MAINTENANCE OF COOLING SYSTEM

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This topic contains 7 replies, has 4 voices, and was last updated by Tom Easterbrook Tom Easterbrook 4 months, 2 weeks ago.

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  • #10119
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    jdietz17
    Participant

    GREETINGS NORDIC TUG OWNERS,

    As a form of introduction, Paige and I have had our  2005 NT 37-FB for seven years. We live in N. Cal and have boated for years. When our daughter was in orientation for her freshman year at UW, we sat one afternoon at a pub on lake union…. looked around and it became obvious.  Within four months we bought our tug in Anacortes.  Thunder Road is berthed in S. Lake Union.  We have cruised north for the past seven years, getting as far as Ocean Falls.   I am now retired and look forward to more cruising.

    When we bought our boat, seven years ago (and with 500hrs on the motor), we had the after cooler cleaned.  We now have 1500 hrs on the motor and a cummins dealer has suggested taking out and servicing the after cooler, tranny cooler, and heat exchanger,  oh, and while at it, the heat exchanger on the onan generator.   They would take apart, send in to some shop for cleaning, paint, re install.  Well…. that ends up being 30-40 hrs of labor, I am told.  You all know shop rates and can do the math!

    So, I am wondering:   Does anyone know what is recommended about service intervals on  cooling system on cummins motors or know of any references to read about this.  Obviously I want to do what is smart but also don’t want to go “overboard” so to speak.

    Thanks for any info

    #10120
    Bill Robertson
    Bill Robertson
    Participant

    Hi Jim,

    The recommended service intervals for the various engine components are in your Cummins Manual that should have come with the boat.  I’m at home right now so can’t look it up for you.  I had to replace the aftercooler core on my 2001 37 a few years ago due to significant corrosion on the air side of the aftercooler core.  My mechanic told me this damage was caused by running the engine at low rpm all the time and thus not getting the system nice and hot.  He suggested periodically running the engine up to 80% FOT for about 15 minutes or so when heading back to the marina.  Since the new core cost upwards of $2K in 2012 I have had the aftercooler pulled off and inspected every 2 to 3 years.  Am still seeing a little corrosion at the bottom of the core but it can be easily cleaned off to prevent further corrosion.

    I have the engine heat exchanger inspected and cleaned out every 2 years.

    #10153
    Tom Easterbrook
    Tom Easterbrook
    Participant

    Hi Jim,

    I strongly advise that you check out the website: sbmar.com. I have no affiliation with anyone there other than being a contributor when I can help. The site is for a business, Seaboard Marine in California, and is run by Tony Athens who is known as a guru of Cummins diesels. He provides all kinds of free advise on the forums (where he is very active) or in his extensive “Tony’s Tips”.

    Unfortunately Bill is correct, and the raw water side of the cooling system requires regular maintenance! If you regularly freshwater flush the seawater side, this interval can be greatly increased (like doubled). All of the components: fuel cooler, gear (transmission) cooler, and heat exchanger should be taken off the engine, cleaned by at minimum rodding out the passages, but better yet going to the radiator shop, and then pressure tested to ensure no leaks have developed (rad shop can do the testing as well). Depending on a number of factors, this should be done every 2-4 years. The aftercooler requires special attention. It should be taken off the engine and serviced using Tony’s procedures every 2-3 years (if fresh water flushed maybe every 4 years). This is due to the fact that the aftercooler contains many dissimilar metals and corrosion can be a real (expensive) problem and the air side of the aftercooler collects “gunk” and needs cleaned as well. Your mechanic’s estimate of hours seems a bit high to me. I think 20-30 hours seems more like it, however, the removal and installation after the rad shop has cleaned the pieces can be done by a DIYer, even the aftercooler. I just did my aftercooler. By the way, the aftercooler MUST be pressure tested as an internal leak could put seawater in your engine (very bad :)).

    While on this topic, I highly recommend installing an exhaust hose temperature alarm (material cost about $80). There are 2 brands that I know of: Borel and Aqualarm. Basically these alarms monitor the raw water side. This looks like a big “zap strap” and is installed on the exhaust hose right after the raw water injection point (exhaust elbow). This is the first place that an overheat will show up and the early warning provided by these alarms could save you big bucks. Mine alarmed 2 summers ago and alerted me to an internal leak in my (then) failing exhaust elbow. If this had gone undetected (and it would have without the alarm) my engine or turbo could have ingested saltwater. BIG PROBLEM  if it did that!

    Hope this helps,

    Tom Easterbrook

    Pilitak NT 37-068

    #10159
    Bill Epler
    Bill Epler
    Participant

    Being a new NT owner the previous posts were very educational for me. I then did some internet searching and found a product named Barnacle Buster that can be used with coolers in place. Attached is a You Tube video of the process. If it is as effective as claimed then its should extend the time between physical removal. I posted on the Cummins Marine Forum at Seaboard Marine asking for experience people make have had.

    Bill

    Mora NT32-111

    #10190
    Tom Easterbrook
    Tom Easterbrook
    Participant

    Bill,

    I concur with the Seaboard forum responses you received. That is, you can increase the time between required disassembly and cleaning of the raw water cooling system (best) by regularly freshwater flushing the system after use anytime you are on a dock where there is a good supply of freshwater (good meaning reasonable flow available). This takes less than 10 minutes to do, start to finish.

    As an added precaution,I flush using “Saltaway” prior to winter layup, and leave that in all winter. Following this protocol, I expect to get 5+ years between sending the components to the rad shop assuming I don’t destroy an impeller or leave my zincs in too long and have zinc pieces reducing flow. However, I am still going to remove the aftercooler for a full service every 3 years.

    Regards,

    Tom Easterbrook

    #10191
    Bill Epler
    Bill Epler
    Participant

    Tom, could post a photo, or describe, how you hookup the fresh water supply to the system?

    Thanks,

    Bill

    #10207
    Tom Easterbrook
    Tom Easterbrook
    Participant

    Bill, I am away right now and don’t have access to those photos, but will post on the weekend.

    However, the cap to the seawater strainer (Groco), has a “garden hose” style connection with a shutoff embedded in it. Just connect a dock supply hose to that connection, open the through hull to allow the pressure to exit the bottom of the boat, turn on the dock water, and start the engine. After it is running, close the thru hull and run for however long you want to flush. I do about 3-5 minutes. At shutdown, close the freshwater shutoff at the same time or slightly before shutting down the engine! You do not want to be pumping pressurized water into your engine when it is not running! Disconnect the hose with a bucket nearby to minimize any spillage and you are good to go. This also helps to “backflush” your raw water intake, possibly reducing sea life buildup.

    This is not the only method possible, but it is simple and easy, and it is Tony Athens approved😎

    Hope this helps you picture what I mean,

    Tom Easterbrook

    #10208
    Tom Easterbrook
    Tom Easterbrook
    Participant

    Hi Bill,

    Here is a photo of the setup on my main engine seasick.

    Hope this helps,

    Tom Easterbrook

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