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Question

I have 2005(?) 8-cyl. Mercruiser, Model # MCM 350 MAG MPI, Engine serial # OW 326634. I wanted to winterize it and looking for advise how to drain it properly and fill in with antifreeze. Is there anything else I should do at this point? How about a bilge pump.. there is a water in it?

Submitted: 52 days and 6 hours ago.
Category: Boat
Value: $48
Status: CLOSED
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Optional Information

Make (of engine): MerCruiser
Model (of engine): MCM 350 MAG MPI
Year: 2005
Horsepower: 320

Already Tried:
I drained it (?) and tryed to fill antifreeze but liquid is runing out through big rubber hose.

Posted by Captain Dave 52 days and 6 hours ago.

Info Request

Hello. Is this an inboard or an inboard/outboard? What hose is antifreeze running out of - something you disconnected? Let me know what type of motor system this is and I can give you proper winterizing instructions - there is no need to drain anything. As for the bilge pump, there will not be water in it, so you don't need to worry about it.

52 days and 5 hours ago.

Reply

I think it is inboard/outboard(?). Engine is inside but trim is outside on the back. I didn't disconnect anything. When you lift a trim you can see a 4" or so rubber pipe. Theat's where the antifreeze is running out.

Posted by Captain Dave 52 days and 5 hours ago.

Answer

OK, you are seeing the exhaust - that is where it should come from. The basic idea is to introduce antifreeze (hopefully you are using the non-toxic type - pink) into the water intake (usually by using "bunny ears") and let it circulate through the motor and come out the exhaust. Once it does, any water in the system has been displaced and/or diluted by the antifreeze, and you are winterized. There is no need to drain anything. If you have any other water system, like a livewell or fresh water sink, you'll need to pump antifreeze through them as well.

Posted by Captain Dave 52 days and 5 hours ago.

Answer

Here is a list of tasks that should be performed to properly winterize your boat and systems:

 

1. Fill your fuel tank to minimize condensation and add the appropriate amount of a good fuel stabilizer like Stabil - be sure it's for ethanol if your gas contains ethanol. Change your fuel filter if it hasn't been changed recently. Do this first so when you run the engine the stabilizer will get into the entire fuel system.

 

2. If you have a closed cooling system, drain it and replace with a 50% mixture of water and antifreeze. Don't use more than 50% antifreeze, since this will decrease the ability of the system to cool the motor. My suggestion is to mix your own and not to buy the pre-mix - mixing your own is a lot cheaper.

3. Warm up the engine so the thermostat is open. Disconnect the engine suction hose from the raw water intake. Place the end of the disconnected hose into a container of non-toxic antifreeze (the "pink stuff"). Now start the engine and let it run a few seconds until antifreeze comes out the exhaust. Alternately, you can use "bunny ears" and rig a hose to a container of antifreeze to accomplish the same thing. You can actually buy a kit for this at marine stores like West Marine or Boaters World (here is a link: http://www.mysimon.com/9015-11031_8-34208413.html .

 

4. Optionally use fogging oil to help coat the interior of the engine. If used, spray it into the air intake just as the antifreeze starts to appear at the exhaust in the previous step 3. This should stall the engine, otherwise shut it off. However, don't use the fogging oil if your engine is EFI, since that will foul your sensors. Some owners also remove the spark plugs and spray fogging oil into each cylinder, then replace the plugs.

5. While the engine is warm (not hot), change the engine oil and filter. If you leave old oil in the motor, the contaminants will tend to corrode the internal parts while in storage.

6. Spray a light coating of WD-40 (or similar) on the alternator and starter motor. Try to avoid getting the spray on the belts. Also spray linkages and cables.

 

7. Cover your air inlets, breathers, exhaust and fuel tank vents.

 

8. If you have a fresh water system, livewell, etc. run all the water out of the system, then disconnect the inbound hoses to the pumps, run a hose from the pump to a container of non-toxic antifreeze, then turn the pump on until antifreeze run out. Don't forget to replace any lines you removed. For the fresh water system, the antifreeze can be added directly to the water tank. Be sure to drain and bypass the hot water heater if you have one, otherwise you'll need 6 gallons of antifreeze just for that.

