Closed cooling system

[dozerII]

Mercruiser 1976 120. I live in the north and boat in fairly cold water for most of the year. In late August the water will warm up to 70, but for the most part it would be 50 on average and all fresh water. I am looking at putting on a closed half system to get better and more consistent operating temps, plus easier winterizing, allowing me to go out later in the year. Plus less corrosion in the block due to running antifreeze.
Questions are:
Is it worth it to do it?
What is the best system out there?
Pros and Cons?

All Opinions appreciated.

 

[Bondo]

Re: Closed cooling system

Mercruiser 1976 120. I live in the north and boat in fairly cold water for most of the year. In late August the water will warm up to 70, but for the most part it would be 50 on average and all fresh water. I am looking at putting on a closed half system to get better and more consistent operating temps, plus easier winterizing, allowing me to go out later in the year. Plus less corrosion in the block due to running antifreeze.
Questions are:
Is it worth it to do it?
What is the best system out there?
Pros and Cons?

All Opinions appreciated.

Nope,.... Not that I can see,....

The T-stat should hold the motor temp where it oughta be, not a heat exchanger,.....

It Won't make winterizin' Easier, as you've only got 3 drain points now, 'n ya still will have several drain points to tend too,...
A Drained block, 'n manifolds is already Winter Safe,...
Runnin' late in the season is already Easy, just Drain it at the launch on pull out,...

'n lastly, yer boatin' in sweetwater,.... Corrosion is at a minimum now,...
The block, 'n manifold will last 'bout 100 years, without antifreeze,....

 

[ziggy]

Re: Closed cooling system

All Opinions appreciated.

that's all i have for ya. an opinion. since i've never undertook what yer thinking about doing.

that said. everything i've ever read on iboats about doing this, is, that it may not be a good idea.
reason usually stated is that the rust scale (in the block and manifold) that's already in your open system, if ya go to closed, the rust scale already present could possibly plug up the water passages of the heat exchanger. that would stop the cooling process if they were plugged. i've read that enough times that i don't think i'd do it to my engine. +, i don't know about your engine. but 'every time' i drain my manifold, i always get rust scale out of it. in the fall, after a seasons worth of use, i can take the manifold drain plug out and there's always enough scale to prevent draining. i must probe the hole to get water to flow. if that were in a closed system. i'd think it'd be enough stoppage to prevent cooling.

if ya wanna have a freash water cooled engine. it should be from square one of the life of the engine.

that's my opinon.

lets see what others have to say now. maybe someone has done the conversion and will 'know' the answer your looking for. good luck in your decision.

 

[tpenfield]

Re: Closed cooling system

Mercruiser 1976 120. I live in the north and boat in fairly cold water . . . I am looking at putting on a closed half system to get better and more consistent operating temps, plus easier winterizing, allowing me to go out later in the year. Plus less corrosion in the block due to running antifreeze.
Questions are:
Is it worth it to do it?
What is the best system out there?
Pros and Cons?

All Opinions appreciated.

Just to add to what Bond-o said; the thermostat will give you a consistent engine operating temperature, regardless of the water temperature. (That's what thermostats do . . . :thumb: )

If you boat in salt water a closed cooling system is really worth it. If you boat in fresh water, not so much.

A Full system would be better than a 1/2 system as it would include the exhaust manifold in the closed system.

SeaKamp and San Juan Engineering (SJE) are the better after-market kits available. I have 2 SJE Full systems that I installed a year ago on some 7.4L engines that were going to be used in salt water, after having been used in fresh water for 16 years.

Just to comment on what ziggy stated . . . that would apply if the engine had seen salt water use previously as iron scale will be prevalent in the engine block. If the engine was used in fresh water, then a conversion during the engine's life should not present a problem. If desired, you can always flush the engine block prior to installation to remove any sediment, etc.

 

[dozerII]

Re: Closed cooling system

Thanks for the great advice guys, I will put the money I was going to spend on this toward the rebuild of the boat.