Mercruiser 5.0 1(a) - MPFI Single Point Drain Cooling System (Complicated)

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  • Опубліковано 7 лют 2025
  • In this video I describe how water flows through a single point drain system on a Mercruiser 5.0 MPFI marine engine. It’s so complicated that I had to document the system before disassembly or I would struggle putting it back together. Hopefully this helps those who may have gotten a boat in pieces to put it back together.

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  • @mikedodd9294
    @mikedodd9294 3 роки тому +2

    great video, I learned a lot. Looks just like my 350 MAG MPi.

    • @moccasinmarine
      @moccasinmarine  3 роки тому

      Glad it helped. I’m going to ask the customer if he wants me to convert it into a true single point drain by installing the handle operated drain valve but he lives in Florida so he may not want to add it. He told me he never drained it anyway.

  • @BellavistaPEI
    @BellavistaPEI 3 роки тому +1

    Very informative video! Thanks for taking the time and posting it!!!

  • @TaylorTaylor-yi4qd
    @TaylorTaylor-yi4qd 2 роки тому

    Thank you for explaining the cooling system. I having a hell of a time tracking down a coolant issue. At idle it runs around 170 get on plane jumps up to around 200. Risers are cold to the touch but the thermostat housing is hot to the touch. New long block with new thermostat and circulation pump (one that car guys call a water pump)

    • @moccasinmarine
      @moccasinmarine  2 роки тому +1

      Your risers are cold because the raw water pump constantly pumps raw water to the tee at 3:35 which then dumps into the risers.
      At 5:04 there are two hoses that direct hot water from the open thermostat into the exhaust manifolds. If you are having an overheating problem it’s either the thermostat is not releasing engine water to these two hoses or the flow through these hoses is restricted by partially clogged exhaust manifolds. One trick I’ve seen is to use clear hose pieces at these two hose outlets to visually see how much water is flowing.

    • @TaylorTaylor-yi4qd
      @TaylorTaylor-yi4qd 2 роки тому

      @@moccasinmarine I’m going to try that. I really appreciate your help. I live in Griffin, Ga. Do you work on boats or just rebuild the engines for them? Thank you again for your help!

    • @moccasinmarine
      @moccasinmarine  2 роки тому +1

      I primarily rebuild boat engines. I do outdrive work only if it is in support of prepping the boat to get it back to water ready.

  • @danielbodurian9612
    @danielbodurian9612 Рік тому

    Good video. Just don't trust that single point drain for winterization though. In addition, You have to open the blue drain plugs (between 5-7 of them) and stick a tie rap into the holes to un-crust the rust so that the water will flow freely. Then you need to get MARINE antifreeze (not the pink stuff) into the block. Now some guys use the muffs to do this others disconnect the hoses on the front of the engine thermostat and pour it in there. Its up to you. Also, there is alot of debate as to whether leave the antifreeze in or drain it. Again, do your research. I prefer to leave it in because it has corrosion inhibitors built in that will help prevent issues over the cold winter months. Also, if you live in Florida or have an outboard consider yourself very lucky because you can ignore all this!

  • @juhavehnia7862
    @juhavehnia7862 9 місяців тому

    Great video! Some of this stuff is really hard to see while the engine is installed.

  • @juvehill
    @juvehill Рік тому

    also does water go through manifold through top riser hose as well? and leave the manifold drain? if not then i dont see how the manifold can ever be flushed with fresh water through muffs ect..

  • @juvehill
    @juvehill Рік тому

    question.. if i connect a garden hose right to the fitting a bottom of exhaust manifold , how much water should come out elbows or risers, im trying to check flow through manifolds but when i connect to bottom of each there is just back pressure (if drain is plugged ect. )

  • @carmencordero2779
    @carmencordero2779 Рік тому

    Another great video can i convert my single point system to a regular kind to simplify the system to many hoses for little gain.

    • @moccasinmarine
      @moccasinmarine  Рік тому

      Not only can you but you should. Single point drain systems get clogged up with debris from rust so you really don’t know if it’s drained or not. If each drain port is manually drained by you then you know the drain was successful and you didn’t leave water in your block.

