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  • #24372

    firehoser75
    Participant
    Engines: Cummins 6BTA M3-330 HP
    Location: Nanaimo, BC
    Country: Canada

    I have experienced an adverse reaction in my antifreeze coolant and am looking for help.
    My new to me boat (Sept. 2016) developed an overheat on the exhaust hose. It turned out to be an exhaust elbow that was corroded. Caught it in time prior to turbo damage. As part of the work, the mechanic changed the antifreeze. The old antifreeze was green, but he put in Prestone Command Extended life (red). He did not flush, but did mix it with distilled water. I have run the engine about 70 hours since, but at low RPM (1400). It is a 6BTA Cummins (2002) 330 hp. I have not noticed any gunk (yet) in this engine.
    Ten days ago, I changed the antifreeze in my Onan generator using the same procedure (from green to red). Yesterday, when I finally received my new rad cap, this is what I found inside the filler neck and on the rad cap. (See photo). The gennie has only been run about 10 minutes since the change. Prestone has told me (before the gen set coolant change) that their Command product is compatible with ANY (their capitals) antifreeze and ANY engine. Obviously not. How do I clean this out and what do I install next? Sorry, but the photos seemed to “invert” on their own when uploaded.
    Thanks for your advice,
    Tom

Viewing 5 replies - 1 through 5 (of 5 total)
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  • #24421

    Bill Fuller
    Participant
    Vessel Name: Audax
    Engines: Yanmar 4LHA-STE
    Location: San Diego, CA
    Country: USA

    I agree with Tony.
    I can pretty much guarantee that you DID NOT have any sort of reaction between the 2 different coolants.
    The gen set already had the problem. You just noticed it when you started doing the maintenance.
    Bill F.

    1 user thanked author for this post.
    #24401

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    I personally do not think you had a “Adverse Reaction”.. I think you have a 14-15 year old coolant system in your Onan that has been neglected from Day 1.. Get yourself a manual to see if it shows you how to drain the system,, if not then you just have to figure it out… Then figure our a way to flush with clear tap water ( water to the top and out the drain? .. Then fill with Tap water run until it gets hot ( under load) and drain again.. Maybe 2-3 times? Then drain and refill with the proper coolant.. Test all..

    Tony

    1 user thanked author for this post.
    #24400

    firehoser75
    Participant
    Engines: Cummins 6BTA M3-330 HP
    Location: Nanaimo, BC
    Country: Canada

    A little more info. Yesterday when I checked, the Cummins engine coolant it looked normal when I took off the radiator cap. I removed some using a new straw. The new red coolant (70 hours ago) looked “normal”, that is clear and clean with no “thick looking gunk”. The overflow (clear) tank looked clean and clear as well. The Onan, which now has the same new coolant, is not looking good (coolant wise). The photo in the first post shows “some” of the thick gooey gunk that was visible at the filler neck. The coolant in the recovery tank looks fine.
    My question is how to deal with this problem. Because of the adverse reaction in the generator, do I also deal with the Cummins the same way as a precaution even though it currently does not show the same reaction?
    Thanks,
    Tom

    #24376

    firehoser75
    Participant
    Engines: Cummins 6BTA M3-330 HP
    Location: Nanaimo, BC
    Country: Canada

    Little History

    Hi Tony,
    Thanks for your prompt reply. I have little history on this unit. It has 619 hours on it. It has always been run in salt water. The boat has had 2 previous owners, both of whom owned it for 7 years each. The second owner only put about 150 hours on the gen set. It has been regularly freshwater flushed. I now have a history of 2 oil samples both of which were very good. The unit is in an enclosure and looks to be well looked after. There was some visible corrosion where the exhaust elbow bolts on to the coolant tank. I took this apart only to find that the gasket was never installed from the factory. I cleaned up the connection and reinstalled with a new gasket. The elbow looked to be in good condition. Other than the enclosure base, the unit looks almost new (at least from the outside). The Onan was put in service in 2002 and is an MDKAV 9kw. The coolant that was removed looked clear and clean, being a green color. That’s about all I know about the Onan except that I put about 80 hours on it this year and it ran well.
    Thanks,
    Tom

    #24375

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Firehoser,

    I cannot give you an answer yet as there is way too much history missing……………………….Exactly how old “Marine Age” wise is the ONAN?

    The Onan was put is service when? Always in salt water?………

    History of past coolant changes? Hours and dates..

    Tony

Viewing 5 replies - 1 through 5 (of 5 total)

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