Hello guys

I'm working on bringing a I/O boat to fort myers florida. Its been a fresh water boat all its life. I have only had to deal with outboards here so far. I am unsure if i should spend the money on closed cooling "even if it will fit?" on a single 502 HP500 "blue motor" carbed with a B&M blower. Are there kits that will work with this config? Are most of you just flushing when you return to the dock of traileror or using closed cooling. Thanks....

I am guessing that he HP500 has steel heads. Probably just wide port versos the conventional 502. So if they are steel, I don’t know that I would go through the expense and aggravation of converting to closed cooling. Most anything beyond the HP500, Mercury Racing switched to aluminum heads and with that included closed cooling as a standard. Now if for some reason you have aluminum heads, definitely want to go with the closed cooling. So I am annual about most everything that I overthink, and my second impression would be to tell you to go with the closed cooling and give your engine every added bit of a chance to survive the harsh salt water environment. By the way, most everyone still flushes closed cooled engines. You want to take very good care of your power steering cooler, heat exchanger, (intercoolers if supercharged), and exhaust system. OK so here is the aggravation of converting to closed cooling … depending on the age of the engine, you will have a long battle of fighting the scaling that has already occurred in the engine casting. This flacking rust will continue to flake and stop up your heat exchanger. Unless there is a way to acid pickle the block and remove the scale build up. Years ago, I looked into converting my Donzi 22C to closed cooling so that I could enjoy it in salt water. What I found at the time was that the scaling was a big concern. I also found that a lot of “trailered” boats of this vintage were not set up with closed cooling for salt water use, probably due to the ease of flushing. Maybe more in the cruiser class were the boat stays in the water and would be difficult to flush. I am guessing that closed cooling really become more popular just because the racing engines standardized on the setup. I am also told that there is plenty of meat in the engine castings and it will last a very long time as long as you properly flush.

Maybe some folks running non-closed cooling will “chime in” a give you some more direct information. I periodically run the 22 in salt water and just flush it.

Hope this helps, even if just a little bit.

Andy

I ran a 454 magnum in salt water for 10 years with no problems. just make sure you flush it for 10 minutes after every use with out fail.

you still have to flush a closed system or the salt will tear apart the raw water side. the up side benefits are that the motor will never see salt water. salt water, especially down in florida is bad. and no amount of flushing ever gets the all the salt out.

Same here. You'll usually wear out a motor before it succumbs to SW corrosion, provided that you flush after each and every use.

Correct. There's still the whole heat exchanger circuit and the exhaust that sees saltwater, so you have to flush no matter what.

Thanks guys I plan on making the trip....flush kits it is....

I run 2 496's w/ closed cooling and flush after use. Doing 200+ running hours a year, I wouldn't have it any other way.

I'm sure this has been beaten to death, closed system v flush but I'm having the top ends done on my 353 fastech 502s that I'm bringing down to Cape Coral in a few months and I'm having them put a closed system on them while they have them apart.

It's saving me a few bucks to have it done when the engines are apart, it's costing close to 4K for the just the merc closed system (quicksilver) parts to close them up, good idea or am I wasting my money.

I know I'm still going to still have to flush the rest of the engines, I just hate having the salt water in the whole darn thing.

ttt