Cummins Marine Diesel Repower Specialists › Forums › Cummins Marine Engines › 1999 6BTA 5.9 M-3 (older style) Heat Exchanger replacement

  • This topic has 7 replies, 3 voices, and was last updated 4 years ago by Paul.
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  • October 1, 2019 at 9:08 am #78689

    Paul
    Participant
    Vessel Name: Changes in L'Attitudes
    Engines: Twin Cummins 330HP 6BTA 5.9-M-3
    Location: Merritt Island, FL
    Country: USA

    Was seeing signs of the heat exchanger going over the last few month (expansion tank level, engine temps creeping up) and when the alarm started sounding after running at high RPMs after about 5 minutes (temps creeping above 200F) I knew it was time to pull it.

    Of course it’s the starboard engine, so the heat exchanger is outboard, real PIA to take out. Soaked it (estimate about 1/3 of tubes with at least some blockage) and then pressure tested and it just wouldn’t hold for long. So, time to replace.

    Checked Seaboard’s parts – you folks have one of the newer style (Champ) and of course, I need the older Sendure (looks like the original was PN 3866719, later replaced by 4019958). Found a new one on eBay, order is in … will update when it arrives.

    I’m going to start doing my old fat guy yoga now so I can get outboard and do the replacement.

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  • November 8, 2019 at 1:45 pm #81121

    Paul
    Participant
    Vessel Name: Changes in L'Attitudes
    Engines: Twin Cummins 330HP 6BTA 5.9-M-3
    Location: Merritt Island, FL
    Country: USA

    Well, this project took forever.

    Life, even when retired, intervenes and stops you from getting to the boat, doing work, and then doing sea trials to make sure everything is good to go. So, after a long delay I can report the HE in, dock and sea trials completed SAT and temps stayed right at 175F-180F through a 20 minute WOT run (lots of race tracks). I take the ‘do the after cooler’ comments to heart, and as mentioned, they’re in the budget (at least as planned) for when the boats on the hard next year, but right now, they seem to both be fine.

    October 18, 2019 at 2:47 am #79466

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

    Paul,

    Do yourself a favor–Since you really do not know the internal condition of the “other seawater components”, service them all..

    Seawater pump (not just the impeller), the aftercooler ( put it on the bench and remove the core & service per my protocol), gear cooler, and then your heat-x…………………..Experience has shown conclusively over the past 25 years with this cooling system design, the heat-exchanger is the least likely cause of system overheating/ temp creep….

    Tony

    October 16, 2019 at 2:01 pm #79393

    Paul
    Participant
    Vessel Name: Changes in L'Attitudes
    Engines: Twin Cummins 330HP 6BTA 5.9-M-3
    Location: Merritt Island, FL
    Country: USA

    Part in hand … now to start stretching my back

    HE arrived today … time to start stretching so I can climb outboard and hook’r up.

    October 2, 2019 at 1:53 pm #78775

    Paul
    Participant
    Vessel Name: Changes in L'Attitudes
    Engines: Twin Cummins 330HP 6BTA 5.9-M-3
    Location: Merritt Island, FL
    Country: USA

    Definitely did need to replace the Heat Exchanger

    While it cleaned up well after a good soak, the fact that I couldn’t get it to hold pressure and the discoloration that I was informed it caused by the alloy changing (can’t recall now if it’s tin going in or out?) told me it was time to bite the bullet and replace it before it got worse.

    Agreed, after cooler very important, and as I mentioned, it’s on my list of to do’s for preventative maintenance next year. A man has to stay with in budget or the boat goes no where šŸ™‚

    October 2, 2019 at 11:51 am #78750

    Mike Uliasz
    Participant
    Vessel Name: Runnin' Down a Dream
    Engines: Cummins 6bta-M3 370hp
    Location: Mathews, VA
    Country: United States

    Just purchased my first diesel boat this summer and did exactly what you did, pulled the heat exchanger when one engine started running above 190 and posted some questions on the forum. Tony recommended to pull and do the after-coolers also saying ā€˜way more importantā€™ so thatā€™s what i did. Replaced the impellers too. Runs just below 180 now. Might not need a heat changer?

    October 2, 2019 at 7:38 am #78731

    Paul
    Participant
    Vessel Name: Changes in L'Attitudes
    Engines: Twin Cummins 330HP 6BTA 5.9-M-3
    Location: Merritt Island, FL
    Country: USA

    Next on the list

    I decided to do the heat exchanger first because the last time a maintenance entry was made about it was a flush in 2013 (previous owner kept fairly good maintenance records). The aftercooler was noted as being cleaned in the spring of 2016. I have the aftercoolers on my 2020 (probably late in the year) preventative maintenance list but will move them up if the heat exchanger replacement doesn’t seem to do the trick.

    October 1, 2019 at 1:06 pm #78697

    Mike Uliasz
    Participant
    Vessel Name: Runnin' Down a Dream
    Engines: Cummins 6bta-M3 370hp
    Location: Mathews, VA
    Country: United States

    Did you check the after-cooler for blockage? Bottom of core was where my blocked up the most.

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