Water Pumps, Heat Exchange Zinc and other mysteries!

Discussion in 'Main Morgan 38 Sailboat Forum' started by Marc H. Pearl, Apr 21, 2019.

  1. Marc H. Pearl

    Marc H. Pearl Member

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    Could use some insight to the mysteries of boat maintenance.

    I have two pumps that are a mystery. They are connected electrically and plumbing but I can't figure out what they are (or were) for.

    This on is behind the engine water muffler in the engine room. Behind engine water muffler.jpeg

    This one is under the sink in the head.
    Pump under head sink.jpeg

    Is this a zinc on the top of the heat exchanger? Either it's just a plug or the zinc is completely gone on this one. If it is a zinc, what size and where can I buy a replacement?
    IMG_2543.jpeg
    IMG_2544.jpeg
     

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  2. jimcleary

    jimcleary James M. Cleary

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    The pump under the head sink is in the same location as the shower sump drain pump on my boat. The one behind the muffler is a mystery. Could you trace the inlet and outlet hoses and tell us where they come from and go to?

    The plug from the heat exchanger doesn't look like a zinc fitting. Maybe one of the Perkins owners would know more about it. I have the Yanmar engine.

    Jim
     
  3. terry_thatcher

    terry_thatcher Terence Thatcher

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    on my perkins, the heat exchanger zinc bolt is on the aft side of the exchanger. But you need a zinc, so if you have no other hole in the exchanger, you might check to see if a short zinc will fit i to the hole you have here. they screw i n using a nut like you show in the picture.
     
  4. terry_thatcher

    terry_thatcher Terence Thatcher

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    One other thing. Some boats had electric pumps to drain the ice box. The aft pump you show has a small inlet hose. That may be its us. Just a guess.
     
  5. rickdowe2

    rickdowe2 Richard Dowe

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    That plug you are holding looks like the vent on the heat exchanger for the engine. The plug is on the close- loop coolant side. After filling the system loosen the plug until antifreeze comes out.
     
  6. Travis

    Travis New Member

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    I have the same heat exchanger on my Perkins 4.108 and recently pulled it and the oil cooler to have them serviced. As Terry said, the plug you are holding is not the zinc. It is the high-point air bleed for your cooling system (It is not technically the highest point in the system but it is the quickest way to get most of the air out of after service)

    There should be two more identical-sized plugs on the bottom of the unit, which are for winterization of the cooling system (i.e. for draining it). The zinc-containing plug, as terry mentions, is toward the port side, facing aft and downward at an angle. It is larger than the plug you are holding (see link below for photos) and it has a recess where new zincs can be screwed in to it.

    Would highly recommend pulling the heat exchanger and opening up the end cap to visually confirm that the internal copper tubes are all clear. My zinc plug had long lost its zinc, the plug itself was galvanically-corroded in-place, the internal copper tubes were about 30% obstructed with scale, and there were plenty of little bits of impeller floating around in there to boot!

    Here is a link to an identical unit - you can see all of the bleed/drain/zinc caps in the second photo:
    https://www.mrcool.us/na001406-perkins-heat-exchanger.html

    The Perkins cooling system is dead simple so don’t be afraid to take some ‘before’ photos and start pulling hoses and components...it’s all pretty straightforward. Coring the heat exchanger and oil cooler should run about ~$100 apiece at a reputable radiator shop.

    These heat exchangers are beasts so you’re probably fine but if you end up needing replacements, I would not recommend ordering from Mr. Cool, the site linked above. These parts can be found for cheaper through Perkins suppliers.

    Good luck! I have photos of the whole teardown and refurb of the units so let me know if you need more info and I’ll dig em out.
     
  7. Marc H. Pearl

    Marc H. Pearl Member

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    They may be straightforward but a bitch to get to. Thanks all.
     
  8. Marc H. Pearl

    Marc H. Pearl Member

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    Thanks Jim -

    That makes sense that the pump under the sink is for the sump. Questions, is it really necessary to have a shower sump? I get it's a good idea to keep hair out of the bilge but it seems like one could rig a screen where it drained into the bilge to catch any hair. BTW, where does my sump pump to, overboard?
     
  9. Travis

    Travis New Member

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    True - they do cost a little bit of knuckle skin
     
  10. Travis

    Travis New Member

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    Mine pumps the shower water aft through a 1/2” line to a fitting on the port side of the ‘scupper drain’ pipe below the cockpit drains. I have wondered the same thing about the shower sump and the impact that draining it to the bilge would have. I’m sure there are a few good reasons. Will be interesting to hear what others say..
     
  11. terry_thatcher

    terry_thatcher Terence Thatcher

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    Every expert I have read says do not drain shower into bilge. Smell, hair, soap crud. You want the bilge clean. My pump is under the head sink, I wouldnt remove it. I have replaced it once in 20 years. Worst thing that happens is occasionally it loses it prime over the winter and I have to disconnect a hose and help it get started.
     
  12. terry_thatcher

    terry_thatcher Terence Thatcher

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    Travis, what condition did you find in the oil cooler? I recently replaced all oil hoses, as preventive maintenance and had the heat exchanger serviced, but have not removed the oil cooler. Doesnt look easy to get it out. Does it have cooling chambers like the heat exchanger? Were yours clogged at all?
     
