Converting from raw water to closed

[bijou22]

Details: VP 4.3GL 1997, Cobra SX leg.
I work as an engineer for a heat exchange automotive company and was wondering if anyone has experience in changing their boat from raw water only to closed circuit engine, raw water cooled.
I guess you would still need to have the raw water coming in to cool the fresh water via a heat exchanger.
I have access to all this equipment but was looking to interact with someone who knows more about it or has any kind of experience.

 

[mkast]

Re: Converting from raw water to closed

If you look in the Mercruiser service manual, both systems are covered. You can see all the items needed to do the conversion.

 

[mkast]

Re: Converting from raw water to closed

If you look in the Mercruiser service manual, specific to your engine, both systems are covered. You can see all the items needed to do the conversion.

 

[bijou22]

Re: Converting from raw water to closed

Where can I find this online to view?
The boat is permanent saltwater moored, do you agree that its an essential upgrade, either that or a Perko flush valve, which I have, but would rather look at conversion instead.

 

[imported_Seatrek]

Re: Converting from raw water to closed

Details: VP 4.3GL 1997, Cobra SX leg.
I work as an engineer for a heat exchange automotive company and was wondering if anyone has experience in changing their boat from raw water only to closed circuit engine, raw water cooled.
I guess you would still need to have the raw water coming in to cool the fresh water via a heat exchanger.
I have access to all this equipment but was looking to interact with someone who knows more about it or has any kind of experience.

I recently converted my 2001 5.0 G.I. Volvo Penta to a closed system. After doing a ton of research on the subject, I purchased the complete kit from San Juan Engineering. Think it was around $625.00. Took about 3 hours to install it. You get all the parts needed for the installation and instructions that are well written and easy to follow. IMHO, a clean install, quality as good or better than the OEM closed cooling systems offered and much much less expensive.8)

 

[KaGee]

Re: Converting from raw water to closed

A closed system is a must in salt water. I know you say you work for a company where you can get parts, but a kit might be a better idea.

How long has the engine ran in saltwater as an open system?

 

[bijou22]

Re: Converting from raw water to closed

Boat has run in saltwater for around 18 months now. I do however drain the engine block after each trip but this is getting to be a bit of a nuisance.
I am guessing that the raw water intake remains, and cools the tap water through a heat exchanger?
Do you have an expansion tank also to fill?

 

[Don S]

Re: Converting from raw water to closed

Manufacturers do not recommend converting after 125 hours. The biggest problem i have found it the heat exchangers plug up from the rust and scale inside the block coming loose and plugging the new HE. The problem is, is that it's on the side that can't be cleaned out and you end up replacing your new Heat Exchanger again.
You have already stated you drain the block all the time, but that is worse than leaving the water in the block. It's covered with salt and allowed to dry.
Had you been flushing with fresh water or even better something like Salt-Away it would have been better.
I have installed systems on older engines, and have had about 50% failure rate.

Since you have a Volvo, you might want to get a Volvo manual, not a Mercruiser manual.

Here is a picture of a typical Volvo 4.3 closed cooling system. that will give you an idea what what has to hook to what. You would also need a different thermostat housing and thermostat.

 

[bijou22]

Re: Converting from raw water to closed

Thanks Don, as always a wealth of knowledge, but what would you do in this situation, the boat is in the marina for most of the year.
I have a Perko flush valve and was considering fitting this?
I do not know of any other way apart from conversion. The boat has done 35 hours when I bought her and around 15 since, low I know, but I know the history.

 

[Don S]

Re: Converting from raw water to closed

People run raw water cooled engines in salt water all the time, but they don't drain the block each time. If you leave the water in it, at least it displaces the air which is the major cause of the rust and scale. You can also get a Neutra Salt kit from Volvo. I'll get a link for you, right now their site is down.

 

[Don S]

Re: Converting from raw water to closed

Here's the link:
http://www.qlmarine.com/ql.asp

Click on "Products" at the top, then choose Neutra Salt from the left hand nav bar.

