Closed Cooling System Anode

[mole2]

I have a 2005 Trophy with a 4.3L 190hp FWC engine and Alpha 1 Gen II drive and I'm told it should have an anode in the heat exchanger. Other than the pressure cap, the only plug I see on the exchanger is a brass plug located on the starboard side. You can see it in the picture below. I removed that plug but there is no anode under it nor anywhere to install one. This is a stock Mercruiser FWC full system with a belt driven raw water pump that was ordered by me as an option from Trophy when the boat was new. Can anyone point me to where the anode is installed or, if it's supposed to be where that bronze plug is, what i need to purchase in order to install one. Thanks.

 

[Don S]

Re: Closed Cooling System Anode

Merc is getting away from using any anodes at all in the heat exchangers, but if you want to install one, where that brass plug is, is the place for it.
You need one like This
You will need to remove the end cap off the heat exchanger and clean out the remains of the old one at least yearly, or it will plug up the HE.

 

[mole2]

Re: Closed Cooling System Anode

So is this a case of we're darned if we do and darned if we don't Don? Or is it I'm better off leaving it as Mercury left it? If it's not really needed then I'm prone to leaving it as is. And we do miss you on the other board.

 

[Don S]

Re: Closed Cooling System Anode

I've seen heat exchangers with and without anodes. The only ones I have seen that go bad are the ones where the drive and other boat anodes are not replaced when needed.
If you keep up with the other anodes, the heat exchanger should be fine. After all, it should be bonded to the engine thru the mounts or clamps so the drive anodes should protect it.

 

[mole2]

Re: Closed Cooling System Anode

Thanks, Don. Just to ease my mind I want to make sure it's bonded to the engine. If not, it will be. Once again, thanks.

 

[wire2]

Re: Closed Cooling System Anode

I'm afraid cathodic protection doesn't work that way. Anodes are placed in an electrolyte (water) and electrically connected to the metal parts to be protected. It forms a basic battery, current will flow from the anodes to the aluminum outdrive parts, (cathode). Oxygen forms on the anode, combining with the metal, (usually zinc) and slowly consume it, while hydrogen forms on any exposed aluminum outdrive part, protecting it.
Still with me? Ok.
The current from the outdrive anodes can't travel travel along the water passage to the inside of the HE.
*If* it needs cathodic protection, it has to be inside the HE to work.
But what is an HE made from? If stainless, should be no problem. Aluminum? Maybe.

 

[mole2]

Re: Closed Cooling System Anode

... But what is an HE made from? If stainless, should be no problem. Aluminum? Maybe.

Thanks for the info. The HE appears (in color) to be the same as your radiator in your car - a goldish color. So my guess would be bronze (I would hope not brass). As DonS pointed out Mercruiser is not putting the anodes in the exchanger. My guess is they have determined it isn't required. This boat is trailered so it's not imperative that it have it. BUT...as I previously mentioned, I was told by others to check it and I didn't find one to begin with. That was the reason for the question.

 

[wire2]

Re: Closed Cooling System Anode

If it's made from stamped sheet, it's very unlikely that it's bronze. The "gold" color suggests to me that it's cadmium plated steel.
Try a magnet on it to see.

 

[mole2]

Re: Closed Cooling System Anode

If it's made from stamped sheet, it's very unlikely that it's bronze. The "gold" color suggests to me that it's cadmium plated steel.
Try a magnet on it to see.

Look at the picture above. It's not stamped sheet. It fails the magnet test so it's not steel. It sure does look like a bronze (like the plug in it in the picture) and is quite heavily made. It's an OEM Mercruiser full system with belt driven raw water pump.

 

[RCSConstruction]

Re: Closed Cooling System Anode

Mine appears to be copper.