How to seal bilge pump mounting plate?

Discussion in 'General Maintenance/Repair Questions' started by rcflyyer1, Jun 24, 2020.

  1. rcflyyer1

    rcflyyer1 Member

    32
    Apr 8, 2019
    Sarasota, FL
    280 Sundancer 2002
    Twin 4.3L V6 Mercruisers w/ Alpha One Drives
    Hello all,

    Getting ready to put in some new bilge pumps in my 280 Sundancer. The boat has the Rule 1100 27D models and I'm putting in Rule 1100 27DA pumps. Unfortunately, the pumps use different mounting-bracket designs, but the screw patterns are the same. On all of the guides I've read, many suggest to use a mounting plate and to never drill into the hull, but since the old ones are drilled directly into the hull, I think I should be fine to re use the old holes.

    On the mounting-bracket, I saw some type of white/yellow sealant used. It was oozing out of the screw holes as well as all over the bottom of the mounting-base. What new sealant should I use when I screw the pumps down? Would 3M 4200 work? I was thinking about coating the screw threads and bottom of the plastic base in 4200 and then screwing it down. Does this sound like a good idea?

    I did tons of searching online and couldn't find anything pertaining to using sealant AND directly drilling in a bilge pump mounting bracket, so hopefully this thread can help others as well.

    Thanks
     
  2. sbw1

    sbw1 Well-Known Member

    Oct 10, 2006
    West Michigan
    This is listed in my signature
    This is listed in my signature
    FullSizeRender.jpg 3M says 4200 is for use above and below the water line. So yes, you should be good to go. I would suggest you allow several days for it to cure before getting it wet. It will cure when wet but it takes much longer.
     
  3. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    It shouldn't be drilled/screwed into the "hull". There should be a wood block glassed to the hull and then the pump screwed to that wood block. If it's screwed into the hull, that was not done by the factory.

    I wouldn't glue the plastic base to the hull with 4200 (it is, after all, an adhesive sealant). All that would do is make removal in the future way harder than it should be. You could use a small dab on the screw hole and then some on the threads before screwing in - that would be more than enough. There's other products that can work, too, such as BoatLife LifeSeal, but pretty much anything can work here.
     
  4. sbw1

    sbw1 Well-Known Member

    Oct 10, 2006
    West Michigan
    This is listed in my signature
    This is listed in my signature
    FullSizeRender.jpg Hard to know exactly how the pump is attached based upon the information provided. But 4200 is intended for use when future disassembly is anticipated. It makes sense to adhere the pump with a good sealant that is removaable.
     
  5. rcflyyer1

    rcflyyer1 Member

    32
    Apr 8, 2019
    Sarasota, FL
    280 Sundancer 2002
    Twin 4.3L V6 Mercruisers w/ Alpha One Drives
    Thanks for the information! Sounds like the 4200 should work well, but just need to pay attention to how it's applied. Now that I look at the photo, definitely doesn't look like it's directly in the hull. Rather it looks like a raised-levelled section above the keel.

    Apologies since I should have posted a photo from the beginning. Please excuse the oily residue. A nice cleaning will be the first step to the installation.
     

    Attached Files:

  6. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    It's just still pretty tenacious, is all. In this case, it's tiny little bilge pump that is held, more than enough, by the mechanical action of the screws. Nothing wrong with using it - but pumps are often in hard to access areas where it can make it harder then necessary to remove it. Plus, the only thing needing sealing is the actual screw holes.

    At least he didn't say he was going to use 5200! After all, apparently, according to many forums, 5200 is the be all, end all of sealants and should be used everywhere ;)
     
    kvduff likes this.
  7. Golfman25

    Golfman25 Well-Known Member

    Sep 12, 2009
    IL
    281
    V8
    So when I first got my boat many years ago, the wood that the bilge pump was on detached from the hull bottom. I went ahead and fabricated stainless steel brackets to mount above the bilge water and then sit down on the hull bottom. Added and extra pump too. Worked awesome and haven't had to touch in years.
     
  8. rcflyyer1

    rcflyyer1 Member

    32
    Apr 8, 2019
    Sarasota, FL
    280 Sundancer 2002
    Twin 4.3L V6 Mercruisers w/ Alpha One Drives
    After a long day and sore legs, I got one pump (the secondary pump) in and working. I tried to do the primary pump (front) first but ran into issues as the new pumps have back flow prevention valves that extend the necks by a good inch or so. Not going to work with the current position of the previous pump.

    I will have to drill two new holes to move the pump further away from the structure in order to get everything to fit. I was contemplating just attaching the hose to the pump's neck without the back flow prevention valve (which shortens it) but decided against it since I'm not sure it's advisable.

    The pumps are mounted on a raised section of the bottom of the bilge. If I move the mounting bracket over (as seen in the picture) will this cause any problems? I won't go deeper than the length of the screw and all holes will be sealed with 3M 4200. I just don't want to drill into any hidden wires or plumbing.

    Thanks
     

    Attached Files:

  9. b_arrington

    b_arrington Well-Known Member GOLD Sponsor

    Feb 21, 2007
    Setauket, NY
    2018 Back Cove 34
    Cummins QSB 6.7 480
    I'm surprised that the new pumps would have anti-backflow valves. Those are generally a no-no for bilge pumps. The potential problem is the valves getting jammed, or the pump not being able to overcome the static pressure of a column of water sitting on top of the valve and holding it shut.
     
