Convert from RWC to FWC??

[dpvandy01]

How costly of a job is this? Is it even possible? Would you do it?
Has anyone done it?
'01 280DA 7.4L BIII single. Plenty of room in the engine compartment.

 

[Sundancer]

It's worth it if you boat in salt water and have less than 150 salt water hours on your engine OR have less than 250 freshwater hours on your engine. It keeps the salt water from your block and makes the winterization a little easier. If you attempt to do it past the 150 hour mark in salt water, the ethylene glycol combines with the leftover salt and forms a gell like substance that impedes cooling from what I understand.

I'd love to have it on our boats, but both have surpassed the 250 mark. The cost of the kits can range from $700 to $1100 depending on brand, options and engine size. It's a fairly easy DIY installation if you can turn a wrench. The kits contain all the parts and brackets to bolt it up along with the hoses you'll need and instructions to guide you through the process.

 

[comsnark]

I heard the same advice regarding retrofits -> but not for the same reasons.

I suspect the "residual salt" issue mentioned above is a bit of a red herring. Shouldn't a fluid change out clear that up?

 

[fwebster]

I'm not buying the salt residue theory....it is quite easy to chemically neutralize any salt remaining in the engine. I also think you could retrofit a freshwater engine at any time with no ill effects.

After a boat has been run in salt water a while the cooling passages begin to fill up with ferrous oxide or rust sediment. It flakes off the inside of the cast iron cooling passages when the engine heat up and cool off repeatedly as it is used. Te sediment settles in the bottom of the passages along the block skirt and it will not come loose even if the engine is vatted during a re-build. After the sediment begins to collect, the damage to the block is done and a FWC retro fit won't fix or remove it. At that point, you are just as well off to save the $2500 or so it takes to add FWC and just repower when the engine will no longer run cool.......and that is what happens. The block skirt fillts with sediment and water will not circulate and the engine will begin to run hot. How long that takes also depends on lots of variables like salinity, hours of use, frequency of use, flushing or not, etc. Our old 390EC had sea water cooled 7.4's and we got 700 hours and 9 years out of them in a Gulf coast enviornment with regular and routine use and I flushed the engine with fresh water before leaving the boat.

One thing I do like about FWC engines is that it is much easier to maintain proper operating temperatures and that is critical with today's technology and EFI motors.

The cost varies by engine type, model and configuration. Is it worthwhile? On an '01 with several hundred hours in salt water for example, probably not. If the boat were a year or so old and had fewer hours it would be. Where that go or no-go point is depends upon a ton of variables.

 

[Nehalennia]

I will be adding FWC on a 5.7EFI with 94 hours on it and maybe(at the most I'm told) 10 in Saltwater. I will be adding the San Juan engineering kit

 

[Sundancer]

My understanding of the salt issue was gained from another website via George Van Parry. His explanation was that the iron block is porous and the salt becomes imbedded regardless of flushing. In freshwater after 250 hours, the rust and sediment builds up as suggested above. At some point, it's not worth it and won't work very well and the money might as well be spent on the next motor and additional FWC at that point.

 

[Morpheus]

But on a BIII even with FWC you would still need to flush the outdrive when used in salt water, correct???

 

[Dave M.]

How costly of a job is this?

I think I paid about $650.

Is it even possible?

Yes, if it is anything like my 1996 270 DA with a 7.4L carb engine.

Would you do it?

Yes

Has anyone done it?

Yes, I did it. I did mine in the first week of June in 2005. At that time the engine had 686 hours on the clock. If it had ever been in salt water, I don't know about it. The boat came out of Portland OR, where it was probably used on the Columbia in reasonably deep water; but it did have outdrive damage at one time. But maybe not too much sand ingestion.

Since I did the mod, it has been over two years, and I have put 175 hours on the engine. I have had the engine overtemp alarm come on once or twice after running on plane, then stopping and shutting the engine down without a couple minutes of cooling off idle time. Now I try and let it cool down a couple of minutes. I think my overtemp alarm is quite close to my normal operating temperature, probably within 10 degrees.

I used the San Juan cooling kit. If I were going to do it again, I would seriously looking at getting original Merc parts and use those. I don't know if that is practical or not. The kit contains a lot of hoses and parts, but not the best fit. I bought two or three hoses at the local NAPA store because of fit; the equivalent ones in the kit were a poor fit, and one did not fit at all.

Now I can think of a problem using original Merc parts. On my RWC boat, the engine oil cooler is mounted vertically on the front of the block, as shown in the Clymer manual. On a FWC boat, it is mounted below the port manifold, horizontally. This was the cause of the hose that did not fit at all from the San Juan kit. They insisted that even a RWC boat had the engine oil cooler below the manifold, and that I should make mine like that to be 'normal', and they had never seen one like mine. That would mean moving the engine oil cooler, maybe new oil lines, maybe new mounting bracket. I did not go there, my layout is like in the manual, and I left it that way. But I guess it would be different to make the Merc heat exchanger connection that it was the San Juan exchanger connection.

