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Oil in Coolant..Volvo Tamd74 EDC

Discussion in 'Engines' started by Prospective, Sep 21, 2020.

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  1. Prospective

    Prospective Senior Member

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    When it rains it pours...

    Many of you have chimed in on my thread where I think I dodged a bullet on a transmission issue. Then another thread where I broke an exhaust elbow. Well, I got both elbows replaced along with the ancillary things that needed to be done and went to pick up the boat this weekend.

    Previously I noticed I had been losing a little bit of coolant on my port engine (elbow issue was starboard). Expansion tank was empty and I've probably put a quart of coolant in since a cooling system rydlyme flush/refill at the end of last seasons (maybe 40hrs ago).

    So I was checking things over and popped the coolant cap on top of the engine to check the level there since expansion tank was empty. I found it covered in oil. I dipped my finger in and got to coolant pretty quick. So estimating 2-3 ounces of oil that settled at top.

    Needless to say I left the boat at the yard and advised them of the issue. Hopefully they're looking at it today. But I like to get my ducks in a row.

    As I understand it oil in coolant could be one of 3 things... head gasket, cracked head, or oil cooler.

    I change my own oil at the end of each season and have never noticed anything odd about the used oil. But I pump it into buckets and don't always see it that closely. The yard JUST changed the oil as part of this exhaust elbow service and didn't say anything about the oil looking odd but not sure how carefully they looked either. And I'm not losing much coolant so not sure how noticeable it would be in the oil (7+ gallons). I would also note I've never had a problem with temps.

    My best guess is and I am hoping it's the oil cooler, as I think that would be cheaper to replace than tearing down the top end of the motor. Seems like that is the most likely culprit given the quantities I seem to be dealing with.

    I welcome any thoughts and armchair wisdom on the issue and the diagnostic process. I don't want to just change the oil cooler out as it's a pricey part so not sure what the process is. At $125/hr I'm hoping it's not "take stuff apart until we find it".
  2. NYCAP123

    NYCAP123 Senior Member

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    Coolant in the oil should be pretty evident. Milky oil. Oil (or oily substance) in the coolant is a new one on me, and I wonder if it didn't somehow get in from the soot from the exhaust elbow or during the cleanup. (maybe the guy cleaning up took off the cap to clean around there and got some in there?) Hopefully one of the mechanics or engineers here will chime in.
  3. Oscarvan

    Oscarvan Senior Member

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    Syphon it off with a turkey baster and separate. Establish accurate quantity.

    Run the engine and see if it returns. Wrenchers may have used a dirty bucket etc et.
  4. Capt Ralph

    Capt Ralph Senior Member

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    Oil or soot?
    Oil cooler leaking maybe.
    Cracked (water cooled?) turbo also maybe.
    Leaking head gasket maybe.
    If your not getting water in your sump, then you have to think were oil under pressure is getting into the coolant and not coolant into the sump.
    Another suggestion to send your oil to the lab.
  5. Prospective

    Prospective Senior Member

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    Thanks Capt Ralph. Not soot. Oil. Black used oil. I don't believe turbos are water cooled but honestly I'm not sure. Oil may well go to the lab. I have test kits on the way.
  6. Capt Ralph

    Capt Ralph Senior Member

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    If you have a thermal blanket on the turbo, then a dry unit. If exposed with paint still on it, A wet or cooled unit.
    Sorry that I'm not Volvo enough to remember these things, per engine model, off my head.
  7. Prospective

    Prospective Senior Member

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    Interesting, thanks. No thermal blanket so I get could be liquid cooled? Will add it to my list.
  8. Prospective

    Prospective Senior Member

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    Quick look confirms that turbo is indeed liquid cooled. Not sure if that's a likely culprit but will investigate possibility with tech.