 

9. Remove the batteries and store them in a protected warm area, such as a garage or basement. This is a good time to check the water levels if they are wet cell type and fill them with distilled water if low. Don't worry about charging them now, but put them on a charger a week or two before you are ready to go in the spring.ing either a hydrometer or an open circuit voltage test (12.6 volts or higher).


10. Drain and replace the gear oil from your outdrive. Be sure to fill from the bottom until oil comes out the top hole so there are no air pockets.

 

11. Grease any grease fittings on the outdrive. Cover the prop and shaft so water doesn't get into the shaft area.

 

12. Some owners remove the props and send them out for reconditioning if necessary. You should at least carefully examin the prop(s) for damage and remove any foreign material from the prop, hub, etc.

 

52 days and 5 hours ago.

Reply

I know what "bunny ears" is, but can you be more specific how to use it. That is designed to go with garden hose, right? Also, in my manual it says that I should fill block with antifreeze. It's hard to ignore it. Antifreeze contains a rust inhibitor, that's important too.

Posted by Captain Dave 52 days and 5 hours ago.

Answer

Yes, you are right - that's what I am telling you how to do. When you run antifreeze into the motor (either using bunny ears or by disconnecting the hose and suctioning in the antifreeze) it runs through the entire engine block and out the exhaust. Although the water intake is on the outdrive, the water (or antifreeze) actually travels to the front of the engine and in, past the thermostat, and circulates through the block before exiting into the exhaust manifolds and finally out the exhaust. In normal operation the exhaust comes out underwater, which eliminates the need for a muffler. If you don't circulate antifreeze through the block, the block will crack if it freezes due to untreated water expanding, so your manual is absolutely correct.

 

There are winterizing kits sold in marine stores and online that have a tank to hold the antifreeze and a hose. You simply connect the hose to the bunny ears and start the motor. You can also rig up the same thing - you just need to get antifreeze to the intake.

52 days and 5 hours ago.

Reply

I disconected the hose at thermostat and put one gallon of antifreeze before it started to run out. Is my block full of antifreeze? It doesn't feel like. I have to leave and be back in half an hour. Thank you for your help so far.

Posted by Captain Dave 52 days and 4 hours ago.

Answer

I would run more than one gallon in - I use 4-5 gallons in each of my 350 motors. If the antifreeze coming out the exhaust is the same color as that going in, then it's full.

52 days and 4 hours ago.

Reply

If the same amount of water is coming in and out that is flushing not filling. What is a capacity of cooling system in 8-cyl. engine - 1gal!? There is no antifreeze in thermostat, I can see that. I agree that after runing 4 gal and when the color is the same before and after, there is no water any more, but is that full? Am I missing something?

Accepted Answer

Well, it really doesn't need to be full - it just need to displace or dilute most of the water so that whatever is in there will not freeze. If you use antifreeze that protects to -50 then even if only half of the water is displaced, it will be well protected. It is done this way to tens of thousands of boats and it works - in my opinion better than draining, which can sometimes leave some water laying in the block. I don't know the capacity of the block, but I'd guess a gallon or two would be it - the rest is hoses and the exhaust. You'll never see anything at the thermostat unless the engine is running and actively pumping water (or antifreeze) because gravity will alway partially drain the cooling system.

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Expert: Captain Dave
Pos. Feedback: 98.5 %
Accepts: 
Answered: 10/1/2009

Marine Mechanic

USCG Licensed Captain, 20+ Years Boating, Fishing, Maintenance and Repair Experience

52 days and 4 hours ago.

Reply

OK now we are on the same page. I understand that I am save with freezing but how about corrosion? My manual says - " for assurance against freezing and corrosion, fill antifreeze until block and head are full". Looks like we are ignoring that part, but that was my main concern.

Posted by Captain Dave 52 days and 4 hours ago.

Answer

For all practical purposes they are full, and at the very least all the surfaces have been coated with antifreeze and so they should be protected, although honestly I don't see that as much of an issue. I think you will be as protected as possible.

52 days and 4 hours ago.

Reply

Thank you, I am accepting your answers.

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