My engine now warms up much quicker. I don't like running an engine cold, and my cockpit heater also works much better. Also, I am now not dumping sand into the engine block. I am guilty of being in sandy water quite a bit. The antifreeze mixture may also reduce the internal corrosion rate.

If I were doing it again, I would also think seriously about a 'half system'. The difference is that a half system does not run fresh water through the manifold and riser, it runs raw water. With closed coolant in the manifold and riser, they get hot to the touch, and it makes it uncomfortable to work alongside the engine after it has been run. You have to not touch the manifold or cover it with something till it cools down. But if my primary use were salt water, I would stick with the full system.

I replaced the coolant in May of this year, after two years of service. I drained the block using the 1/4" NPT plugs at the bottom of the block. It did not drain well at first, there was still crud moving around in the bottom of the water passage that partially obstructed the draining. I used a dental pick and cleaned out as much as I could, and flushed more fresh water through it before refilling with coolant. When I originally installed the FWC, I used a 1/4" nipple threaded in these holes, with adapters to connect to a water hose. I forced water in those drain holes to try and break loose and wash out all the crud that I could. Obviously there was more left, and now I have more of it out.

After the number of hours that my engine had when I did it, the 3/4" plugs in the manifold and riser that have to be removed don't come out voluntarily. I removed mine like this --> :smt021

 

[Nehalennia]

there are several different layouts that I aware of, maybe the reason for the fit issues. One thing I have heard is that the SanJuan engineering co makes the heat exchangers for Merc. I was advised to go with that the local SeaRay dealer (cost is less) and they showed me 2 installed with no fit issues and they looked really good to me. We'll see

 

[Dave M.]

Todd, you are right that there are a lot of configurations. The remote oil filter mount at the top of the manifold may have been an option, and that is certainly in the same area as the cooling hoses competing for space. I am not trying to knock the San Juan kit, just giving my experience and opinion straight up. I don't know if San Juan makes the heat exchangers for Merc or not, they might. I think the quality of the exchanger I got is just fine. One difference in the model I have is that the Merc unit has the overflow reservoir on top of the heat exchanger as an integral part. The San Juan unit has a separate reservoir that you mount on a bulkhead somewhere. It may boil down (no pun intended) to a patent issue. Or, if I had the Merc unit, I might discover why a remote reservoir is better!

To me, asking when is it too late to quit running your engine too cold and ingesting sand and crud is sort of like asking when is it too late to quit smoking. (talking non-salt water engine) If you don't know you are going to die right away, the answer is never. Granted quitting smoking is cheaper that adding FWC to your boat.

Dave (wandering aimlessly in the world of bad analogies)

"If I'd have known I was going to live this long, I would have taken better care of myself!"

 

[stubing]

I recently bought a 2005 185 Sport 4.3L, 44 hours in only fresh water, and I want to take it into the ocean. Most wisdom says to install FWC, but it is around 3K for the Merc system. The local Searay dealer says they use Orca (vs San Juan) and that Merc will honour the extended warranty with that system. Do I really need FWC and has anyone got an opinion on these systems?

 

[Alex F]

I recently bought a 2005 185 Sport 4.3L, 44 hours in only fresh water, and I want to take it into the ocean. Most wisdom says to install FWC, but it is around 3K for the Merc system. The local Searay dealer says they use Orca (vs San Juan) and that Merc will honour the extended warranty with that system. Do I really need FWC and has anyone got an opinion on these systems?

stubing,
I've used two boats that was towing, both row water cooled. I've used them in different waters. If you take the boat out of the water (ocean) you need to flush your system with fresh water and you'll be fine. Don't forget to flush the trailer as well. If you plan to stay somewhere (lets say you rent a slip for a weekend) in solt water, don't worry about and just enjoy your time while having the boat in the water. But, when it's time to go home you flash it then.

My 2c.
Alex.

 

[jhild]

I'll second Alex's comments. Make sure you flush out the cooling system and wash down the trailer and you'll be fine. I'm always in saltwater, but I clean her up after each use. No worries - You own a Sea Ray, not a Freshwater Sea Ray. If you're still concerned, you can pick up some Salt Away, Salt-X, or something similar to use when you flush.

If you're planning to leave your boat saltwater for an extended period of time, you should probably address things like bottom paint and preventative outdrive maintenance before worrying about a closed cooing system.

 

[stubing]

Thanks for your input gentlemen. I've heard Salt Away is a good product.