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  1. #1

    Default Volvo Penta TAMD71B Coolant Leak

    Our boat has a Volvo Penta TAMD71B. The other day, we checked the coolant level in the morning (normal level) and ran all day. The next day, I went to check the expansion tank and it was bone dry. The fluid was in the bilge. We filled the expansion tank back up, and ran the engine at idle and there were no leaks. The boat runs at 150 deg. when at idle cold and gets up to 180 deg. when operated (normally and now). At 180 deg. coolant starts rushing out of the expansion tank. Puts out about a gallon or more before stopping. Our mechanic said over the phone that it was the radiator cap. I replaced it this morning, and the same thing happens. He said that it was just pushing off excess coolant (overfill) and that everything is fine. Not sure why he didnīt say that yesterday.

    But, this doesnīt explain the original problem of the tank being bone dry.

    Anyone have some suggestions? Is a blown head gasket on the table?

    Thanks in advance for any feedback,

    Rip

  2. #2
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Volvo Penta TAMD71B Coolant Leak

    It could be leaking from any number of places. You are just going to have to watch the engine when it's under load and at max temp (and coolant pressure) to see where it's coming from.
    Don S.


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  3. #3
    Commander zbnutcase's Avatar
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    Default Re: Volvo Penta TAMD71B Coolant Leak

    Eyes are, even in this age of high tech, still the best inspection tool ever.
    You meet the nicest people at the American Legion.
    "maintenance is always cheaper than neglect"
    "certain parts are USCG approved for a REASON"
    "just because it's in the factory service manual, doesn't mean it's correct"

  4. #4

    Default Re: Volvo Penta TAMD71B Coolant Leak

    Thanks for your reply. I put clean oil diapers under the engine, and don't see any leaks when running. If there is a leak in the head gasket which is pushing coolant out the overflow tube, could I do more damage by continuing to run the engine?

  5. #5
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Volvo Penta TAMD71B Coolant Leak

    The only way to check to see if the head gasket is blown is to do a leakdown test on each cylinder to see if you have air escaping into the coolant. When you pressurize the cylinder, leave the heat exchanger cap off and see if bubbles appear in the tank. You could also have leaky injector sleeves in the head that could leak combustion air into the cooling system.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  6. #6

    Default Re: Volvo Penta TAMD71B Coolant Leak

    Thanks again for your help Don. I just took her out for a spin. I put papertowels down and watched with a flashlight while someone else drove. Never saw any leaks. However, new stuff is happening. Once the boat was under load at 1500 rpms, the coolant started purging itself out of the overfill tube again. It also started over heating for the first time. There was coolant still in the expansion tank afterwards, so it wasn't due to a lack of coolant. The temp got up to 200 before backing it down to idle. At idle it went back down to 180. There was plenty of air mixed with the coolant when purging out the overflow tube. ALSO, there is now blue-gray smoke from the exhaust. Not much, but enough.

    I am assuming it's a blown head gasket. I saw before that I need to do a look down pressure test to make 100% sure.

    My question is... if this is a blown head gasket, what caused it? Could there still be another issue that caused the engine to overheat at some point and ruined the gasket? If it was a bad gasket (engine was rebuilt 2 years ago) or not torqed properly, would the leak surface in a day or would it usually start slow and get worse and worse?

    Thanks again,


  7. #7

    Default Re: Volvo Penta TAMD71B Coolant Leak

    Also, how do I test the injector sleeve?

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