Rusty Section of Heat Exchanger

[rick3452]

Hi guys.... Just pulled the covers off the Heat Exchanger to take a closer look.... What I noticed is the " section " of the HE that has the Pencil Zinc is really rust colored. The Pencil itself is rust colored and the opposite side of the HE is completely also rust colored and I noticed a few clogged.tubes. Im going to "rod-out" the tubes with a 1/8 welding rod, but is there any reason that this is happening.?? Lots of "greenish" on the larger section.
Thanks as always... I truly appreciate you guys.
Rick

 

[alldodge]

Are you in salt or fresh water?
Also the rust your finding is on the raw water side and not the engine coolant side?

Also got any pics?

 

[Scott Danforth]

on a mercruiser, you can only get to the raw water side by pulling the caps. fresh water side is brazed into the shell.

Im going to assume that since the zinc is still there, your either a trailer boater, or you do not boat in salt water much (they last a max of 6 months in salt water with any amount of use).

my first assumption is minerals in the water reacting with the zinc. clean the zinc off with a wire brush, re-install, go boating.

my concern is the plugged tubes. if you have plugging going on in the HX from debris, make sure you pull the power steering cooler and clean that out too. normally the crud plugs the PS cooler way before you get debris in the HX.

 

[rick3452]

Thanks guys, Boat is in Brackish/Salt water and used daily. When not in use its on a lift at the dock. Yes pencil zinc is there and less than half worn I do keep up on the pencil zinc. I did pull the Power steering cooler and was "clear" I'm going to Gently rod out the tubes tomorrow and keep an eye on it. Heat exchanger is about two years old.
Rick