Starboard motor over heating at idle

Discussion in 'General Maintenance/Repair Questions' started by Ray Hannaman, Mar 12, 2019.

  1. Ray Hannaman

    Ray Hannaman New Member

    11
    Mar 12, 2019
    1989 Sea ray Sundance 300 DA
    Twin 350 mercruisers
    i have a 1989 Sea Ray Sundancer 300 Da with Twin Mercruiser 350 motors. Last season I bought this boat. Has about 1500 hrs, now has about 1600 hours on each motor. Ran fine when I first put it on the water. Then all of a sudden the starboard motor started overheating at idle In the spring time, I’m here in Portland OR , Columbia River area. I had this issue in the spring when there was dibre in the water. I took the boat and ran it all day. The problem then suddenly stopped. I ran it all summer and fall with no issues. Now the exact same issue is happening on the same exact motor. I have it on the water, what can I do to diagnose the problem? I just had this boat serviced, maybe I sucked up something into the system? Would it be the thermostat? I’m not even sure we’re to start? I see threads here staying it could be a hose or a spring. Any suggestions?
     
  2. Loyd Dinneen

    Loyd Dinneen Member

    304
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    If you haven't replaced the waterpump in the outdrive in awhile(should replace almost every year when the outdrive is serviced) I would start there and then move on to the thermastat. You could have a chunk of the waterpump impeller floating around the cooling system causing issues. Another thing to look at is your exhaust risers and see hot they are getting. This is very important since if the riser fails it will cause your engine to injest water and hydralock and that will kill your engine. The risers are replaced about every three years or so depending on whether you run in saltwater or not. I would also check your heatexchangers for injested garbage and clogs. All these things depend on whether your boat has this equipment. I had a starboard engine over heating and I flushed the closed cooling system,changed the thermastat , cleaned the heatexchanger, refilled the cooling system with 55% coolant, and replaced the riser and shutter. I have yet to put it in the water but on muffs it runs alot cooler than before.
     
    Last edited: Mar 13, 2019
    Ray Hannaman likes this.
  3. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    Since it's always happening at idle, I would start with easy things as it's 'unlikely' to be manifolds and such. Yes, check for debris - advice may depend on whether you have outdrives or not (your signature doesn't mention it). If your t-stat housing has that 'spring' you are referring to, then yes, that is a good place to start and you can do what those threads you found advise (stretch spring).
     
    Ray Hannaman likes this.
  4. Siboatguy

    Siboatguy Active Member

    290
    Mar 28, 2016
    Holmdel,NJ
    2005 Sea Ray 320 Sundancer
    Twins V-Drives
    2017 5.7 Mercruisers
    I would def say water pump first as it sounds like is losing its prime... And while your doing repairs it wouldn't hurt to though in a new thermostat in it....And i would do the housing and everything for the water pump not just the Impeller...
     
    Ray Hannaman likes this.
  5. JimG

    JimG Well-Known Member SILVER Sponsor

    Nov 4, 2008
    Southern WV
    2007 310 DA
    Kohler 5ECD
    Twin 350 Mags
    Raw Water Cooled
    V-Drives
  6. Ray Hannaman

    Ray Hannaman New Member

    11
    Mar 12, 2019
    1989 Sea ray Sundance 300 DA
    Twin 350 mercruisers
     
  7. Ray Hannaman

    Ray Hannaman New Member

    11
    Mar 12, 2019
    1989 Sea ray Sundance 300 DA
    Twin 350 mercruisers
    Thank you for these suggestions. So basically I need to pull it out of the water to have these services performed. Ughhhh. I JSU spend 4500.00 dollars servicing the engines, outdrives, generator, and fixing jelcoat. That sucks, salmon season is just now starting.
     
  8. Siboatguy

    Siboatguy Active Member

    290
    Mar 28, 2016
    Holmdel,NJ
    2005 Sea Ray 320 Sundancer
    Twins V-Drives
    2017 5.7 Mercruisers
    Well it depends if you have outdrives or not.... If you have V-drives or Inboards no u don't have to pull it out of the water....
     