  • @cecilhillier2007
    @cecilhillier2007 2 роки тому

    Great Video, thank you for doing this, at 4:32 you show the Y fitting that feeds the main engine water pump, is the other part of the Y fitting also filled with water feeding the thermostat housing (thermostat closed) does this water entering the thermostat housing flow out to cool the exhaust manifolds. Am I understanding correctly that when the engine is running, the engine water pump is always flowing through those two holes and returning through the block drains, then when the thermostat opens we get water flowing through the block and engine head returning through the thermostat housing and back through the Y fitting to mix with other raw water to feed the engine pump again.

    • @moccasinmarine
      @moccasinmarine  2 роки тому

      Watch the video at the 4:48 mark and take a screen clip for purposes of this discussion. The large hose on the left is the engine return back to the water pump. On the right opposite the large hose you’ll notice there is no other large hose. If this were a normal open cooling system your incoming raw (river, ocean, etc) would connect here and act as the fill and cooling water source. But this being a single point drain the incoming raw water comes into the engine return at the “Y” you referred to at 4:32. Your understanding of the flow is incorrect. The engine loop when cold is water enters at the bottom of the Y just mentioned. This is only on initial fill. If the engine has run prior, the loop is out of the engine underneath the thermostat and through the large hose on the thermostat housing back to the pump. It enters the engine at the front two holes and leaves at the thermostat housing completing the loop. When it gets warm the thermostat opens and dumps water to the exhaust manifolds on both sides at the lower hose connections. New raw water enters because the thermostat dumped water. This is the engine cooling cycle.
      But in order to keep raw water flowing to cool the power steering fluid and gasoline raw water flows from below to the tee at the 3:36 mark. This tee routes water to the upper exhaust connections. Water always flows through these hoses to cool the fuel even if the engine is cold.
      With this new information I recommend you watch the video again because I did discuss these flow paths but I understand that I may not have made it clear.

    • @cecilhillier2007
      @cecilhillier2007 2 роки тому

      @@moccasinmarine I will watch it again to better understand, thanks.

    • @moccasinmarine
      @moccasinmarine  2 роки тому

      @@cecilhillier2007 don’t take my reply as criticism. Explaining things in comments and videos, esp without a rehearsed and researched script, is bound to cause confusion and lack clarity. Hopefully through a discussion we can sort it out.

    • @cecilhillier2007
      @cecilhillier2007 2 роки тому

      @@moccasinmarine I appreciate you setting me straight, I watched your video again and again in conjunction with your latest comments, I also had a closer look at the thermostat housing flow paths, I now fully understand how my cooling system works, you're providing a great service to people such as myself, thanks again.

    • @moccasinmarine
      @moccasinmarine  2 роки тому

      @@cecilhillier2007 I’m soon going to do a video on closed cooling system for boats and I am going to try and design a closed cooling system for the same that’s less expensive than what’s out there now.

  • @cavalrylogisticsllc1233
    @cavalrylogisticsllc1233 7 місяців тому

    hi the hose that's on bottom of raw water pump what its for. Thanks

    • @moccasinmarine
      @moccasinmarine  7 місяців тому

      What is the time in the video that you asking about?

  • @Kiikonic
    @Kiikonic Рік тому

    Hello,how are you, thank you for video extremely helpful.
    But I need a help, instead of a handle I have a long rubber tiny tube/pipe attached on the top of water distributor housing,and I can not understand is that for draining? Because this tube was placed all the way up and thrown on top of my engine and on another engine it's just hanging down from distributor housing.
    If you can please explain point of that rubber tube and how to properly place it😊 mercruiser 6.2 horizon
    Thank you again