  13. Travis

    Travis New Member

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    Terry,
    You’re pretty much right on the money. It is built very similarly to the heat exchanger. Maybe it is because it only sees clean water, but the interior of the unit seemed to be in stellar condition - and wouldn’t have needed to be pulled in my particular case - but now I know for sure that it is clear. We began the overhaul because I had an impeller crumble and all-but-disappear into the cooling system, so seeing things gave me peace of mind that it ended up working its way through. You are right, the bolts that fasten the retaining bracket were a royal pain to get loose, not to mention the hoses!

    I sandblasted and repainted it but as I said, the core and interior looked perfect, for lack of a better word.

    Putting it all back together in that tight area through the quarter birth access door took time, and requires a certain level of flexibility. Lots of blind wrenching. The order-of-operations took some trial and error to figure out. The heat exchanger reinstallation was a walk in the park by comparison.
     
    Last edited: Apr 23, 2019
  14. john Gonzalez

    john Gonzalez Member

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    Mark, if you do not have a hand pump for your ice box located on the other side of the galley bulkhead, accessable by a small door, I bet the other pump behind the muffler is for your ice box and drains into your cockpit drain manifold and out the torpedoes. Jim is right about the other pump. The heat exchanger plug is just a guess as I have a Yanmar, but it looks way to small for a zinc plug.
     
  15. jimcleary

    jimcleary James M. Cleary

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    Marc

    I think it's best to keep "grey" water out of the bilge. Even if you screen the hair and solids out, there will be many other contaminates left to stew in the bottom of the boat. Not a healthy situation. Not to mention a malodorous situation. Our pump, that lives on that shelf under the sink, discharges into the sink overboard thru hull via a tee fitting. There is also an inline filter before the pump to catch the hair and soap crud. During the season I have to clean out that filter more times then I want, but the alternative to not doing the job is much worse.

    Jim
     
  16. dave_a

    dave_a Dave Ahlers

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    Travis, - Before you pull the Perkins heat exchanger apart, find the model number and order an end cap gasket kit. Your gaskets may come out in pieces. Soak it all parts in vinegar for a day or two and gently poke thru the tubes with a rod to get the junk out. Re-soak, repeat. My exchanger was a Sendure model. Parts available from them from that company.
    You can buy a too long zinc at West Marine, and cut it down to proper length. Make sure its short enough to not touch the core (like I didn't), that way it wont break off the brass, Aad give you the chance to take the whole damn thing out again. It has a large brass bolt head on it. 5/8 or 3/4" if I recall correctly.
    With respect to your oil cooler: strongly recommend you have new pressure hoses made up for the connections to and from. They're 40 year old rubber. You will not be quick enough to kill the engine when the alarm goes off (indicating no oil pressure) to prevent damage. The hose will burst not leak. And it will only happen at the worst possible time.
     
  17. dave_a

    dave_a Dave Ahlers

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    Sorry, meant Marc.
     
  18. Travis

    Travis New Member

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    Well, it applies to me too, somewhat - you make a great point about the oil pressure alarm. I have never tested mine and I’m not positive the alarm itself even works. Also a good suggestion regarding the hoses - I think I ought to do the same..

    Wholly agree with the other advice about the heat exchanger!
     
  19. Marc H. Pearl

    Marc H. Pearl Member

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    Update; I located the zinc on my exchanger, the bad news is it appears the zinc rod is still in the exchanger (must have broken off as described can happen if it is too long in earlier post,) good news is it isn't corroded. I wonder if it is possible to pull it out with one of those bits that is used to back out broker off bolts.
     
  20. rickdowe2

    rickdowe2 Richard Dowe

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    Hi Marc, if you take the end plate off from the heat exchanger you will see the remains of it in that cavity. What typically happens is the zinc will waste away and some of it will plug up the hole that the plug was removed from. The end plate is facing the port side. If you don’t have access from that side you can use a mirror. The gasket on the end cover is just a thin rubber material. Auto stores should have raw stock you could purchase. Rick
     
  21. rickdowe2

    rickdowe2 Richard Dowe

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    The zinc is soft so you should be able to pick it out.
     
  22. rickdowe2

    rickdowe2 Richard Dowe

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    Marc, I had my cooler open this weekend and took some pictures.
     

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  23. Marc H. Pearl

    Marc H. Pearl Member

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    Thanks all, great advise.

    Richard, were you just bored and decided to open up your heat exchanger this weekend?

    Another question while I have your attention. The fresh water supply connection (to the boat fresh water, not the engine) aft of the cockpit looks like an intake to be connected to a fresh water hose from shore. If I take out the one way valve would it be pressurized to use for an outdoor shower?
     
  24. rickdowe2

    rickdowe2 Richard Dowe

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    Haha, I am getting ready for my boat to splash Friday and I had to replace a couple hoses on the engine. After I rebuilt the engine I used a couple of hoses that were the right size but not the correct type. So I had to pull everything out of the port later lazarette. For winter layup I remove the end cover and blow it out.
    As far as the water, if you remove the guts from the unit it should allow water to pass.
    Rick
     

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