Another Zincs type anode question

This is my first time replacing the zincs in our boat. For background, The boat was previously on fresh water on Lake Union. Taking the old zincs outs, a couple of interesting things I noticed.

1. The Seawater that spilled from the transmission Cooler on the SB side has chalky white precipitate. The port side seawater looked clear. One of the zinc pencils that I took out the SB tranny cooler seems to contain white chalky material below the surface.. could that be a Magnesium or Aluminum anode?. Not sure what those would look like. If you have experience with the mag or AL. anodes, I would appreciate your feedback.

2. On the port side of the Heat exchanger there are 2 anodes.. one was completely used up, the other was almost untouched except for slime and minor corrosion on it.

3. The previous owner did not install one of the two anodes in the Port side of the Port engine tranny Cooler. And wrote on that side... No Zinc.. why would anyone not install a zinc in one area. The SB engine tranny cooler has 2 anodes.. not sure of the logic. Maybe they doubled up on the Opposite anode to make installation simpler. Is that something reasonable to do?

I would greatly appreciate any thoughts of opinions..

Thank you

Streff

Interesting question. I'm in FW and use [EDIT Al] all around.
I do frequently find a whitist corrosion product on the pencils when I pull them to check / replace. No real experience so can't compare to zinc.
Heres an interesting note I found with a search

"It's been a few years now, but I recall that if you file the metal and put vinegar on the zinc it'll foam up a bit. On the aluminium the vinegar will stay clear."

Also density of Zn about 2X Al if you can compare with something known.
Also file it Zn surface duller gray Al brighter nearer white?

Ideally, freshwater should have magnesium anodes; brackish should have aluminum; salt should be zinc. In general, aluminum will cover all 3 and zinc is of minimal value in freshwater. Think it's only a matter of time before zinc goes away and aluminum is for brackish and salt. If you look at Side Power thrusters, they now only offer aluminum anodes.

Ted

Absolutely use either aluminum or magnesium in fresh water. If the boat was in fresh water and had zinc anodes they get a coating on them that will make them ineffective. However do not use magnesium in salt water. I would put anodes where ever the manufacturer designed for them.

Thank you all for your input. I did buy Zinc anodes this time around, but possibly look into Aluminum next time. I have attached a photo of the sea water that came out of the tranny cooler. The white material did in fact precipitate at the bottom of the bucket. Since the boat was in FW, maybe the previous owner used magnesium or aluminum anodes and one of them gives off this whitish material. I just don’t know.

On another anode note, looking at the torque values for the zinc plugs in my CAT 3208 manual and the values are insanely high. More than the capability of my torque bar. Something is not right. These plugs were not too difficult to unscrew.

Thanks everyone.

Streff

Streff,
Put a little sealant on the threads (like Rector Seal 5) and tighten enough to not leak. High torque is not needed and could lead to damage to your coolers.
I know some will come on and say "don't use sealant" as it will stop the electrical conductivity. Not so. Urban myth. If doubtful, try it and test it for yourself.

I don’t use any sealant on my anodes and they don’t leak.

Good. I do, and mine don't leak eitherThe main point being, you don't need excessive torque.

I bet the torque values seem high because they are inch pounds, not foot pounds. I doubt they are over 10 foot pounds.

Hoping Streff is around- or anyone with CAT 3208's from 1983 (01Z serial) - I have a question about anodes. We acquired a 1983 Californian 38 with 2 3208's. We are checking all maintenance items and can find 1 anode each engine (Starboard side bonnet, bottom of end- like an oil drain plug). From reading some information I have and online it seems there may more - but I don't see it. Any idea of exact locations of anodes on these engines or maybe a schematic of maintenance areas? Any information or reading material would be fantastic! I see places online to order service manuals (30-75$ digital) but not sure if I trust those. Thanks!!

On my 3208 NA CATs (1981 vintage), there are anodes at each end of the heat exchanger (one in each bonnet). i believe there is one other plug in the bonnet where the raw water initially comes in but any regular zinc hits the divider in the bonnet and won't screw in so I treat that one like a drain plug and leave it without an anode.

If yours are TA versions, it might be different.

This sounds like it may be the case with ours- thanks for your reply and we will check when we visit the boat again! (The Westerbeke site for the generator has lots of old information and schematics showing the zinc in the generator, etc., but seems like the CATS info is not readily available.) Should be easier to find info in this digital age!

CAT 3208 1Z0-up Anodes

Lucky, Lucky, Lucky I found the Parts Catalogue with Diagrams booklet in our boat file box. Our boat is in another city so I couldn't look until this past weekend. Thank you to the previous owners for keeping all boat booklets safe and aboard! No wonder that it is difficult to find part locations and numbers. The catalogue I have sells for $175 online! Nothing digital online unless you pay $$. (If you are looking for a diagram/parts let me know!) I am attaching the pages showing the anode ("Rod" and "Plug") locations for CAT 3208 Marine Engine serial 1Z0-up for our 1983 vintage. Hope it helps someone else as this was exactly what I was looking for on this forum.

3208NA zincs diagram

Hi noticed you mentioned you had a diagram of zinc positions for the 3208 NA/

I have been trying to find one, my engines only seem to have one zinc on the starboard side bonnet (heat exchanger). I would appreciate it if you could P.M.me a copy.

Many thanks