    • @moccasinmarine
      @moccasinmarine  Рік тому

      I would need a photo to help. Email photos to moccasin.marine.llc@gmail.com

    • @neilgwaltney2822
      @neilgwaltney2822 Рік тому

      @@moccasinmarine I've spent two days tracking down part information for the water distribution housing because the mechanics around me didn't know what it was. This was a very informative video of the coolant system. The model you are speaking is the air actuated system instead of the rod actuated or the manual drain shown in this video. There are four part numbers depending on which system is used. The actually functionality of the water distribution housing never changes, only the the method of draining the water out of the system. Your system with the small hose on top is just a vent and two hoses out of the side is the air actuated system. You can see the small air lines at the top of the motor where you connect a small air pump (basically a bicycle tire or hand held pump) to the right side of the system and add air until the valves turn green, then open the valve next to it by pulling up. They have a manual if you google search it, here is the link (chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/f01.justanswer.com/oldnewenglandmarine/288af04e-f0bb-4404-b31c-ba57ccd041a8_mercdrain.pdf)
      This then drains water out of the bottom of the water distribution housing without having to manually pull the plugs. Here is a link to the parts breakdown of the system www.hardin-marine.com/s-2843-water-distribution-housing.aspx. The manual housing is $30 on Amazon or E-bay, but parts range to over $500 depending on where you go for the rod or air actuated versions.
      Not a lot of info out there for this, thanks again for posting the video. Wish I found this before spending hours researching and pulling the housing unit out.

  • @raulfernandez9111
    @raulfernandez9111 2 роки тому

    Does the exhaust manifold check valve come apart? I can see in the parts diagram that you can buy an oring and a little ball that go inside. Does it just twist open?

    • @moccasinmarine
      @moccasinmarine  2 роки тому

      I don’t know the answer to that question. I also don’t currently have any boats in the shop I can look at to find the answer.

  • @billybolt31
    @billybolt31 Рік тому

    how do you remove the fuel cooler on these engines? Thank You for the videos

    • @moccasinmarine
      @moccasinmarine  Рік тому

      You disconnect the fuel lines from the fuel water separator and the fuel rails. Then unbolt the cool fuel bracket from engine mount and pull fuel pump assembly out. Once it’s out you can disassemble the parts.
      ua-cam.com/video/XFt7h3Mzkzo/v-deo.htmlsi=mi5VrV47sHL1lxgU

  • @beaverml3376
    @beaverml3376 3 місяці тому

    I got the same system on my boat I have a question about the way to fill the block and the manifolds. Right next to the thermometer off to the right is a bolt kinda of on a angle a bit could that be removed and filled with coolant and it would fill the block and manifold?

    • @moccasinmarine
      @moccasinmarine  3 місяці тому

      This is an open system. It fills up with raw water automatically once the drive is turning. You can’t and SHOULD not attempt to put coolant in this system. All the coolant will come out on the ground in less than 2 minutes.

    • @beaverml3376
      @beaverml3376 3 місяці тому

      Antifreeze for winter I have to run it though the system 100%

    • @beaverml3376
      @beaverml3376 3 місяці тому

      ua-cam.com/video/LboIjbWTRTc/v-deo.htmlsi=oyJGwj7yTzwHYYuR

    • @beaverml3376
      @beaverml3376 3 місяці тому

      Around the 30 min mark

    • @beaverml3376
      @beaverml3376 3 місяці тому

      ua-cam.com/video/LboIjbWTRTc/v-deo.htmlsi=u7f7CHyeqpur_dO9

  • @donschlegel1972
    @donschlegel1972 2 роки тому

    Thank you very much for explaining that I appreciate it I have the same engine and my water distribution housing is leaking is that not that’s not normal right appreciate any help thank you

    • @moccasinmarine
      @moccasinmarine  2 роки тому

      No water leaks are normal. You should find the source of the leak and tighten a clamp or replace the hose or leaking part.

  • @hookedonboating4750
    @hookedonboating4750 3 роки тому

    Do the small hoses that run from the block to the drain manifold also have quick connects at the manifold like they do at the engine block connections?

    • @moccasinmarine
      @moccasinmarine  3 роки тому +1

      Good question which I don’t know the answer to yet. I don’t think they do from memory but I’ll find out this week because I’ll be assembling this engine/ system this week. I’ll post back with an answer.

    • @hookedonboating4750
      @hookedonboating4750 3 роки тому

      @@moccasinmarine Thanks