Ask Captain Chris About Changing your Engine Zincs

Engines have anodes in most heat exchangers. Look for the "bolt" that isn't painted.

This is starting to deteriorate. Inspect the zinc for degradation and need for replacement.

I spy an unpainted bolt head in the bottom left corner of this photo.

The wrench is on the bolt head of the anode in the transmission cooler.

I have my finger over the hole where the anode was which will slow down the speed of the water leaking into the boat.

All of these crumbling anodes need replacing as they are no longer effective. These four pencil zincs were removed and replaced. You can see the evidence that the old zincs were exhausted and in need of replacement.

Be sure to remove the sales sticker/label to make the anode more effective.

So you want to learn about changing your engine zincs. This is a simple yet sometimes forgotten preventive maintenance that most owners can DIY.

You know about the zincs on your shaft, rudder and trim tabs?. Uh-oh,…you don’t? The short answer starts with this: There are electrical charges that will flow through the sea water from the harder stainless steel shaft to the softer metals of your boat such as the bronze propeller. These electrical charges can erode the metals on your boat. So how do you keep your metals from being eaten away by this electrical charge?

The job of a zinc

The job of an anode or zinc is to prevent erosion of the important metals aboard your boat. Place a sacrificial softer metal called an anode (in salt water we use zinc) in specific locations like the shaft. Secure the zinc (anode) near the metal you want to protect on the underside of your boat. The anode is used to attract the charge in the water to itself rather than the harder metals of your boat.

Your trim tabs, rudders and tubing inside the heat exchangers of your engines are other essential metals to protect using anodes. Check with your boatyard to determine if you should use zinc, aluminum or magnesium anodes to protect your boat.

What about the pencil zincs in your engine cooling system?

Pencil zincs are sacrificial anodes to help reduce the electrolysis between two different metals in the raw water inside the heat exchanger. Check your engine owner’s manual for pencil zinc inspection frequency. And, be sure to check out these photos of a zinc replacement procedure aboard a boat.

Want to learn more about your heat exchanger and what the anodes are protecting? Of course you do. Read this article for a little more detail about where to find zincs.

And, to become more comfortable in your engine room, come to a two day seminar Introduction To Boat Systems where you can Ask Captain Chris all about boating. Need MORE???? 772-205-1859