anodes

[bill2452]

This has probably been asked before, but couldn't find the exact answer I'm looking for on the search feature. I have a 2011 DF175 on an aluminum boat, moored year round, used primarily in fresh water. About 3 weeks out of the year I use it in the salt. Are aluminum anodes the way to go? I find contradicting info on my web searches. I can find the round aluminum anodes for the crank case but can't locate the aluminum anodes for the gear case. Does anyone know where to find the aluminum gear case anodes? If so, what is he part number? Thanks for any help.
Bill

[Harper]

The aluminum anodes #55321-87J00 for the internals of the engine (5 of them, if I recall) are the same as the anode on the front bottom end of the swivel bracket for salt water use. But you should use the round magnesium anode part #55321-87J10, in place of the one on the swivel bracket. Keep the same aluminum anodes in the engine block. Your other external anodes, the two rectangular ones on the sides of the lower unit, and the big one at the bottom of the clamp bracket, should be magnesium for fresh water, zinc for salt water. I think you're okay to just keep the magnesium on there if your salt water use is very infrequent. Be sure to clean the deposits off the internal aluminum anodes occasionally.

[bill2452]

Thanks for the response Mike. I have aluminum anodes ordered for the engine block. However, the info I've found (depending on which info I read) states to absolutely not use magnesium in the salt. They even show pictures of short exposure to salt when using magnesium that shows the paint bubbling from using magnesium. I'm not a "the sky is falling guy" but just want honest, educated, been there, done that opinions. Still looking for the part number for the aluminum anode for the gear case. If they sell aluminum anodes for the engine block, I would think they make aluminum anodes for the gear case. Maybe others will jump in here and make this a 4 page thread.
Thanks!
Bill

[Harper]

Okay, if you've seen that evidence of trouble using Mg anodes in salt water, then by all means, heed that. My opinion that they were probably okay for infrequent salt water excusions was only a guess on my part. Are you using an Al anode on the clamp bracket? I didn't know they made any in Al. You might just have to get Zn anodes for the gear case and swap them out when you go out in the salt.

Come to think about it, I don't think they make anything but Zn for the gearcase.

[bill2452]

I haven't personally seen damage caused by using magnesium in salt, just pics on a website of an anode manufacturer. They said even short duration can cause problems so that's what bothered me. Agreed, I can't find anything on the gearcase except zinc so I guess that's what I'll use. Looking at the charts below is what caused my concern. It looks like aluminum is suitable for all water types.

[bill2452]

Anode update

Well, here's some more anode stuff to kick around. I now have all aluminum anodes on my 175. I installed the 5 aluminum water jacket anodes about a year ago but couldn't find anything for the lower unit. After lots of searching I found aluminum anodes for the lower unit. These included the button anode which is the same as the ones in the water jacket, the 2 rectangle anodes on the sides of the gearcase, and the long rectangular one on the clamp bracket. I finally got around to getting the boat on the trailer and into my shop. Here's the part that is puzzling. After removing the 2 rectangular ones on the sides of the gearcase, it was very obvious that they were zinc by comparing the weight with the new aluminum ones. This is what I expected. I removed the long rectangle on the bottom of the clamp bracket and compared it to the new aluminum one. They weighed the same. The stock one was aluminum. I'm certain these were factory installed. Every anode is now aluminum, but why was the original one on the bottom aluminum but the 2 on the sides zinc? Just throwing this out there for discussion and passing along the info I've found.