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Overheating Issue

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

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  1. Capt J

    Capt J Senior Member

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    I just did a 3412, in dropped an entire intake valve seat. The boat sat a lot. Tore up the turbo pretty good, but the cylinder and piston were perfect. Sometimes you get lucky.....but usually not.

    I too would pull the other head and have it done......sitting does them no favors.
  2. Boomer

    Boomer Senior Member

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    Appreciate all the advise....wilm have the other head boroscoped..if issues seen, then rebuilt also
  3. Boomer

    Boomer Senior Member

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    Well...my overheat at speed problem has resurfaced...guld temp almost 90...thinking thermostat or heat exchanger...under 1500 and it cools back down...no bubbles in the overflow tank...fluid not pink but a little dirty...straight 50/50 coolent from Detroit...good water flow out the tailpipe
  4. chesapeake46

    chesapeake46 Senior Member

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    Detroits ?
    Original cast iron heat exchangers ?
    HP ?

    Mt friend's 692, 550 HP, cast irons units where ultra-sonically cleaned which solved his problem.
    I replaced mine with Lenco's . I have 671's - 410 hp
  5. cleanslate

    cleanslate Senior Member

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    You probably have sea skank in the tank! and else where...
    I use Barnacle Buster, two gallons and mix with two gallons of water and run that through my 471's let it soak for 6/8 hours. Hook back up the sea water hose and open up the sea cock and run the engine for a bit. Watch the junk come out of the exhaust when you first start it up. You'll be amazed. It cleans out the heat exchanger and all of the sea water system with in the engine.
    That cured my engine, running hot at 185/190 2000 rpm, now 175 at 2000 rpm.

    I'm sure stuff grows quickly in that warm Gulf water , which also grows in the engine. Unless you run 5/7 days a week, crap will grow/form with in.
  6. cleanslate

    cleanslate Senior Member

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    I thought Sen-dure was the only heat exchanger made for Detroits, J & T etc. ?
  7. Boomer

    Boomer Senior Member

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    Detroits 671 ti....original cast exchangers...the raw water side was descaled last year on both motors...if one heats up, wouldnt the other also?
  8. cleanslate

    cleanslate Senior Member

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    Not necessarily you generally have to treat each engine independently in my opinion .
    when you say cast the only thing that cast is the holding tank for the antifreeze and the heat exchanger ,the heat exchanger which is a rectangle shaped unit is bronze and has a bunch a little teeny tubes running through it and holes that’s the thing they can get clogged up easily even after one year with sea growth .
  9. Boomer

    Boomer Senior Member

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    Understood...look to drain the cast tank, disconnect inflow/outflow pipes, and the exchanger will be staring at you waiting for removal...then bring to a radiator shop to be boiled out
  10. cleanslate

    cleanslate Senior Member

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    You only have to remove one side, I think it’s the inlet side, anyway it’s the side with the flange on the Sun-dure heat exchanger, then slide it out with some effort ...
    It’s more than moving just the tubes, there are end caps etc that have to be moved also.
    Make sure you get new gaskets for the reinstall, don’t cheat with RTV crap. Also you will need to install a new big rubber o- ring that is in there too.
    I get it all from J&T Mt Laurel Nj.

    Anyway, I would still do the barnacle buster treatment first .
    There is other stuff out there on the market to buy a different name but it does the same thing .
  11. chesapeake46

    chesapeake46 Senior Member

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    In my case only the Port engine would run hot. Starboard ran right at temp.

    I can't answer that. All I can tell you id Lenco makes a HE for my engines. They make all kinds of HE's , oil, trans etc.
    Maybe Sen-dure made the cast ones ?
    The Lencos are not cast, more cooling capacity but do not last as long as the cast ones.
  12. cleanslate

    cleanslate Senior Member

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    I think I figured it out, mine are J and T cast tank, not the Cylinder tube type that both Lenco and Sen-dure make. I thought all Detroits had a big ass heavy cast tank on the front of them to which the heat exchanger was in. I believe J and T made there own tank to which the big bronze rectangle HE was used.
    I think we need Capt Ralph to chime in and unravel the mess I have created! Lol
  13. Capt Ralph

    Capt Ralph Senior Member

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    There must be dozens of different HSe on Detroit 2-strokes. Lil cast, large cast, round tube, square with round ends, dual round tubes and then the TA super coolers. Oil and/or clutch oil coolers on the block, in the HE or remote in the back of the block. Then air coolers.
    Detroit, J&T, Covington, S&S and many more thru the years.
    I gave up trying to remember that stuff long ago.
    Detroit serial numbers tell me who to call. Either My Detroit shop or a Western Branch shop.
    Don't feel bad if HEs confuse you, they still confuse the pros.
    Last edited: Aug 6, 2019
  14. Capt Ralph

    Capt Ralph Senior Member

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    Back to our latest symptom and my thoughts;
    If the inlet hoses were in your hands, I wish you replaced them. Been bit twice by inlet hose inner ply flapping in high demand water flow and restricting it.
    Been bit by restricted thru hull plumbing.
    Been bit by restricted remote oil coolers.
    I wish you could get that hose off the dump cans. Many times I have found zincs, scale, grey mud and rust restricting the water flow thru the mixer. If you are convinced all else is perfect, pull off the riser/can assembly and get it in your hands. I hope this is not the engine you had rebuilt. I hope the riser/can was gone thru VERY WELL on the engine that was rebuilt.
    Thermostats in Florida are not intermittent, all else is.
  15. Capt Ralph

    Capt Ralph Senior Member

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    Give me an idea of the fouling in your area.
    Grass? Shag rug? Slime? big or lil barnacles? Big green snot balls?
    In a canal where all the grass cuttings are tossed into the water?
  16. chesapeake46

    chesapeake46 Senior Member

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    I had an overheat problem many years ago that turned out to be the cast iron mixing elbows you call " dump cans " ? They were almost totally clogged w rust.
    Went through two pair over the years before getting stainless steel ones from DeAngelo.
  17. Boomer

    Boomer Senior Member

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    Dump can is clean...was cleaned last year when motor was apart...nothing in it either...stainless aftermarket by the way...water consists of silt, grass, and oysters...bottom cleaned several weeks ago....I am leaning g towards heat exchanger? I have the cast exchanger on the front of the engine..approx 1ft by 1ft
  18. cleanslate

    cleanslate Senior Member

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    Are the exhaust mixing elbows stainless steel and look new or are they the old cast-iron ones ?
    Just like Chesapeake 46 described .

    I replaced one of mine two years ago got it from J&T they only come stainless steel now no more cast-iron elbows are made .

    In my opinion stop guessing / over thinking and run some barnacle buster or whatever through the engine first and then go from there ....
    $60 a gallon jug.
    Get the engine warm first so all and any thermostats are opened up so you get that stuff throughout the engine and let her soak, see what happens .
  19. Boomer

    Boomer Senior Member

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    They are definitely stainless aftermarket...same on both engines...will warm the motor up, disconnect inlet and stick it in a 5 gallon bucket with the barnacle buster...when 5 gallons is gone, kill the motor and let it sit for several hours
  20. Capt Ralph

    Capt Ralph Senior Member

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    There was a nice write up (on another site) where the owner just drained his HE, drain plug back in, pulled the top zinc plug, plumbed up a funnel to this top zinc hole and poured in his own acid/water cleaner (stronger & cheaper) till full. Some time later put the plug back in, cleaned up the engine area and started the engine.

    Been meaning to do this my self, just have not got to it yet.