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  1. #21

    Re: coolant in 12v71 oil

    Quote Originally Posted by kelpy View Post
    Which hose failed? It sounds like the head is cracked but that doesn't happen to 6R or 6L very often.The head may have failed first causing the hose to burst. You can check the remaining coolant in the HE with a test strip to see if exhaust residue is present.
    The 4” 90 degree hose here

  2. #22

    Re: coolant in 12v71 oil

    Hopefully you just melted the rubber seals . I didn’t get that lucky and cracked a head but the gauge was pegged when I caught it. I was letting a friend hold the wheel so I don’t know if I could have caught it in time either. It ended up being a steel tube that connected the he tank to the circulating pump. I hope the damage isn’t too severe. 180 shouldn’t have melted the seals.

  3. Re: coolant in 12v71 oil

    It’s amazing how quickly things go wrong once coolant leaks out. A couple years ago a guy I know with a 65 convertible lost a coolant hose and smoked a 12-92. It was toast before he system monitor caught it or perhaps his monitor wasn’t working. In any event a big deal. Hope all works out and isn’t too bad. Keep us informed and do post more pics!

  4. Re: coolant in 12v71 oil

    Quote Originally Posted by ageless View Post
    Discussing with the Mrs which direction to go, she’s been surprisingly accepting of repower, she insist on a new fridge and eliminating the raw water heads in return
    I would jump all over that!

    Those hoses looks like they should have been changed out years ago.

    The engine would have to be been smoking hot to degrade the seal rings. They are pretty stout. Either way, the head will have to come off.
    Last edited by kelpy; 05-18-2018 at 08:22 AM.

  5. #25

    Re: coolant in 12v71 oil

    Quote Originally Posted by kelpy View Post
    I would jump all over that!

    Those hoses looks like they should have been changed out years ago.

    The engine would have to be been smoking hot to degrade the seal rings. They are pretty stout. Either way, the head will have to come off.
    I think 215 degrees and up is what Detroit has claimed.
    Semper Siesta
    Robert Clarkson
    ASLAN, 1983 55C #343
    Charleston, SC

  6. #26

    Re: coolant in 12v71 oil

    My $.02 may or may not help, but this is what I experienced after bringing my (then) new boat home from NC to CT. 12-92's ran great with no issues. The morning after the last run into port, I checked the oil and found exactly the same in my port engine oil pan. Lots of probing, pressure testing ....... you name it. Without getting too long winded, I found that the coolant pump seal blew. The weep hole was clogged and the seal between the gear drive shaft and the timing case side of that pump blew as well. Result .... after the engine was shut down and there was residual pressure in the coolant system, coolant entered the crankcase via the timing cover under which is the pump gear drive. My guess it started with residual pressure and turned into a siphoning effect. I pumped out 4 gal of clean pink coolant before (luckily) getting to un-tainted engine oil. Changed out the coolant pump, oil, and coolant and all good. Are 12-71's and 12-92's similarly configured? That I do not know. But the similarities in your situation and what I experienced is evident. Hope you fare as well as I did.
    JJ.

  7. Re: coolant in 12v71 oil

    Quote Originally Posted by jjgar's54 View Post
    My $.02 may or may not help, but this is what I experienced after bringing my (then) new boat home from NC to CT. 12-92's ran great with no issues. The morning after the last run into port, I checked the oil and found exactly the same in my port engine oil pan. Lots of probing, pressure testing ....... you name it. Without getting too long winded, I found that the coolant pump seal blew. The weep hole was clogged and the seal between the gear drive shaft and the timing case side of that pump blew as well. Result .... after the engine was shut down and there was residual pressure in the coolant system, coolant entered the crankcase via the timing cover under which is the pump gear drive. My guess it started with residual pressure and turned into a siphoning effect. I pumped out 4 gal of clean pink coolant before (luckily) getting to un-tainted engine oil. Changed out the coolant pump, oil, and coolant and all good. Are 12-71's and 12-92's similarly configured? That I do not know. But the similarities in your situation and what I experienced is evident. Hope you fare as well as I did.
    JJ.
    Good advise. This could happen on a 12-71 as well as the pump is gear driven and is directly connected to the oil passageway. Its definitely worth checking.

  8. Re: coolant in 12v71 oil

    The drain pasasage is pretty large to get crudded up but evidently it can happen. Doesn't sound like it in this case though. The OP found evidense of coolant in cylinder 6R. It cant get there from the coolant circulating pump.

  9. #29

    Re: coolant in 12v71 oil

    The pins that the rockers pivot on in the cylinder head have coolant under them. If they become loose, that is a potential source of coolant in the oil.

    When I had coolant in my oil, it was not emulsified but concentrated in the bottom of the oil pan even though that coolant/oil had been circulated through the engine.

    I also experienced coolant in the oil from a couple of cracked liners on my 12V71TI.

    It's probably overhaul time. It was each time for me.

  10. #30

    Re: coolant in 12v71 oil

    We've had this a few times so a couple thoughts and they're only worth what you paid for em!

    1. 180 degrees shouldn't be too hot
    2. It's rare an oil cooler fails. Usually it will transfer oil in the coolant since oil pressure is higher than coolant pressure.
    3. JJgar's54 has a good thought on the water pump. It will make coolant temp rise and transfer water quickly. Had this happen last year.
    4. Injector tubes will cause water in oil, usually not quickly thought. Hopefully the pic will post of one we found last week.


    Pressurize the system and let us know what you find. Were always up for an education.
    If it wasn't so far I'd help you.



    871 water in oil.jpg
    1984 Hurley 36 Express sold
    1974 46C series I sold
    1984 46HP series II

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