  9. Espos4

    Espos4 Well-Known Member

    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    1st:
    Update your profile with more info. Sterndrives? Alphas or Bravos?
    Fresh water or raw water cooled?

    2nd:
    Give a detailed list of what was done in you’re recent $4,500 service.

    This will get you more accurate replies and quicker assistance in getting this sorted out.
     
  10. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    Even with an outdrive, you could actually still do an impeller change while in the water. The spring is even easier to be done in the water.
     
  11. Siboatguy

    Siboatguy Active Member

    290
    Mar 28, 2016
    Holmdel,NJ
    2005 Sea Ray 320 Sundancer
    Twins V-Drives
    2017 5.7 Mercruisers
    Unless his Impellers are in the outdrives... Witch does sound like they are....
     
  12. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    You know, given that the boat is an '89, you're probably right. Sure would help to know exactly what we're talking about...

    Although... it WOULD still be doable while in the water... just a bit on the awkward side... :)
     
    Ray Hannaman and Siboatguy like this.
  13. Soulshine

    Soulshine Active Member

    374
    Sep 25, 2016
    Seneca Lake, NY
    '83 SRV 360 Express
    Twin Merc. 454
    Curious here. How so unless it’s an OMC Cobra out drive?
     
  14. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    In shallow water. Or beach it - even get totally crazy and do it on logs with supports. Where there is a will, there is a way.
     
  15. Ray Hannaman

    Ray Hannaman New Member

    11
    Mar 12, 2019
    1989 Sea ray Sundance 300 DA
    Twin 350 mercruisers
    I’m not sure what outdrives they are, I’ll look in my owners manual to see if they are the Alpha or bravo. I looked at the circulation diagram, and it seems the water pump maybe The last mechanic who serviced the boat says the water pump is in the bildge. The risers on the motor were hot to the touch while the port side was very cool. In fact, one side was hotter than the other. I checked the strainers and they seemed very clean, the container is see thru and they did not look dirty at all. So if I need to have the water pump, tstat, and the risers Checked out and fixed, can that be done in the water, with a mobile mechanic dockside or would I have to pull it out?
     
  16. Ray Hannaman

    Ray Hannaman New Member

    11
    Mar 12, 2019
    1989 Sea ray Sundance 300 DA
    Twin 350 mercruisers


    I’m not sure if they are alpha or bravo, I’ll look at my owner manual tomorrow. I know it’s raw water cooled, and the risers in the port side were hot at 145-160degree on the gauge, while the port motor was nice an cool.
    I’m not sure if the outdrives have the water pump or if it’s in the bildge.

    The last service they changed out all the engine oils and outdrives oils. They put a thermostat in my generator, I had about 1300 in gel coat repairs from when my dockwheel came off and left a scrape. They winterized the fresh water system. And just did basic maintenance.
     
  17. Siboatguy

    Siboatguy Active Member

    290
    Mar 28, 2016
    Holmdel,NJ
    2005 Sea Ray 320 Sundancer
    Twins V-Drives
    2017 5.7 Mercruisers
    Well by you telling us that you have Sea Strainers,,, sounds like you have thur hull fittings with the Sea water pump on the front of the engine... I would replace them with the Stainless one's.... And yes you can do everything in the water..... As long as u can get your Sea cock to close on the intake.... or if they don't move and ur feeling brave stick a water bottle in the hose....
     
  18. Ray Hannaman

    Ray Hannaman New Member

    11
    Mar 12, 2019
    1989 Sea ray Sundance 300 DA
    Twin 350 mercruisers
     
  19. Ray Hannaman

    Ray Hannaman New Member

    11
    Mar 12, 2019
    1989 Sea ray Sundance 300 DA
    Twin 350 mercruisers
    Yes, there is a sea cock for both the generator and the engines
     
  20. tdschafer

    tdschafer Well-Known Member

    Aug 24, 2009
    Long island , NY
    1997 330 sundancer
    twin 454's, Carb, V-Drives
    Ray,
    That's half the battle. Now, do they operate? Many of these seem to freeze in position over time from lack of use.
     

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