Converting to closed cooling system

[nofuss]

Hi all

With winter upon us, people like me have to read all the threads on winterizing and relate what we can to our situation. while u guys have fun actually winterizing

I am thinking of converting my 4.3 v6 merc engine that is always used in salt water, to closed cooling, however I remember being told that i run the risk of problems with the glycol in the antifreze coming into contact with the salt in the block.
now I dont need the antifreze properties but the anticorosive properties help in my area.
However when winter comes around every body with their raw salt water cooled engines full them up with anti freeze.
Could someone please advise me on how this works. because from what i see the engines are run with antifreze going in untill it shows at the exhaust.

is it that the glycol problem only occurs when the engine is run at operating temp.

my winterization question, please advise.

No Fuss

 

[HT32BSX115]

Re: Converting to closed cooling system

Howdy,

If you have an engine that has been used more than a year and/or about 100hrs in raw salt water, most people recommend that you do not install closed cooling.

The accumulated amount of rust already in the block cooling system can flake off and completely clog the heat exchanger to the point of failure.

It's a MUCH better choice to consider adding closed cooling on the next (new) engine


Cheers,


Rick

 

[Eric 3.7LX Alpha 1]

Re: Converting to closed cooling system

^^ 2nd that^^

 

[Fishermark]

Re: Converting to closed cooling system

^^3rd that ^^

I remember being told that i run the risk of problems with the glycol in the antifreze coming into contact with the salt in the block.

That's not the problem. As described above, the bigger problem is the block will continue to rust and flake due to the salt being absorbed (for the lack of a better description) into the iron. Those flakes will completely clog the heat exchanger.

You see the principle at work with anything iron you find while scuba diving - etc. You can take it out of the salt water and rinse it all you want - it will continue to rust and flake off.

 

[nofuss]

Re: Converting to closed cooling system

Thanks for the info guys, now i get the picture. thats one less project this time. a few more dollars in the savings account

No Fuss

 

[nofuss]

Re: Converting to closed cooling system

guy with this in mind would it be safe to say that it is not practical to buy a remanufactured engine, if you are running closed cooling as you would not know if it was used in salt water. or is there a way around that.

No Fuss

 

[HT32BSX115]

Re: Converting to closed cooling system

I'm not sure about that. I would ask if the block was replaced in the "re-manufacturing" process.

I wouldn't want a previously "salt" block either!

 

[magster65]

Re: Converting to closed cooling system

My neighbor has run his 5.7 powered boat in the salt for 15 years without a problem... replaced the risers once. We put a closed cooling system on it a year ago and it's been running perfectly ever since.

 

[nofuss]

Re: Converting to closed cooling system

magster65

Your experience seems to match with my presonal feeling however, since I have very little experience with inboard engines I have to ask the guys who have been around a while, and do my research.

My thinking is that if enough metal flakes off of the internal of the block to clog the heat exchanger in a short enough time to not be able to recognise a slow reduction in performance. then if the block is continued to be used in salt water, the same or a greater amount of metal would be breaking off of the block and so soon I will no longer have an engine block.

Did your neighbour do any thing special when he made the change over, and is he running regular glycol antifreze in the closed system.

I was actualy trying to design a filter with a hole size smaller than the tube size of the heat exchanger that would be able to collect particles smaler than what would be expected to block the heat exchanger, as a method to be able to use closed cooling on my engine.

any one ever heard of a filter being used to prevent this problem. or anyone else converted with out problems. I may be changing out one engine and If I do this I would want to go closed cooling. and would prefer to have both engines on the same system . other engine sems strong and in very good condition.

No Fuss

 

[Fishermark]

Re: Converting to closed cooling system

We're justing talking general rules of thumb... everyone's experience will be different. Every engine will have a different history of use and care. If you want to try it, go ahead. It might work out fine... or it might not. In the words of the famous Dirty Harry, "Do ya' feel lucky?"

 

[nofuss]

Re: Converting to closed cooling system

thanks for that. I have heard so many more opinions that speak against water cooling the old salt engine that I automatically accepted the opinion. however, with a problem that i could possibly filter out I think i would probably try it. If it fails I would just full the heat exchanger with oil and run the engine raw water cooled. would have the exchanger if the engine does die. but if the problem was the glycol thing that was more difficult to mitigate against i would be more concerned, as it might in the end be harder to convert back to raw cooling without problems.

 

[HT32BSX115]

Re: Converting to closed cooling system

Raw water cooled engines last for many years if taken care of properly.

There's little or no (financial) benefit in converting an older raw (salt) water cooled engine to closed cooling.............do you get freezing temps there?

If you do, just drain it before the cold arrives.

A good closed cooling system will cost about $800 USD and higher by the time you get it.

Here's where I got mine:: http://www.oceaneastmarine.com/


My (1997 model year) engine had 125 hours of (fresh-water only) operation on it when I installed the full-kit from the above retailer in 2005.

