Need to Flush in low salt 2 ppt brackish water?

[Godot]

I have a glass boat with a 200 hp 2001 saltwater mercury carbed outboard (SS prop) which I am moving to a boat slip with no flushing water supply available on Clear Creek Texas with an average of 2ppt salinity. I always flushed it before after using it in the bays and the gulf, but do you think I could get by without flushing it under this low salinity which is about 15-20 times less saline than seawater (which is 35 ppt)? I would otherwise have to pull it out and drive somewhere to flush it and I would rather just keep it docked in the water and maybe flush it every month or so. Any thoughts on whether this would be really bad for motor longevity?

 

[arks]

Re: Need to Flush in low salt 2 ppt brackish water?

This is only my humble opinion, but if it's a SALTWATER series then it's designed to be used in that environment. It'll be fine in brackish water with normal maintenance and an occasional freshwater cleaning.

 

[F_R]

Re: Need to Flush in low salt 2 ppt brackish water?

Nah, it isn't going to make much difference whether you flush it or not. Shoot, look at all of the motors that never get flushed after sea water use. Even if you do, it is impossible to get ALL of the salt out.

 

[Home Cookin']

Re: Need to Flush in low salt 2 ppt brackish water?

no problem. flushing is a relatively new protocol and many many motors around here run for decades without ever seeing fresh water.

I wonder if occasional flushing (after 3 months for example) can do any good at all?

 

[dingbat]

Re: Need to Flush in low salt 2 ppt brackish water?

I wonder if occasional flushing (after 3 months for example) can do any good at all?

The motor is hot when you get back to the dock. By the time you get the boat out of the water the block would have drained and the remaining moisture would have evaporated leaving the solids ?baked? to the block. Flushing would remove the loose stuff but not the ?baked on? stuff. You could use one of the salt removal products to but why bother? Most modern outboards are made from fairly corrosion resistant materials anyway.

The bigger issue would be the errosion of the passage ways by the solids found in Saltwater. A nice clean salt free motor interior isn't going to a darn bit of good when your water passages are so erroded away that you end up with water ingestion related failures.

 

[Home Cookin']

Re: Need to Flush in low salt 2 ppt brackish water?

"errosion of the passage ways by the solids found in Saltwater"

Interesting. Do you mean, for example, sand in the water would scour the inside passages? I suppose, as well, that any "baked on stuff' that was knocked loose later would do the same. what other solids might be in salt water and not in a fresh river?

I doubt the water pump creates enough pressure to break anything loose, but the fresh water would dillute the salt and wash away whatever was on the surface. More of a bath than a wash. I've seen the insides of salt motors, scaley and pitted, adn it seems an immediate flush might reduce some build-up, but you can't prevent the effect when the boat is moored overnight, or stopped for a few hours at the sand bar or fishing spot.

 

[dingbat]

Re: Need to Flush in low salt 2 ppt brackish water?

Sand would have an effect as well but, SW in general is very high in solids.

The average salinity of the Atlantic is #35 of solid per #1000 lbs of water. At 8 pounds per gallon, you?re pushing #0.25 of solids per gallon of SW through the motor effectively slurry blasting the inside.

My current motor has well over 2,000 hours on it. Lucky to have been flushed once every 100 hours. Signs of corrosion are minimal. Signs of erosion are everywhere. I have already had the heads planed in an attempt to get a good sealing surface around the water passages. The repair lasted a little over a year before the block itself became pitied allowing water to seep into the cylinders. Used JB to fill in the pitted areas in an attempt to get another couple months out of her.

 

[Home Cookin']

Re: Need to Flush in low salt 2 ppt brackish water?

and you're on the bay side, right? The seaside motors really get the salt.

 

[dingbat]

Re: Need to Flush in low salt 2 ppt brackish water?

and you're on the bay side, right? The seaside motors really get the salt.

Striper guy. Bay in the Spring and Winter. Offshore during the summer.

 

[capt sam]

Re: Need to Flush in low salt 2 ppt brackish water?

I was told years ago that if you didn't flush within 20 minutes or so it didn't really matter, I guess the theory is/was that the salt/minerals have already embedded in by then, I really don't have a clue though. I do flush whenever my boat isn't at a dock and just had the heads off, I had pretty much zero salt build up in the water jackets, I was actually surprised since there 700 hours on the motor.