Heat Exchanger Service/cleaning intervals

Hi,

I replace the pencil zinc in the heat exchanger on our 1984 E30+ about every five months--a ten minute job at most. Yesterday the brass nut/piece came out with no zinc attached, and looked as if it had broken off rather than corroded. I fished around in the hole and felt the broken piece inside the heat exchanger. I tried to remove the end cap, but it was very awkward to reach and then wouldn't budge. I briefly debated leaving it, but decided that I would risk it clogging the narrow passages resulting in engine overheating.

So I spent the rest of yesterday draining the coolant and raw water side of the engine, removing the hoses (with some difficulty!) and then the heat exchanger itself. With it now free and clear I was able to remove the end cap easily and immediately saw the broken piece inside. I was able to remove that piece with needle nose pliers. However, I also noticed that the passages were starting to be obstructed by calcium (or whatever) buildup. It was last serviced--cleaned, new rubber end gaskets, etc. a little over three years ago, now 500 engine hours later. My normal interval for this is about 5 years, so I was surprised to see that it seems to need it already.

So my question is how often you have your heat exchanger checked and cleaned in a salt water environment? And for those of you who have no idea what I'm talking about, maybe it's time to do this job! But it's only needed in fresh water cooled engines, I think. I'm also taking the opportunity to replace a couple of the heater hoses--they still look fine, but have been there a long time and it's easy to replace them at this point with everything apart.

Thanks,
Frank

Good job. I think it varies with the environment. The pencil zincs in my current HX last almost a year. However, lat month when I unscrewed the base it left the zinc behind. Huh? It turns out that unscrewing the nut also unscrews the zinc threads. So I learned, when using pencil zinc inserts (changeable using the same base), to screw them into the base hard.

On the 32-3 it was pretty easy to reach and service the heat exchanger, and I could even change the end-cap gaskets and probe for glop with the Hx in place. The E381 engine compartment is much less inviting, and checking the pencil zinc is awkward.

The problem is too much permanent furniture around the engine. Looks nice and that's about all.

Thanks, Christian. I would certainly pay extra for a boat that was user friendly for maintenance. Our E30+ is pretty good for most things, but still.

I'll be glad when I get the heat exchanger cleaned and reinstalled. I hate it when the boat is in pieces for any reason.

Frank

Frank:

I change the zinc in the heat exchanger on my 5432 once a year and there is usually 1/4 left. I do however have a fresh water flush/bypass for the raw water side of the system and give it a flush when I return from any trip - probably extends the life of the zinc and the exchanger. That said, and after 27 years, I replaced the exchanger 2 years ago (having previously had it serviced/boiled out every 4 years or so). Also replaced all the hoses 10 years ago; have recently replaced most of the hot side hoses around the engine again; the cold side hoses are still in pretty good shape.

Good info to have

Good thread link for zinc's and heat exchanger information.
http://www.ericsonyachts.org/infoex...Exchangers-Up-Close-amp-Exposed&referrerid=28

Thanks, Loren. That was very helpful!
Frank

Frank Langer said:

Thanks, Loren. That was very helpful!
Frank

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I don't know if it helps but we show removing, "field" cleaning, and checking the zinc on our E38's engine in our latest Two Afloat Sailing video on YouTube. I don't have the bandwidth here to get the link but it should be easy to find. I think Nicole named it "Boat Love." Good luck! BTW, we check the engine zinc about every 2 months and replace when it's about 1/4 dissolved (still 3/4 intact). They are inexpensive and it is quick/easy to checking/replacing them. Much easier than fishing the broken pieces out and/or damaging the heat exchanger.

Thanks, Ryan! That's very helpful. I think I left my pencil zinc replacement too long--usually about 4- 5 months, at which point it was about half gone or a little more. This last time it looked less worn, but had gotten soft and I think that's why it broke off inside. Although frustrating to have to drain the system and remove the heat exchanger for cleaning, in the end it was good that it happened because the heat exchanger tubes were already a bit crusty inside. I had been cleaning it every five years, but have now shortened the time frame to every three years in my maintenance plan to ensure I don't leave it too long and risk the engine overheating.

Frank

Frank Langer said:

Thanks, Ryan! That's very helpful. I think I left my pencil zinc replacement too long--usually about 4- 5 months, at which point it was about half gone or a little more. This last time it looked less worn, but had gotten soft and I think that's why it broke off inside. Although frustrating to have to drain the system and remove the heat exchanger for cleaning, in the end it was good that it happened because the heat exchanger tubes were already a bit crusty inside. I had been cleaning it every five years, but have now shortened the time frame to every three years in my maintenance plan to ensure I don't leave it too long and risk the engine overheating.

Frank

Click to expand...

Thanks for posting this stuff, I bet it will help people.

Another point that may help is to mention that we've come tried a variety of different diameter and length zincs. In our experience the wider/shorter ones last longer than the narrow/longer ones. It also may be good for people with quickly eroding engine zincs to note if their shaft/strut/prop zincs are also eroding more quickly than expected. Especially if they are often plugged into shore power at a marina...

Glad your heat exchanger is solved!

My pencil zincs always seem to decay most quickly right above where they screw into the brass nut. Makes sense, I guess, that galvanic corrosion would be worst where the two metals are in direct contact. This makes them prone to break off at the base well before all the zinc has been used up.

Borrowing a trick I learned from the Compass Marine (MaineSail) website on preparing shaft zincs, I started painting the base of the zincs with nail polish; the thought being that the nail polish limits contact with the salt water (electrolyte), hopefully causing the corrosion to occur further out along the zinc.

A new trick for me--results unverified....

That's an interesting idea, worth trying!
Frank