Heat exchanger on 4-108 low line

  • November 25, 2012 2:46 PM
    Message # 1145639
    Deleted user

    Does any one have a drawing of the heat exhanger (including tubes and tube sheet)mounted at the rear of a Low-Line Perkins 4-108.  I have no raw water flow out the exhaust and suspect a plugged exchanger.  Want to know what I'm in for before I remove and try cleaning it.  Of course, need to check mixing tee first.

  • November 25, 2012 3:55 PM
    Reply # 1145664 on 1145639
    I know this is kind of a no-brainer, so not meaning to insult but... 

    Have you checked that: 

    1)  Raw water seacock is open
    2)  Raw water strainer is not clogged
    3)  The impeller on the engine is in good condition. 

    I would make sure I know for sure all these are done before pulling apart the exchanger itself. 
  • November 26, 2012 5:28 AM
    Reply # 1145992 on 1145639

    Tate's recommendation is a good start. While your problem could well be within the heat exchanger, there are a number of other things you might want to check first. There are several good references online to help diagnose the situation. Following are a couple of good ones...

    Also, be aware that the Perkins 4.108 used different heat exchangers through it's life. Mine uses a Bowman exchanger, but the engine is a 1987 model. I believe earlier models were different. And, unless you know the full history of your boat & engine, it's possible that the heat exchanger installed was not the original type.

    If you insert a photo of your engine/heat exchanger, it will be easier to tell what drawing/diagram applies.


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  • November 26, 2012 6:05 AM
    Reply # 1146005 on 1145639
    Deleted user
    The first thing checked was raw water flow through strainer to pump.  Checked full flow.  Pump impeller was changed.  So problem is downstream of pump.  Old impeller had a bit missing from 2 or 3 vanes, but not enough to cover exchanger tube inlets.  (Raw water flows thru tube side so tubes can be cleaned; engine coolant on shell side).  This exchanger looks like a two-pass tubes-side, one-pass shell side but construction is most unlikely to allow bundle to be pulled.  Looks like it woill have to be removed entirely and cleaned as a unit.  The only other possible blockages are mixing tee, and muffler.  However, exhaust flow thru muffler is quite good.  Just thought someone might have a drawing...
  • November 26, 2012 5:23 PM
    Reply # 1146460 on 1145639
    Per my earlier reply... "If you insert a photo of your engine/heat exchanger, it will be easier to tell what drawing/diagram applies".

    Try this link for Bowman: http://www.tadiesels.com/bowman.htm

  • November 26, 2012 5:23 PM
    Reply # 1146461 on 1145639
    Deleted user
    Thanks for the links Jack.  The first one made a bulb light up.  The exchanger has a cover on the raw water inlet end, held in place with a single bolt.  This weekend I will remove the cover and check for missing bits of deceased impellers.
    Last modified: November 26, 2012 5:24 PM | Deleted user
  • January 05, 2013 7:06 PM
    Reply # 1172610 on 1145639
    Deleted user
    I thought I had posted a confession here a few weeks ago, but no, it's not here.  Turns out that the raw water line between pump and heat exchanger had a manifold with a shut-off valve to direct water to an engine driven refrigeration compressor on its way to the engine's heat exchanger.  When I switched out the oil cooler I turned off the valve and forgot to turn it back on again, hence, no water flow.  Yet another lesson that answers are usually found in the simplest places.  Also a nice example of why tag-out lock-out procedures are important to observe in the refineries and gas plants I deal with frequently. ;-) --- think I'll start the same procedure on the boat as my memory is sometimes a poor servant.
    Last modified: January 05, 2013 7:07 PM | Deleted user
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