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Overheating Issue

Discussion in 'Ocean Yacht' started by Boomer, Jun 2, 2018.

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  1. Boomer

    Boomer Member

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    Brought the boat back from Charleston to St. Pete last monrh...no issues...yesterday the stbd. Motor is starting to overheat at speed...under 1200 rpm and it cools right down...motor was descaled and new impellers installed last month..plenty of coolant...water flow out exhaust looks same as other motor...suggestioms where to start? 1983 671 Detroit's tib
  2. Capt Ralph

    Capt Ralph Senior Member

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    How is your coolant level? Coolant still clean?
    How do you know it's over heating?
  3. Boomer

    Boomer Member

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    Coolant a tad dark but nothing excessive
  4. Boomer

    Boomer Member

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    She also blew off a turbo hose if that makes a difference
  5. Capt Ralph

    Capt Ralph Senior Member

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    Do you have a coolant recovery bottle?
    This is a 6-71TIB, rite?
  6. Boomer

    Boomer Member

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    Yes on both questions
  7. Capt Ralph

    Capt Ralph Senior Member

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    Next time you run, see if bubbles are coming up thru your coolant recovery bottle.

    Is it still your e gauge that states your getting hot?
    With I R gun, what is real temp middle of expansion tank?
  8. Boomer

    Boomer Member

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    Will find out on ride home tomorrow..the temp is definitely creeping higher...motir steams more than other one
  9. Capt Ralph

    Capt Ralph Senior Member

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    Where is home? Close?
    I'm concerned it may be a leaking injector tube. Combustion gases leaking into the cooling system.
  10. justold

    justold Member

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    Do you have the correct coolant mix ? Is the coolant greater than 50/50 ? If so you will more than likely run warm .
  11. Boomer

    Boomer Member

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    Home is couple hours away...coolant is the 50 50 straight from the bottle...jave an oil analysis pending outcome at detroit
  12. Boomer

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    No bubbling in overflow tank...1750 it holds fibe...over that the temp creeps up..put the or gun on it and it said 195 but a lot of steam...giod water flow out exhaust but definite black smoke also...not crop dusting black but noticable. Think i broke some stuff loose inside the motor and it is clogging up the heat exchangers?
  13. Capt J

    Capt J Senior Member

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    Check the smaller coolers. I had an issue like this and it ended up being zincs in the fuel cooler, which was directly after the raw water pump. Those are easy to pull hoses off of and shine a flash light through.
  14. Boomer

    Boomer Member

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    Drain the coolant out of the motor and disassemble? Thanks for the idea...haul out next weekend first then attacking the motor
  15. Capt Ralph

    Capt Ralph Senior Member

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    No, raw water sides. Clutch and fuel coolers. Maybe even the dump can mixer. Any where old zincs and debris can collect and restrict water flow.
    I now remember a problem I had 15 years ago and will return to again soon. The dump can mixers on out Berts 12V71 were full of old zincs and debris.

    Still watch that coolant getting darker. Learned a good lesson last year on one customers boat and an other customer going thru it again now, leaking injector tubes.
    Some old school shops may still have test strips that detect expanded gases in the coolant. Get some of these.
  16. Boomer

    Boomer Member

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    Can you please expand on leaking injector tubes...dump can mixer?
  17. Capt Ralph

    Capt Ralph Senior Member

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    Dump can mixer;
    Where the raw water after the engine HE, fuel cooler, clutch cooler connects with the exhaust system to cool the hot expanding exhaust gases.
    Usually a series of holes in the dump can (riser) pouring the used raw water into the exhaust.
    That first rubber exhaust hose connects to this dump can.

    Injector tube.
    Not complicated, just hard for me to explain but I'll try.
    Think of it as a copper sock that is installed in the cylinder head, thru the closed water system.
    It is flared and crimped to make it's ends seal in the head. The fuel injector is installed snugly in this sock (injector tube).
    The engine coolant helps keep the injector temp constant helping it match the performance of all the other injectors and keep the injector cool also.

    The tip and crimp of this sock on the cylinder end does take some abuse.
    After some injector changes and / or improper or inconsistent torquing of the injector retainer may cause it to leak.
    It usually shows it's symptom at speed when cylinder pressures start really getting up there.
    This problem luvs to show up in TAs and TIBs because of the added cylinder pressures at speed.

    Now you have a small amount of air in the system. All cooling designs do not allow air in the system. Some items may get hot.
    First easy detect is a small stream of bubbles in the recovery bottle. Next symptom is dirty coolant.

    I hope I explained that well, Anybody else is welcome to give it a try.
  18. Boomer

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    Actually made sense...thank you
  19. Capt Ralph

    Capt Ralph Senior Member

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    I'm in for kidney surgery tomorrow noon. Their going fishing for some stones,, again..
    I'm pretty hosed up on Vicodin now. Only took me 30 minutes to type that. Glad it helped.
  20. Boomer

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    God bless and well wishes your way for tomorrow

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