How to winterize closed cooling system engine

[karlsonab]

Hello,

I would like to winterize 7.4 L Mercruiser engine (1997 Mercruiser 7.4 L 8 cylinder) with closed cooling system.

By reading various threads on the forum, I would like to verify the process.

1. My plan is to add stabilizer to the fuel, run the engine, and change oil in it.
2. Since my engine has a closed cooling system, I will remove drain plugs on my engine, manifolds, water pump and heat exchanger and let the water drain.
3. I will connect the muffs and run anti-freeze thought it. I assume the purpose of it is to make sure the heat excahnger, etc will have the anti-freeze there over the winter.
4. I will close all the plugs removed in step 2.

If some one can please validate my understanding of winterizing closed cooling systen and make any recommendations, it would be greatly appreciated.

 

[Don S]

Re: How to winterize closed cooling system engine

You are missing a lot of things you should do, try this. http://forums.iboats.com/showthread.php?t=178695

2. Since my engine has a closed cooling system, I will remove drain plugs on my engine, manifolds, water pump and heat exchanger and let the water drain.

You only drain the raw water (that can freeze) side of the system, not the antifreeze side.

3. I will connect the muffs and run anti-freeze thought it. I assume the purpose of it is to make sure the heat excahnger, etc will have the anti-freeze there over the winter.
4. I will close all the plugs removed in step 2.

You can't run antifreeze through anything with the plugs out.


Do you have a full or half system? Full system cools exhaust manifolds with AF, half does not.

 

[HT32BSX115]

Re: How to winterize closed cooling system engine

Howdy,


I have a full closed 7.4L cooling system.

There's really not much to winterize.....(except the 18 items in the link above!!) The heat exchanger and risers drain from gravity (but remove the HE drain plug to check!!)

Raw water does pool in the connecting hoses from the raw water pump to the oil and power steering coolers though and you MUST ensure that they are absolutely clear of raw water, I have disconnected the raw-pump discharge and used a wet-or-dry VAC to suck all the water from there...........

or you can flush the entire raw water system with a suitable antifreeze.


If you decide to do that, you must fill the raw water lines from the drive to the pump (by pumping it with "muffs' etc and/or siphon). The Bravo raw water pump WILL NOT draw liquid from the drive to the raw water pump and you'll damage the impeller in mere minutes if you try.

If you have a "half" system, you must still drain the exhaust manifolds..... along with the above.....

Don't forget you should also change the drive oil, check the alignment etc too....


Regards,


Rick

 

[Bondo]

Re: How to winterize closed cooling system engine

Hello,

I would like to winterize 7.4 L Mercruiser engine (1997 Mercruiser 7.4 L 8 cylinder) with closed cooling system.

By reading various threads on the forum, I would like to verify the process.

1. My plan is to add stabilizer to the fuel, run the engine, and change oil in it.
2. Since my engine has a closed cooling system, I will remove drain plugs on my engine, manifolds, water pump and heat exchanger and let the water drain.
3. I will connect the muffs and run anti-freeze thought it. I assume the purpose of it is to make sure the heat excahnger, etc will have the anti-freeze there over the winter.
4. I will close all the plugs removed in step 2.

If some one can please validate my understanding of winterizing closed cooling systen and make any recommendations, it would be greatly appreciated.

Ayuh,.... Welcome Aboard,..... I just wanta add,...

You only drain the raw water (that can freeze) side of the system, not the antifreeze side.

Provided, of course, that the antifreeze side is to a sufficient solution, for temps below those expected, 'n not just slightly green water....