overheating

Discussion in 'General Maintenance/Repair Questions' started by Km renovations, Jan 12, 2020.

  1. Km renovations

    Km renovations New Member

    16
    Jul 20, 2019
    2004 sea ray sundancer
    5.7 mercruiser 350 mag w/bravo3
    hello I recieved alot of help from this forum .

    currently I am trying to diagnose an overheating issue .
    at idel my temp climbs up to 200
    around 1200 rpm the temp is at normal opperating temp 165
    however anything over 1200 rpm and the engine will over heat again

    impeller was changed 6months ago on the raw water intake
    thermostat was installed . (when the boat was purchased there was no thermostat)
    I have removed the outdrive after reading the raw water intake hose will colapse on itself through corrosion . however the hose appers new with no blockage .
    my attempt now is to check hoses for debris,change thermostat again, and install anoth imperller while I am at it .

    any suggestions out there on what else I should consider?
    350 mag mercruiser with bravo 3 outdrive .
     
  2. Espos4

    Espos4 Well-Known Member

    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    The end of the water hose that collapses can’t be seen by removing the outdrive.

    you need to go inside the boat and remove the inlet from the inside of the transom. Then you can inspect the end of the water house for a restriction. This is also called “bravoitis”
     
  3. stephens013

    stephens013 Active Member

    446
    Oct 8, 2009
    Ft Walton Beach, Fl
    2001 510 Sundancer
    1997 400DA Sundancer
    1994 Chalarral 310 Signature
    3196 Cat; 660 PHP
    3116 Cat; 340 PHP
    Had a similar issue on port engine of my Signature 31 a few years back. Did much the same as you have done with no effect. Finally stared looking for the less obvious. Found a bolt lodged up in one of the passage ways of a riser. Had to bust it lose it was so titily wedged in. Anyway, double checked both sides for obstructions, slapped it back togeather and off we ran. Problem solved.
     
  4. Km renovations

    Km renovations New Member

    16
    Jul 20, 2019
    2004 sea ray sundancer
    5.7 mercruiser 350 mag w/bravo3
    I am open to trying this approach , however it is a very tight area . I will resume checking the hose tomorrow
     
  5. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    What model Sundancer?

    Where has the boat been used?

    Do you ever get an overheat alarm?

    When the gauge shows the temps getting hot, what do the top of the elbows feel like with your hand? You should be able to keep your hand on them.
     
    joeyleggz and Chris-380 like this.
  6. DWABoat

    DWABoat Well-Known Member

    612
    Aug 13, 2019
    S Louisiana
    2001 280 Sundancer
    1989 220CC Cuddy Cabin
    Twin 4.3 w/Alpha Ones
    5.7 Mercruiser Alpha One
    Is there a sleeve insert inside your thermostat housing? You mentioned you had to put one in.
    On my older 5.7L, it was running 180+ under a load, but 160 low speed.
    I discovered someone had installed the sleeve in the housing upside down and restricted the water flow. I flipped it over. Been 12 years and running at 165.
     
  7. Km renovations

    Km renovations New Member

    16
    Jul 20, 2019
    2004 sea ray sundancer
    5.7 mercruiser 350 mag w/bravo3

    boat has been used in Florida salt water, I have owned this boat since july 2019

    yes overheat alarm engages around 195degree

    I have not laid hands on the elbows
     
  8. Km renovations

    Km renovations New Member

    16
    Jul 20, 2019
    2004 sea ray sundancer
    5.7 mercruiser 350 mag w/bravo3

    there is an inserted plastic sleeve. I do belive it is positioned correctly . the boat has ran great for aprox. 5 months after my initial maintenance .
     
  9. Km renovations

    Km renovations New Member

    16
    Jul 20, 2019
    2004 sea ray sundancer
    5.7 mercruiser 350 mag w/bravo3
    I am fairly new to the boat, I have done some maintenance and checked cooling hoses but have not messed with the risers as of yet . I am going to troubleshoot a few more areas but I will keep this in mind
     
  10. Km renovations

    Km renovations New Member

    16
    Jul 20, 2019
    2004 sea ray sundancer
    5.7 mercruiser 350 mag w/bravo3
    I have at one point brought this boat into sho
    allow waters which lead me to getting stuck and possibly sucked up some sand . I did not have immediate issue from that but may possibly be experiencing them now?

    last oil change is when I started experiencing the over heating at idel and above 1200 rpm . however oil pressure is good and I put anout 5 quarts of oil in and kept the same oil filter
     
  11. DWABoat

    DWABoat Well-Known Member

    612
    Aug 13, 2019
    S Louisiana
    2001 280 Sundancer
    1989 220CC Cuddy Cabin
    Twin 4.3 w/Alpha Ones
    5.7 Mercruiser Alpha One
    I think you should pull those manifolds immediately, whether that is the cause of the overheating or not.
    Since you just got the boat, it has lived in salt water, and you don’t know how old the manifolds are, you need to evaluate.
    If the manifolds are severely rusted/corroded inside, they can still look clean on the outside. At some point, the insides can corrode and cause water leakage into your engine cylinders and blow your engine by hydro lock. I don’t know the year of your boat. You could have dry exhaust or wet. Either one can have corrosion on the mating surfaces.
    Since pulling them is simple and only costs the price of gaskets, it is a logical step in your evaluation and just good business.
    Also, pulling the manifolds gives easier access to the backside of the motor for the other work.
    Pull the manifolds/risers. Take lots of pictures from all angles. Post them here for these guys to take a look.
     
