Salt-Neutralizing for Marine Engines: Royal Flush

Even before you buy your first boat, you know it’s essential to flush your engines after running in salt water. But even if you flush your engines religiously, you can still end up with corrosive saltwater languishing in your engine. How? We asked Alan Landry, owner of Pacific Marine Repair in Ventura, Calif.

“If we ran around in salt water, and then flushed it, then the following day took some of the water out of the manifold, it’s going to be salty because the metals are so porous that the salt gets in there,” he said. “In flushing, you’re not going to get the same expansion you get at 3,500 rpm under load out on the ocean. The block is going to be much warmer. The expansion rate is going to be much greater.”

Volvo Penta's QL Neutra-Salt Engine Flushing System

So it’s a good idea to install a salt-neutralizing, engine-flushing system on your boat. It’s not cheap, and it takes a bit of work to install one, but if you boat a lot in salt water, it can save you the greater expense of corrosion-related repairs.

MerCruiser doesn’t offer such a system in kit form, but you can get a kit from Volvo Penta  for about $280.  It can be installed on virtually any inboard and stern-drive engine that has a suction-type sea pump, usually driven by a belt on the engine. Unfortunately, the system won’t work on boats with Alpha drives, because they have push-style impellers located in the stern drive’s lower gear-case housing.

To install the system, mount the reservoir high on a bulkhead, where gravity will help deliver the solution into the raw-water feed hose before the sea pump. Cut the raw-water feed hose and install the kit’s connector, which features a T port through which the neutralizing solution will flow. Then wire the valve beneath the reservoir to a power source and a dash-mounted switch, and it should work. Or if electricity baffles you as it does me, just have a shop install the kit.

Landry recommends flushing the engine first, getting most of the salt water out, then during the last 60 seconds of your flush, hold the switch down and allow the solution to circulate, then shut it off. That allows the solution to sit in the block and manifolds and risers and neutralize the effects of the existing water in the system.

As your engine cools, saltwater that leached into the porous cast iron surfaces within your engine will begin to weep back out as it contracts. When that happens, the solution is present in the system to neutralize the salt. However, because the solution is introduced in the raw-water line, the Neutra-Salt system will not protect drive water passages.

Over time, a salt-neutralizing engine-flushing system will make a huge difference in the condition of water passages and junctions inside your boat’s engine. Because the water that remains in the system when the boat is not in use has been neutralized, corrosion is kept to a minimum. The flaky rust that often collects on manifold risers accumulates much more slowly.

“We can definitely see the differences,” Landry said. “We know for a fact that they work. I try to sell them all the time. It’s a much more positive way to do it, rather than connecting it to a flush hose at the water pickups.”

Brett Becker


  1. An says:

    I have a 260 Sea Ray Sundancer that I trailer would this kit still be a good value for me. Tha Volvo Penta parts place by me told me just as I pull the boat on the trailer hold the button for 40 seconds and then turn the motor off and it’s done, your way makes more sense. Could I just buy one of those 5gallon Camo winterizing kits and pour the solution in their to add to drive and the engine.

  2. Brett Becker says:

    If you mean Camco winterizing kits, that solution is not a salt neutralizer, but an antifreeze used for filling the engine block during winter storage. I also don’t think it’s environmentally friendly to discharge propylene glycol into waterways.

    The way the Volvo Penta parts place told you to do it is probably fine according to their instructions, but the way the source for this story recommended flushing the engine is a more complete way to perform the procedure.