496 Mag w/Bravo III
    after reading this thread i paid more attention to the the temp tonight.

    never did it get over 161 even when i was cruising at WOT. most of the time it was in the mid 150's

    2006 220 select, 350 mag, about 35 hours on the boat
  15. GJarrett

    GJarrett Member

    Oct 3, 2006
    South Carolina
    '99 240 Sundancer
    5.0 MPI
    There are two common tstats - 140 degree and 160 degree. If you're running normal you should see temps about 10 degrees above the tstat. You might have a 140 degree tstat in yours.
  16. Gunn

    Gunn Active Member TECHNICAL Contributor

    Oct 4, 2006
    Potomac River - MD
    2003 280DA and 1995 Sea Ray 175
    Twin 4.3l and 3.0l, all w/ AlphaI GenII drives
    My 3.0l has a 142deg. thermostat in it. I wonder why it is so low? The hotter the engine is, the more efficient it is (why most autos today run 195-205)...to a point obviously. I wonder if I can go to a 160 aftermarket thermostat (if one is available), safely? I can't think of any reason why not....or why they picked 142 in the first place.
  17. MacPhly

    MacPhly New Member

    Apr 28, 2007
    Saco, Maine
    2006 195 sport
    4.3 mpi
    I spoke to my dealer yesterday and was told that my boat (4.3 MPI)should run at 170-175. They said it is possible that the raw water intake might have picked up something which would increase temp. Also said that early in the season the t-stat might be sticking a little. Anything over 200 is BAD, BAD, BAD! He also said that on this engine running the engine hard before it is warmed up (under 140 degrees) does as much damage as running it at too high a temp. So make sure your motor is warm before dropping the hammer.

    They suggested giving it another try and if I was still concerned they would recommend taking it in to have is looked at. I might take it out tomorrow to see if the results are any different than my first try.
  18. RT 240SD

    RT 240SD New Member

    Jun 16, 2005
    2000 240SD
    5.0 BIII
    5.0 here that runs a tick over 170 religiously once warmed up.
  19. Searay Jim

    Searay Jim New Member

    Oct 3, 2006
    240 Sundeck
    540cid w/BIII
    Thats good advise for any motor. It also highlights the importance of using the right oil. The oil needs to get some temp to it before running hard. Some engines may be less affected, but as a rule of thumb, unlike cars that can heat up the coolant quickly and maintain the temp, boat motors are being cooled by water thats constant and cool and take longer to bring oil temp up.
  20. Larry&Leisa

    Larry&Leisa Active Member

    Oct 26, 2006
    Keystone Lake Oklahoma
    1999 330EC
    sighhhh.... guess it's good there has been too much debris to float lately. Im still waiting to get my t-stat checked out for cold running engine. ( and glad I never really 'opened' her up before)

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