  12. Km renovations

    Km renovations New Member

    16
    Jul 20, 2019
    2004 sea ray sundancer
    5.7 mercruiser 350 mag w/bravo3
    Ok Thank you for simplifying this, previously I had assumed it was a large job to check the manifolds
     
  13. DWABoat

    DWABoat Well-Known Member

    612
    Aug 13, 2019
    S Louisiana
    2001 280 Sundancer
    1989 220CC Cuddy Cabin
    Twin 4.3 w/Alpha Ones
    5.7 Mercruiser Alpha One
    Nope. Done it many times by myself. Not even a helper.
    Just be sure to drain the manifolds first before loosening the first bolt.
    Lots of YouTube videos about removal.
    Should be done every few years as periodic maintenance.
     
  14. skunkman

    skunkman Member

    422
    May 27, 2014
    Longboat Key
    Looking for 330 Sundancer
    350 twins
    Why no thermostat to start with? Was this the previous owners solution to overheating? Remove the thermostat and see if it still overheats. Check the thermostat in hot water.
     
  15. Km renovations

    Km renovations New Member

    16
    Jul 20, 2019
    2004 sea ray sundancer
    5.7 mercruiser 350 mag w/bravo3
    I am not sure why the previous owner had no thermostat. I have to reinstall the outdrive before I can start it up and check the overheating
     
  16. Handsome Transom

    Handsome Transom Active Member GOLD Sponsor

    555
    Jan 26, 2018
    Penetanguishene Ontario Canada
    1989 SeaRay Sundancer 268 454 Bravo
    454 Mercruiser bravo drive
    Blockage in the exhaust would be my best guess pieces of an old impeller , pieces of shutter valves or both
     
  17. mbartlett!

    mbartlett! New Member

    5
    Feb 5, 2020
    1986 340 express cruiser, twin mercruiser 350.
    5.7 mercruisers direct drive
    Hello. Does anyone know the part number for a 1986 5.7 liter 260 hp sea pump impeller. Its in a 340 express cruiser with straight shaft drive. Thanks for the help.
     
  18. Korkie

    Korkie Active Member GOLD Sponsor

    768
    Feb 2, 2016
    Leonardtown, MD Potomac River / Chesapeake Bay
    340 Sundancer 2006, Garmin 7612, xHD Radome
    Merc 496 Mags
    Bravo III Drives
    KM renovations. What are your H2O pressure readings on your gauges. Lower readings @ high rpms indicate no preload (blockage before your pump)i.e. Bravoitis, inlet blocked. High readings indicate blockage after the pump (restriction) i.e. plugged up heat exchanger, manifolds, etc. When we got our 340 with 496mags, had to pull heat exchangers and clean them mid season / then 2 years later had bravoitis, then just did manifolds this past fall. Everything looked great until you got inside of things. Did exchangers due to water pressure pushing up into the high 30s @ 3500rpms, used Barnacle Buster and dropped temps and pressures down to normal. Then had low pressure on one motor, pressures at 7-10 @ 3500rpms, Bravoitis, as pump wasn't getting enough water. This past season - temps had been creeping up on one motor as we went through the summer. Knowing the heat exchangers were good, impellers were only a year old and I installed thru hulls with strainers and dc'd the outdrive supply - had to be the manifolds. Although the manifolds looked like new on the outside. But on the inside I was just one cruise away from disaster. Some of the inner walls were sooo thin I could poke my finger thru them and they were all plugged up with rust scales. Moral to the story - look at and RnR anything and everything if you are not sure of its condition.
     
  19. Km renovations

    Km renovations New Member

    16
    Jul 20, 2019
    2004 sea ray sundancer
    5.7 mercruiser 350 mag w/bravo3
    Hello, this virus has given me the at home time needed to continue my boat project.

    recent work;

    bravo 3 outdrive removed. Had a unknown flange fall out with 2 pieces of metal. I later found this was a peice of shutters from the exhaust.

    I removed the exhaust elbows and saw both sides....shutters gone. All that remained was the metal cross bar on each side.

    I could not find a way to check the exhaust system for remaining debris. Like I said, all I found was 2 peices of metal and one highly dry rotted peice of shutter.

    I changed them out. Checked the manifolds and installed new gaskets. Installed new thermostat and another new impeller.

    when I attached the muffs, I ran the engine for approximately 5-7minutes Until normal temp was reached at 165. At that point the Tim continued rising all the way to 195 and white smoke followed out of the exhaust.

    When I turn the boat off, the outdrive was hot to the touch and the exhaust manifolds were severely hot.


    Still looking to find the source of overheating. Could it be the debris in exhaust that would also cause the white smoke?


    I also witnessed a loud squealing sound from the belt. Did not seem normal. Middle water pump even seized a couple of times but continued to run.
     
  20. Korkie

    Korkie Active Member GOLD Sponsor

    768
    Feb 2, 2016
    Leonardtown, MD Potomac River / Chesapeake Bay
    340 Sundancer 2006, Garmin 7612, xHD Radome
    Merc 496 Mags
    Bravo III Drives
    When you started the motor do you get ample water flow out the outdrive? Make sure your muffs are tight and your motor is actually picking up the water. When I run mine on muffs I put a couple of bungee cords around the muffs to hold them nice and tight to the drive so there is only a little water coming out around the muffs. Unfortunately the white smoke may have been your new impeller burning up. So need to check and possibly replace that again. So far as the pulley you mentioned seized a couple of times, that certainly needs to be addressed.
     
    JVM225 likes this.

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