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  1. #1

    8V92 coolant loss

    One of my 8V92's is loosing coolant. No apparent leaks. No water in the oil (thank god!). Leaking into raw water in heat exchanger and out the exhaust? Has anyone had this issue or any ideas?

  2. #2

    Re: 8V92 coolant loss

    if no leaks, no water in oil the likely suspect imo is the heat exchanger. I'd pull it and have it cleaned and tested.
    SOUTHPAWS
    1986 52C Hull #391 8v92TI
    PENSACOLA, FL

  3. #3

    Re: 8V92 coolant loss

    Or it's finding its way past the sleeve seal(s) into the combustion chamber and going out the pipe not in the water but in the fumes?
    1978 53' Motor Yacht "LADY KAY V"
    Hull number 524
    Chesapeake Bay

  4. #4

    Re: 8V92 coolant loss

    Does the '92 series also suffer from injector tubes leaking AF into the oil? Over time small amounts get into the oil and boil out. It shows up in the oil analysis. A clean piston dome is an indication on a straight 6 like the 6-71.
    Regards
    Dan

  5. #5

    Re: 8V92 coolant loss

    I would suspect the heat exchanger as a first option, given the oil is clean. You should be able to test in place if you have a Radiator Pressure test kit, by isolating the heat exchanger raw water & coolant side. If it fails the test, you should be able to take to a good radiator shop to see if it is repairable.
    Best regards,
    --
    David

  6. #6

    Re: 8V92 coolant loss

    Quote Originally Posted by Dan Mapes View Post
    Does the '92 series also suffer from injector tubes leaking AF into the oil? Over time small amounts get into the oil and boil out. It shows up in the oil analysis. A clean piston dome is an indication on a straight 6 like the 6-71.
    Hopefully there is a coolant recovery bottle. If you see bubbles or overflow, Injector tubes are the #1 suspect.

  7. #7

    Re: 8V92 coolant loss

    Pull the hose on the air box drains and see if coolant runs out. If so, you can pull air box covers to see which cylinder is the culprit. If no coolant in the air box drains, I'd pull a raw water hose off the heat exchanger. Assuming you have the tank full with coolant, put something under the outlet and check for coolant after a short period. You may need to pressurize the cooling system with a tester, I wouldn't take it above 15 psi.

    We had 2 cracked liners caused by faulty liner o-ring seals. Kept losing coolant, as long as we ran it, it vaporized the coolant. Never made any oil until it sat for a couple weeks. Like stated above though, an oil analysis will find it if it's making it's way into the cylinders

    Hoping for the best for you...
    Randy

  8. #8

    Re: 8V92 coolant loss

    My injector tubes were leaking but never showed up in the oil anylisis vaporized and went out the exhaust. I pulled the air box covers and pressurized the system. I could see drips coming from the tubes
    "DON'T BELIEVE ANYTHING YOU READ OR HEAR AND ONLY HALF OF WHAT YOU SEE" - BEN FRANKLIN




    Endless Summer
    1967 50c 12/71n DDA 525hp
    ex Miss Betsy
    owners:
    Howard P. Miller 1967-1974
    Richard F Hull 1974-1976
    Robert J. & R.Scott Smith 1976-present

  9. Re: 8V92 coolant loss

    Similar issue in my STB main a few years ago. Boost Cooler.......was blowing it out the exhaust.....

  10. #10

    Re: 8V92 coolant loss

    Quote Originally Posted by rsmith View Post
    My injector tubes were leaking but never showed up in the oil anylisis vaporized and went out the exhaust. I pulled the air box covers and pressurized the system. I could see drips coming from the tubes
    Would a symptom of that also be super clean pistons?
    SOUTHPAWS
    1986 52C Hull #391 8v92TI
    PENSACOLA, FL

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