 

[bruceb58]

Re: Converting from raw water to closed

I have been looking into this myself for my 7.4L Volvo which has 180 hours on it of which 100 hours is salt use.

Found that the only one available for mine was from San Juan. I spoke with an engineer there yesterday and told me that there have been people that have put their systems on engines with 400 salt hours on them and worked out ok. I am sure it depends on how the engine was flushed. I have heard the same thing that Dons said in that it is better to leave the block full of salt water than to drain it. Less oxygen to promote corrosion with full water jackets.

My big worry is the salt embedded in the pores of the block. I have read that it is important to run the engine on distilled water the first year and keep an eye on it and drain it frequently. When you start using antifreeze, it is important to use low silicate level antifreeze.

I have found the best prices for the San Juan systems at Ocean East Marine.

 

[bijou22]

Re: Converting from raw water to closed

Thanks guys, but do you have any comments on just fitting a Perko flush valve instead?
Would this do the job?

 

[Don S]

Re: Converting from raw water to closed

Hook it up like the instructions say. It'll work, but it really won't neutralize the salt, just flush MOST of it away.

 

[paulie0735]

Re: Converting from raw water to closed

With only 50 hours on the engine I would do the conversion. The kit is the easiest option but if you have the skills and the tools than making your own plumbing may be an option for you. I would get the heat exchanger chemically cleaned after the first 50 hours or so to remove any scale that the coolant has dislodged, should be fine after that. I always recommend a separate oil cooler with any closed system, it will significantly reduce the load on the cooling system. There is specific coolant available for marine cooling systems. Good luck.

 

[bijou22]

Re: Converting from raw water to closed

The neutra salt idea looks simple enough to put together myself, I have all those parts to hand. My main worry is that it does not cut off the flow of raw water into the system when flushing, this seems a little strange. At lease the PERKO valve does this at a quarter of the cost and provides clean fresh water which you can run for 15 mins at no cost. Is the neutra salt system simply an overkill method, especially the amount they are charging for such a simple piece of kit?

 

[Don S]

Re: Converting from raw water to closed

The neutra salt idea looks simple enough to put together myself, I have all those parts to hand. My main worry is that it does not cut off the flow of raw water into the system when flushing, this seems a little strange.

It sounds to me like you don't know how the Neutra-Salt system works. There is nothing in that system that could possibly block off the cooling water.
All it is is a small reservoir similar to a cooling system overflow tank. in the hose from this reservoir to the TEE fitting in the intake hose on the raw water pump is a small solenoid valve that when the engine is running (at idle) all you do is turn it on and it meters the correct amount of Neutra-Salt concentrate into the system which neutralizes the salt. You could also run Salt-Away in it as it does the same thing, just an easier and cheaper product to buy.

 

[bijou22]

Re: Converting from raw water to closed

Cheers guys for all your advice and help, can I also just fit the Perko valve and have a bucket of salt-away nearby and then suck it up from the bucket through the engine?

 

[seatek]

Re: Converting from raw water to closed

Cheer guys for all your advice and help, can I also just fit the Perko valve and have a bucket of salt-away nearby and then suck it up from the bucket through the engine?

BTW, It's spelt "Cheers" and people in Wales never say that word anyway.........
It's come to mind the question of why you seem to be so cheap.
Don and others have posted most all of the pertinent information from people who have learned from experience and yet you seem now to ask questions about buckets.


"There's a hole in my bucket dear liza, dear liza"

I don't eat Spam or trolls, but I can sure smell them......zzz
..Then again it could just be another silly question....

 

[bijou22]

Re: Converting from raw water to closed

Hold on seatek, this forum is for discuusion as well as advice and I am quite entitled to put forward any ideas I may have on this subject. If you cannot say anything that is in anyway someting to do with the subject then please don't bother.
Further to this, we do say cheers in WALES - UK