I had the engine on a stand when I removed all the core (soft) plugs and removed a lot of rust, sand, and other debris from the water jacket through extensive flushing.

If my engine had been operated in salt water I would have never attempted it.

It's a risk in either case. ......... even though I was able to remove pretty much all the loose rust and other debris, cast iron continues to slough-off rust inside the cooling system and manifolds.

It's not all that much in a fresh-water engine, but is considerably more in a salt water engine.

There is a greater risk of that rust (that does break loose) clogging the coolant side of the rather expensive heat exchanger. It's very hard (and sometimes impossible) to clean them out and you end up with an engine that runs hot or over heats (right where you don't want them to)


IMHO, it's more cost effective for you to just run your engine until it needs rebuilding. Then replace the block, manifolds etc... and add closed cooling then.



YMMV


Regards,


Rick

 

[Aloysius]

Re: Converting to closed cooling system

I've done it on my engines..Fords with maybe 20 yrs. of saltwater use.

First, flushed the poo out of the engines, then ran salt-away through them. Installed the heat exchangers, new thermostats, and antifreeze. Worked fine, but anti-freeze was getting contaminated.

Pulled the engines and rebuilt them last year. Completely disassembled the blocks, pressure cleaned the water passages. Jesus what a bunch of rust and junk I cleaned out. However, the coolant is clean now!

Caveat! Chevies tend to rust more than Fords...different cast iron. I rebuilt my salt water blocks because the cylinders and pistons were still servicible..NEVER waste money machining a salt water cooled block!

 

[magster65]

Re: Converting to closed cooling system

magster65

Your experience seems to match with my presonal feeling however, since I have very little experience with inboard engines I have to ask the guys who have been around a while, and do my research.


No Fuss

Always a good plan.
My neighbors boat is a 20 Monterey 5.7. They bought it new in '95 (I think it's a 95). They, on rare occasions take it lake boating but they spend almost all their time in the salt (they have oceanfront cabin... the lucky dogs!). He's not 100% diligent with the post salt flushing ritual but he does most of the time.
So when it came time to install the kit he flushed the motor the night before... gave it some revs but nothing special. We installed the kit and just ran water in it for the first trip out. He told me that a bit of rusty water came out but nothing too bad. He drained it and put in the green anti-freeze 50 / 50 I think) and that was it. No problems.
My thought is that if there's no issue before the kit goes on, there won't be after. I've installed 4 now and haven't had problems with any of them except 1 which was a temp sensor issue, not a heating or scale problem. This particular kit relocated the sensor to a manifold port and it was giving false readings... the cure was to modify the replacement t-stat housing to put it back there. I'm a firm believer in the fwc kit install.
Cheers

 

[redjmp]

Re: Converting to closed cooling system

Wow does it get cold enough to freeze in Trinidad?

If you are worried about scale and rust in your heat exchanger, try running a raw water strainer in front of it. Makes it easy to to keep an eye on things through the clear window and it easy to clean out...

http://www.foreandaftmarine.com/STRAINERSRAWWATER.htm

 

[telstar1]

Re: Converting to closed cooling system

The filter sounds good but it would have to be on the closed side of the cooling system to capture the scale. Not sure if plumbing that in would be practical.On my system(San Juan) there are 3 different circuits of coolant leaving and returning to h.e.-one to block and one to each manifold- I suppose you could plumb the filter into one of the circuits and it hope it gets the scale from all over based on the coolant getting pretty well stirred up by the circulating pump.

 

[Lou C]

Re: Converting to closed cooling system

I have asked mechanics here (salt water, probably not as salty as the Caribbean though) and most say put it on a new engine but older engine, not worth it. It will take a long time for an engine block to rust through, but that's by our standards where boats are in use only 1/2 of the year at most. The time that the boat is winterized I fill the engine and manifolds with -100 antifreeze and that seemed to cut down on corrosion. I have recently replaced the circulating pump (original) and thermostat (these get sticky in salt water and have to be replaced every 1-2 seasons) and have not seen any flaking rust in the thermo housing, intake manifold or cyl head cooling passages that I could see...

I'd run this one as long as you can and then if you repower, get a new engine new block n heads and then put closed cooling on that one...
That's what I'm doing when the time comes...

 

[JaseBosto]

Re: Converting to closed cooling system

Seems like a pointless waste of money to me....
Why change something that's been running fine....
Just sayin.

 

[magster65]

Re: Converting to closed cooling system

Seems like a pointless waste of money to me....
Why change something that's been running fine....
Just sayin.

Well... by that way of thinking, why upgrade anything then?
This is an easy mod that will add years to your boats engine. I think not doing the mod is a pointless waste of money.
Just sayin.

lol

 

[Lou C]

Re: Converting to closed cooling system

Well in freshwater I can see not adding it, but for an cast iron engine in salty Caribbean waters, (original poster's question) of course if starting with a new engine, it's worth it. Those boats are used in salty water and used all the time. Here we are in salt but the boat is stored half the year. Big difference in operating conditions.