Salt Water Engine Ssystem Descaling

[GERRYS6434]

Thanks to all for info on where to buy cleaners.

[SKYCHENEY]

I was just in HD tonight. FYI, I saw the cleaner on the shelf in the paint section, right next to the strippers and next to TSP. I think the bottle was green and said Phosphoric Rust Converter on it.

[Genesis]

Yep - that's the stuff.

Works great for this purpose. Don't tell the guys who sell the "marine" stuff at 5x the price...

[REBrueckner]

When using phosphoric rust converter for descaling raw water cooling,

What mix is used? (How much dilution?)
Are zincs removed prior to its use?
How much is required?
Is it necessary to have it in the cooling system for, say, four hours like Rydlyme??
And if it's flushed through an engine briefly, say for just a few minutes, it is again used for a second engine or is a fresh batch required?

I'm a little leery of putting acid in my engine without some further advice. The Rydlyme is likely a lot more expensive, but not if it avoids some potential cooling system damage I might unwittingly inflict!!! Thanks.

[Genesis]

Dilute 1:1 with water.

Remove the zinc pencils first. It won't eat 'em fast, but it will eat 'em.

I mix it up in a 5 gallon bucket and put a "disposable" bilge pump in there as a circulation pump.

Circulate for about a half-hour. No need to let it sit for hours. 30 minutes to an hour will do the job just fine. Keep the circulation going the entire time as it DOES bubble and of course airlocks will stop the process since the surface won't have any liquid in contact with it.

Resuable for second engine, etc if you wish - no problem there.

Note that this stuff is a rust-converting primer used for prep before galvanizing and such on ferrous metals, and is typically NOT neutralized before overcoating when used for that purpose. I would not use it on a cooling system that had aluminum in it, but then again I wouldn't own a boat that had aluminum in the raw water circuit in the first place - IMHO that metal has no place in the raw water side of a cooling system anyway.

IMHO its MUCH safer to use than the Oxalic/Hydrochloric mix that DD recommends. The latter is extremely aggressive - both to metals and to you, if you manage to get some of it on you.

Oh, and Rydlyme IS an acid......

[REBrueckner]

Gensis..thanks for the feedback....

I checked in my local Home depot paint department (in NJ) for "Phosphoric Acid metal cleaner.."
"We don't have that" all three guys in the paint department said, so I said
"Sure you do, it's in with the paint preparation chemicals, strippers"....

So one took me along to strippers and sure enough it was alongside the TSP...called Phosphoric Paint Preparation of something similar, large containers (about a gallon) were just under $7...The can says to dilute 3 to 1 for cleaning metal in preparation for painting....It's on my list for the next impeller change....


Any suggestions on how to make a convenient fitting to feed the chemical mix in the cooling system?
I guess a flat plate, center hole drilled to permit mounting to the raw water strainer assembly, maybe an old raw water pump cover, with a hose connection fitting soldered over a drilled (off center) hole would enable me to fasten it on my intake strainer ....any simplier solutions??? (I knew I should have saved that last raw water pump cover I discarded!!!)

[Maynard Rupp]

I would drill and tap the old plate for 1/4" pipe. Buy a brass 1/4" npt. to hose for whatever size hose you want. Put some teflon tape on the fitting and screw it into the old plate. Apiece of hose and a clamp are the only other needs.

[Genesis]

Remove the impeller and run a hose off the tap on the gear cooler for one of its zincs. Close the seacock so you don't lose solution down that direction.

Remove the outlet hose from the H/E and make up an adapter for that end too.

There 'ya have it.....

[REBrueckner]

Genesis..that's a clever idea to circulate the cleaner via a gear cooler connection...
That way it seems like it would not even be necessary to remove the raw water impeller since there is nothing on the inlet side except the strainer and pick up pipe...no heat transfer elements there...hence a simpler approach overall..or am I missing something??

[Genesis]

My gear coolers are on the suction side, so I have to remove the impeller