  10. rcflyyer1

    rcflyyer1 Member

    32
    Apr 8, 2019
    Sarasota, FL
    280 Sundancer 2002
    Twin 4.3L V6 Mercruisers w/ Alpha One Drives
    Hmm this makes me question whether just unscrewing the back flow valve all together would be okay. It looks like a pretty slick setup with pre-greased threads and an o-ring so the attached neck containing the valve seals properly. The thought of clamping down the bilge pump hose to a threaded neck made me question my motive. If this can be done, I might not have to reposition the pump mounting tray as it would barely fit.

    Here's the valve that came with my pump: https://www.thechandleryonline.com/product_info.php?products_id=10767
     
  11. rcflyyer1

    rcflyyer1 Member

    32
    Apr 8, 2019
    Sarasota, FL
    280 Sundancer 2002
    Twin 4.3L V6 Mercruisers w/ Alpha One Drives
    Do you think it would be okay to attach the hose directly to the pump’s neck without the nozzle connected? 4332F45A-F1E0-4053-9CBB-194046E7CED0.jpeg C6418C47-5D4E-4A42-B680-509A6E075B5C.jpeg
     
  12. b_arrington

    b_arrington Well-Known Member GOLD Sponsor

    Feb 21, 2007
    Setauket, NY
    2018 Back Cove 34
    Cummins QSB 6.7 480
    will it fit? And what does the nozzle look like?

    The link to the valves is interest as it says it’s for the “new style of Rule pumps”. Maybe something changed about the prohibition on back flow valves?
     
  13. rcflyyer1

    rcflyyer1 Member

    32
    Apr 8, 2019
    Sarasota, FL
    280 Sundancer 2002
    Twin 4.3L V6 Mercruisers w/ Alpha One Drives
    Appears that it will fit fine as the diameter of the built in neck is between the small and large nozzles included. Here you can see the size difference that’s causing the issues. EB9F1DE2-78C6-4B91-9148-6234C8056A51.jpeg
     
  14. Little Ducky

    Little Ducky Well-Known Member

    Jun 5, 2017
    Dickson, TN / Chattanooga, TN
    1998 290 Sundancer
    Twin EFI 5.0L w/Alphas
    Kohler 4kW
    I feel your pain...... well not really.

    Last year I had a bilge pump fail so I had both replaced while the guy was in there.

    I'm glad they hire thin, long armed mechanics. My fat butt, stubby armed frame wasn't getting close to touching where they put these things between the twin 5.0's in the 98 290 SD.
     
  15. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    You should have no issues of remounting the pump to a slightly different location. As you can see, it's a flat area which means (as mentioned above), you're not actually mounting to the actual hull. Also, note that you can see a piece of plywood glassed into that area for mounting.

    From what I know, the whole reason for having the backflow preventer (which not all boats have, by the way) is simply to keep that slug of water in the hose from coming back down into the boat. You can eliminate if you want to - although the merits of it could be discussed. 6 of one, 1/2 dozen of the other kinda thing.

    If the hose fits over the neck and seals well enough - sure. Worst case, you might get a VERY small amount of leakage. You could always use something like Merc's (or Quicksilver) Perfect Seal. Don't overthink this - just get 'er done!
     
  16. Bt Doctur

    Bt Doctur Well-Known Member

    Aug 21, 2010
    New Jersey
    Ex SRV 240 Weekender twin
    in between
    Although I would install a pair of 1800 gph pumps
     
  17. KEVIN D TOBIN

    KEVIN D TOBIN New Member

    22
    Jun 12, 2018
    1993 290 sundancer, 7.4L mercruiser repower 2018
    7.4L Bravo ll drive
    I connected both of my pumps to a piece of aluminum and bent it so one fits at the very bottom of the bilge under the engine and the other is the high water pump, both are screwed to the main stringers, so any maintenance is a lot easier
     
  18. rcflyyer1

    rcflyyer1 Member

    32
    Apr 8, 2019
    Sarasota, FL
    280 Sundancer 2002
    Twin 4.3L V6 Mercruisers w/ Alpha One Drives
    Thank you to everyone for your great help!

    The job has been completed and I verified by someone outside the boat that the flow rate is very good on both pumps. Here is what I ended up doing.

    The secondary pump was able to be mounted using the original holes. The elongated nozzle was no problem with this pump as it is placed further away from the "wall" structure. The primary pump was a different deal and I decided to relocate due to the interference of the wall structure with the hose mounting. I moved the holes about 1 and 1/2 inches to port from their original location and this gave me just enough room to mount the hose.

    Another big roadblock was the hose mounting process itself. The corrugated hose that is used in the boat is a very specific size that will not fit properly over Rule's small and large nozzles. I also tried mounting the hose to the threaded portion of the pump (nozzle removed) and it wouldn't fit. I was about to grind the threads down on the pump body, but decided to grind the large nozzle down a bit instead. I used a dremel and sanding wheel to remove the ridges on the pump nozzle and that was just enough that the hose now cleanly slides on with slight force. The added benefit is that the dremel wheel roughed the nozzle up which should provide additional grip. Then, I tightened the clamp to complete the job.

    All in all it was a lot harder that I expected, but I learned a lot in the process. The only last thing to do is replace a broken mounting-tie (I probably broke it) that keeps the hoses inclined. Don't want to cause an air lock.
     
    Last edited: Jul 3, 2020
    R-and-R likes this.

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