Replacing raw water system for heat exchanger in a 5.8l Ford OMC

[fgardinier]

I am finishing up the rebuild of my 1991 5.8l Ford/OMC engine from a Chris Craft 230 Cuddy Cruiser. The engine only has 225 hrs on it but all salt water. The block was cooked and checked for cracks, cylinders honed, new bearings throughout, heads were cleaned, valves and seats replaced and reground at a marine machine shop. Everything I could glass bead blast and repaint was done. I had the water pump and alternator rebuilt. I replaced all the bolts that were not in good shape and cleaned/painted everything. Originally I had intended to replace the exhaust manifold and risers and just run raw water thru the system again. However I was contemplating going to a heat exchange system later but have recently thought that now would be the best time for that, before exposing the engine to salt water again. I just read a post that said this is not a good idea and manufactures do not recommend this. With all the work that has been done does this still hold for my engine. Or is it a case where I am just wasting my money. Any advice on what I can do to increase my chances for success with a heat exchange system?

 

[Boats-A-lots]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

Hum... Wonder why they are saying it's not a good idea. I have had a heat exchanger (with antifreeze in it) since 1995 in my 4.3 Cobra. I mainly use it in salt water, I like the fact no salt water in the block, and my wife really likes the heaters when crabbing on a cold winters day. I could take some pics of it and post if you want to see the system I have.

 

[bruceb58]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

A block with that many hours in salt water is not recommended to switch to closed cooling. I was considering the same thing on an engine with only 70 hours on it and was talked out of it by San Juan Engineering.

 

[Boats-A-lots]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

Did they give you an explanation why? (just trying to make sense of it)

http://www.perfprotech.com/store/articles/fresh-water-cooling-benefits.aspx

 

[bruceb58]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

Said that I would be consantly cleaning scale and a gummy mess from the salt and scale that had leeched into the block reacting with the anti freeze.

 

[Boats-A-lots]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

Anticorrosion additives, changing the antifreeze once a year, flushing out the block, I would do what ever needed to done. In my case, the benefits (and peace of mind) far out weigh any additional maintenance I would have to do. I have never had any problems like that with mine. (knock on wood). And the heater and defroster from the exchanger come in really handy in the winter months crabbing. Salt water and engine blocks don't mix too well.

 

[Scott Danforth]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

if the block was baked during the rebuild, it will be as new as you can get a re-build.

I would put a HX on it in this case.

I myself am moving back to Florida, and before my motor hits the water down there, I will be installing a full system so all I have to deal with are risers.

 

[fgardinier]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

I think it was Don S. that said he had only a 50% sucess rate when converting an engine over 1yr old that was used in salt water. I was planning on running the engine on a stand. I could start cleaning the block with cleaners and an auto radiator. Owning an auto shop has its advantages. How mush time was on your engine when you converted and what did you do to help with the corrosion removal just after/before.

 

[Boats-A-lots]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

Um, yeah.. that would be awesome to own a auto shop. (I'm jealous). I have to work on my stuff in a half garage.. and most the time freezing. (no heat in there). Mine was used in fresh and salt water for 5 years before the install. Seriously, there have been no build up or scale anywhere. (and I'm real anal about the boat.. my car my go to hell, but I keep my boat up nice)

I have been trying to understand why there would be a reaction (science is so cool to me) and even been looking it up on line here since you started this thread. I have learned nothing about the why yet.. or how. You could always just run water with "water wetter" in it for the first couple of times. Water is a better cooler anyway then antifreeze. I use "water wetter" in my 454 GMC dually truck. I pull a 15,000 pound 5th wheel and it took 10 degrees off the engine temp.

 

[Scott Danforth]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

your first post you state the block was cooked. normally this is a high temp oven process followed by a blasting process.

if this was done, there is no need to "clean the block with cleaners"

 

[bruceb58]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

Before you do it, call up San Juan Engineering and get their advice. They would be more than happy to sell you their system. I was about ready to do it until they talked me out of it.

You also talk about doing a full system which includes manifolds. Many aftermarket systems do not include manifolds because it needs a bigger heat exchanger. i would go with a full system if possible. Just have to make sure you have enough room. In my case, because I boat in areas that have over 80? water, the size of the heat exchanger was an issue.

 

[Boats-A-lots]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

Bruce, could you show, send or post a website reading the dangers of this, and its reaction? I can find nothing on it. It's hard to believe if it were bad as one shop claims, that there isn't any info on the net about it. (backed by science and not some ones theory) I can not say how many hours I used mine in salt for 5 years before the install, but about 10 crabbing trips a year at least.

