Engine flush or drain?

davidbrooksdavidbrooks GermantownMember Posts: 725 ✭✭✭
I wanted to get the experts opinions on how well the 5 point drains work on Mercruisers.  I have a 2003 350 MPI with the 5 point drains.  So i have always fully winterized by sucking up some antifreeze through the outdrives.  This year i am on a lift and really want to take a few trips out later hopefully in the snow.  How safe is it to just open up the drains and let all the water out vs going back through the process of pulling antifreeze through the system?  Any experience here or tips would be appreciated.  It wouldn't be such an ordeal but i have to pull a float around to get to the outdrives.  Not really something i want to do later when it gets bitter out.
It's 5 O'Clock Somewhere!


  • icoulthaicoultha Niskayuna NYMember Posts: 1,902 ✭✭✭✭
    edited November 2019
    in my  opinion flushing is the only way to be sure all water is out of the nooks and crannies. If pink stays in there you’re safe. 
    Post edited by icoultha on



    The Third “B”

    Rear Commodore (2019), Crescent Boat Club


  • Dream_InnDream_Inn Annapolis, MDMember, Moderator Posts: 6,078 mod
    Yeah, I'm on the lift and know exactly what you are talking about.  It sounds like your engines are raw water cooled?  Meaning, you do not have heat exchangers?  If that's the case, I wouldn't trust the pump getting all the water out.  If it was fresh water cooled, I may just use the pump. (although mine are fresh water cooled and I still run pink thru)  I've thought about taking the boat into Annapolis for their parade of lights in December and doing this, but I'm just too ocd about waxing and covering the boat when it needs to be a little warmer to do that.  I also don't like the idea of hanging on the raft in December.  Good luck!

    Dream 'Inn III -- 2008 400 Express

  • davidbrooksdavidbrooks GermantownMember Posts: 725 ✭✭✭
    @Dream_Inn they are fresh water cooled.  I agree with you all that running the pink through is the gold standard.  I just thought i would see what the experts had to say about the wonderful 5 point drain system.  I broke off one of the plugs this summer and while wrestling with it to get it out i found my self asking why i never used it.  Amazing what runs through your head when you are hanging upside down in an engine room getting scratched up from all the sharp corners the mercruiser engineers designed into that engine.
    It's 5 O'Clock Somewhere!
  • Liberty44140Liberty44140 Bay Village & Marblehead, OH.Member Posts: 3,027 ✭✭✭✭✭
    Are you able to put a bilge heater in? If you drained it with the plugs and had a bilge heater you should be ok. I mean a heater designed to be in a bilge, not a home space heater stuck down in the bilge. 

    Also do you have thru Hull intakes? My 350s have water coming in both from the thru Hull and the drives. I run antifreeze through the drives but I could just pour it in the strainer if I wanted to. You could do that fast and easy to be covered if you have strainers. 
    07' Cruisers 390 (Previous Rinker's: 06' 342EC & 01' 310FV)

  • davidbrooksdavidbrooks GermantownMember Posts: 725 ✭✭✭
    @Liberty44140 no thru hull intakes.  Just standard through the outdrive.  I do have a bilge heater. It plugs into the outlet by the topside fridge.  I don't like the idea of relying on that as my primary though. All it would take would be a power outage or tripped breaker and i would be looking at an insurance claim.  I am starting to wonder if there is another way to run pink through the system than by using muffs on the outdrive.  
    It's 5 O'Clock Somewhere!
  • aero3113aero3113 Long Island, NYMember Posts: 5,518 ✭✭✭✭✭
    @davidbrooks , check out this video. He has a lot of videos out that are a huge help.

    2008 330EC
  • GMSLITHOGMSLITHO Greenwood Lake NY Member Posts: 1,057 ✭✭✭
    always ran anti freeze through the drives then drained the block with all my  other boats alpha drives ,the first year with my 270 it has a bravo 3 sea core with the holes in the front of the drive so I winterized with the methoud in the video and had no problems just was a little leery if the anti freeze was getting in all the right places .The past 2 yearsI now just tape up the holes with duct tape and run it through the drives and drain 
  • shawnmjrshawnmjr Detroit MIMember Posts: 1,864 ✭✭✭✭
    If you pull all the drain plugs and use a piece of wire to poke in there to make sure they aren’t clogged and water flows out and then unclamp your hoses and drain them you should be ok. I do that every year but I also run blue -100 before doing that as an extra precaution. 
  • Glassguy54Glassguy54 Member Posts: 588 ✭✭✭
    Just put up a pole building that you can store the boat in and install HVAC! No need to winterize at all. I'm being facectious, of course, but I did have the luxury of having my shop building where we kept our Captiva 246 in climate controlled conditions all year round. It was a trailer boat, so always in the building where I could putz around on it any time of year. Sweltering heat outside? 72 inside. Minus 30 outside? 62 inside. It was awesome and I was indeed lucky!
  • AlswaggAlswagg Member Posts: 2,800 ✭✭✭✭✭
    Glassguy, we seemed to replace at least one engine a year from people who store their boats in so called heated storage condos.  Power outages cause problems with furnaces, and not all come back on automatically.  Next thing you know, temps drop and blocks freeze and break.   We highly recommend that all engines, drives and water systems be winterized if stored in temperatures that typically go below freezing.  
  • Glassguy54Glassguy54 Member Posts: 588 ✭✭✭
    @Alswagg, agree with you 100% on the storage condos, but this was my personal building and I was there running my business every day and I live 5 minutes away from the building, so if there were ever any issues with power or furnace, I could be there in minutes with generators and space heaters. 
  • davidbrooksdavidbrooks GermantownMember Posts: 725 ✭✭✭
    Really i started this thread just to get some opinions on the drain system.  I love the input so far and didn't want it to get off track.  So far it looks like what i have learned is that no one trusts the drains to fully get the water out. Even a little water left in will really mess your day up.  No one so far has come up with a system to quickly drain and or flush an engine with the quickest being demoed on the video https://youtu.be/_bxpqmT1S3c. I guess i was hoping there was a way to open the drains and essentially quickly blow out the water.   So far i haven't found any. 
    It's 5 O'Clock Somewhere!
  • AlswaggAlswagg Member Posts: 2,800 ✭✭✭✭✭
    We drain and flush the systems, but we also leave the blocks manifolds dry.  If you have a Horizon option, you can pump non toxic antifreeze into the system to flush from the inside of motor compartment.   You can buy the Horizon flush attachment and add to any Mercruiser engine 
  • davidbrooksdavidbrooks GermantownMember Posts: 725 ✭✭✭
    Thanks Al.  Is this the attachment that basically adds a garden hose connection to the transom?  I had that on my last boat.  
    It's 5 O'Clock Somewhere!
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