Anodes in oil coolers

[Andre Huizing]

Goodmorning,
On the back of our QSC8.3 are 2 oilcoolers (see aolso attached pictures)
– Mota transmission oil cooler for the Twindisc
– Mota hydraulic oil cooler of which Wesmar stabilizers, bow and stern thruster run.

The transmission cooler does not have any anode in it which has always surprised me. It is also a more complex devices of which I guess it has some thermostatic function? The (upper) hydraulic oil cooler is a very simple straight through cooler. This one has an anode in it.

As I have heard of quite a few major failures of the transmission oil cooler (corrosion) and I’m very anal on all anodes after an experience years ago when a very big sturdy looking through hull disintegrated on me because of no connection to any anode, I thought let’s electrically connect the non-anode cooler with the hydraulic oil cooler. In the second picture you can see the wire.
However the anode in this cooler now vanishes so quickly (1.5 months) it’s nearly gone when you’ve left the engine room after mounting it. After a more thorough study I see that the hydraulic oil cooler is totally isolated from any connection. E.g. rubber connecting hoses and rubber strips between the mounting brackets and the housing…I guess this was intended…and I guess that in my infinite wisdom I did something very stupid again by making this connection. Hence I disconnected it again today.

Now I still have the “problem” of a non-anodized tranny cooler which is just bugging me, especially while the consequences of a major failure are big. This cooler IS not isolated and just mounted on the motor, so eventually also electrically connected with several other anodes…but they are some distance off.

I hope someone with more expertise than this amateur can shed some light on this matter and can explain why a critical tranny cooler with obviously different metals and salt water in it has no anode and a very simple cooler is isolated and HAS an anode in it?

Many thanks! André Huizing

Topic

[Andre Huizing]

Thanks for all the advice. If anything I found a topic that even Tony is unsure about 🙂 To ponder a little more. We have a Northern Lights genny with a Lugger diesel. In this Lugger there ZERO anodes which always baffled me. However one of the things they did that might explain this, is isolate the core in the HX. This is only clamped in rubber no contact with any other metal. That’s what started me thinking on the isolation of the hydraulic cooler and might explain why, after connecting this cooler to the common ground the zinc disappears at extreme speed. As it is a Zinc zinc it would not even be very useful if there was aluminium present in the cooler…
But I’m afraid we are still in a guessing game here…
Cheers, André

[Tony Athens]

My take — I always thought that all should so be at ZERO potential potential difference, meaning all should have a common ground.. .. I also seem to think that all should have zincs…………Notice the word “thought”.. ..

MOTA , I think, uses aluminum housings on their coolers that have seawater on one side and oil or coolant on the other ????? If so, this adds more to the equation to ponder..

Is my thinking right? No more than the guy on the other side that says “says isolate all” and use anodes as needed……………..

Tony

[dave carey]

Option

Andre,

Does the oil cooler have small plugs (~7/16)on either end? My engine does and I was able to get small pencil zincs into the cooler by cutting them down to 3/4″ length not much but maybe better than nothing.

Dave

[Rob Schepis]

Andre,
I cannot tell you what the couch engineers were thinking when they designed/built different coolers. It does sound like you have some things going on there that should be investigated as to corrosion potential. I’ve found/corrected some issues using this setup: https://www.boatzincs.com/corrosion-reference-electrode-specs.html

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Andre Huizing

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