 

[bruceb58]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

A sales/engineer guy at San Juan Engineering told me this. I didn't get the info from a website. I was disappointed that I wsn't going to be able to do it. He was very adamant not to do it. My engine had 70 hours in only salt water.

 

[Boats-A-lots]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

Some antifreeze has liquid glass in it. Liquid glass is in fact salt that has been boiled. http://www.ehow.com/about_6376297_sodium-silicate-engine.html . It helps seal small leaks in the system. Most over the counter products you add to your cooling system contains salt, and it reads on the label to add to your cooling system. If it were harmful, I don't think they would have remained in Business. Really, I"m not trying to destroy this guys boat motor, and it didn't mine. Had I not done this to mine, I wouldn't be able to say... but I can say I did it to mine, and there has been no side effects at all.

 

[bruceb58]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

If his block was really put in a boil tank, i would be less hesitant to do it. Its the best thing you can do for a boat motor that is going to be run in salt water. If I ever need to replace my block, it will be the first thing I do.

I use the Volvo Neutra salt system currently on my boat for the second best option.

I would definitely run with just water for awhile before I put anti-freeze in it. Just be careful of freezing conditions, something I never have to worry about that goodness.

 

[Boats-A-lots]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

Yeah, and lucky him he has an auto shop to do it in. Could also use antifreeze that has sodium in it, that way there couldn't be an reaction.

As far as engines over heating on a freshwater system, I wonder about water wetter. I have not used it in my boat, but I do my GMC truck. Not sure what that has in it, never read the contents. But I know it works to help cool an engine. http://www.redlineoil.com/Products.aspx?pcid=10 My boat motor has never over heated on this system, so I never felt the need to put it in my boat.

 

[bruceb58]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

Water actually has a higher heat capacity that a 50/50 antifreeze mixture. Its drawback is that it has a lower boiling point than anti-freeze and lacks water pump lubricants(at least for automotive water pumps).

I have a feeling waterwetter is just a corrosion inhibitor allowing you to use straight water but would be interested in seeing its MFSD to see what's in it.

 

[Scott Danforth]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

water wetter is simply a surficant. no different than a few drops of dish soap (just without the bubbles). after 3 days of chassis dyno runs on a project for DOD / TACOM looking to get to 125 degree LAT at 100% load, I have tried everything. Water Wetter does NOT do anything at any concentration. if you question my testing, it was a NIST traceable lab used for validation of cooling systems and emissions and we had 3 vehicles being tested.

50/50 glycol mix transfers about 8% less heat than straight water. Straight glycol is much less. the 50/50 point is the best compromise between freeze protection and heat transfer (coolant properties). glycol also works well as a rust inhibitor and lubricant.

 

[Boats-A-lots]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

water wetter is simply a surficant. no different than a few drops of dish soap (just without the bubbles). after 3 days of chassis dyno runs on a project for DOD / TACOM looking to get to 125 degree LAT at 100% load, I have tried everything. Water Wetter does NOT do anything at any concentration. if you question my testing, it was a NIST traceable lab used for validation of cooling systems and emissions and we had 3 vehicles being tested.

50/50 glycol mix transfers about 8% less heat than straight water. Straight glycol is much less. the 50/50 point is the best compromise between freeze protection and heat transfer (coolant properties). glycol also works well as a rust inhibitor and lubricant.

I don't question your testing, but I know in my GMC, and my neighbors Dodge it took off 10 degrees from the block temp. We both pull heavy 5th wheels, and pulling large hills in our area in the summer block temps were almost in the red. Not anymore. (kind of off subject from what the OP is asking though) I have not used it in my boat. My temp has always been in the green. I mentioned it because I was wondering if converting to a closed system, the fear was over heating the block on the boat motor.

 

[talon8]

Re: Replacing raw water system for heat exchanger in a 5.8l Ford OMC

I concur with what Scott said about the cooling efficiency water verses 50/50 mix based on industry best practices. One also has to consider that heat exchangers are not 100% efficient so you have to take both effeciency losses into account when sizing a HEX system. If your primary cooling water supply is just enough for a normal or heavy load, you could run into over heating problems with a HEX system unless you increase your primary supply volume. This can be done by going to a larger seawater pump. The volume of primary cooling water can also be increased somewhat by abandoning the sterndrive water pick up and installing a through hull water pick up and larger hoses. This eliminates a long suction path and many bends, both of which work against you.