old pencil zinc remains...

[RonE]

Good afternoon(morning),
Getting my boat ready for another season in New York. I replaced my zincs just before I launched last week. Every time I replace the pencil zinc the remains break off in the heat exchanger. I read somewhere that leaving the remains in there could be a problem. I took off the cap ends of the exchanger, but I cant figure how one would be able to remove chunks of zinc. 
Should I just leave the zinc remains in there and hope they desolve or find a way to get out??
Thanks Ron
Stolen Moments 615

[KWKloeber]

Yeah.  Zincs don't dissolve. They galvanically corrode.  Without an electrical connection (to the fragments), nothing much  happens.

Pieces inside can be real trouble and block the. Hx tubes so you may need to remove the Hx and shake pieces out.

If the pencil is that fragile, consider changing more often.  Or find the problem and eliminate  the electrical leakage, or if its from a dock neighbors boat or marina, install a galvanic isolator.  Which is a good idea no matter what.

Also you Hx needs to be well bonded to earth. If its not, the problem may be a lot worse than the corroded zinc indicates. To bond it, run a GREEN 14 ga from the Hx cap bolt (3/8 lug terminal) to a good earth.

[Ron Hill]

RonE : I'm going to guess that your boat is a late 87 or an early 1988.

As Ken said, the old broken pieces of Zn will just rattle around inside and somewhat inhibit the flow of raw water in the HX.  I'd remove the HX -- just disconnect the IN and OUT raw water hoses and remove the 2 clamps.  Take the HX to a radiator shop and have it "boiled out'. 

Contact Glen Mar marine (800-282-0123) and get a new end cap assembly (#5373) with some new gaskets.  With the cleaned out inside and new end caps/gaskets, your HX should last another 20 years.

A thought

[Craig Illman]

I'll need to admit got caught with this about a week ago. I've had my boat about two years and religiously check the HX zinc quarterly and probably replace it semi-annually, but since it hadn't been overheating, I had never removed the end caps. So, all of a sudden it starts running ten degrees higher and I'm getting more steam than usual out the exhaust and we're in pretty remote waters. It would go down to normal when we reduced RPM to around 1800. When we got to our destination that evening, I started looking for restrictions, first the injection elbow, then pulled the end caps and rodded out some of the tubes with a straightened coat hanger, and checked the raw water impellor. The Perko raw water filterwas obviously the first place as well and was being checked daily. While rodding the tubes, a short chuck of historic zinc popped out, something left from a P.O.'s untimely maintenance. So, lesson learned, always check for leftovers.  My G.F. is impressed by my boat systems knowledge and feels very safe travelling with me. I intend to not disillusion her.

Craig

[karista]

RonE : I'm going to guess that your boat is a late 87 or an early 1988.

As Ken said, the old broken pieces of Zn will just rattle around inside and somewhat inhibit the flow of raw water in the HX.  I'd remove the HX -- just disconnect the IN and OUT raw water hoses and remove the 2 clamps.  Take the HX to a radiator shop and have it "boiled out'. 

Contact Glen Mar marine (800-282-0123) and get a new end cap assembly (#5373) with some new gaskets.  With the cleaned out inside and new end caps/gaskets, your HX should last another 20 years.

A thought

Ron, be advised that Glen Mar Marine no longer sells retail for at least the last 3-4 years. They only sell wholesale!