Replacing Anodes (Zincs) on Honda Outboard

C

CAVU

New member
I have twin 40HP Hondas, 2002, with 460hours. Most of their use has been in saltwater. The zincs are looking pretty pitted. For both engines the parts will be well over $100. Before I order the parts I wondered if the pitting and partial consumption really effects how well they would continue to do the job. After all the anode is supposed to get used up and if any of it remains it would seem logical that it would still be working? Any one have any thoughts or advice on the subject? The shop manual also shows an anode in the cooling system under the water jacket cover. I haven't looked at it yet.
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Ken,

I bought 6 new zincs for the 2 150s (Ouch!). I replaced the large ones under the mount. The 2 smaller ones wern't too bad so I buffed them with a wire wheel and reinstalled them. They should be good until winter at least. With a little help from Google, you can find them online for half price!
 
clean them with a wire brush
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Roger and Steve
....and replace when 2/3 is gone. Suggested to weigh them if questioning. That's what my mechanic said. Also, if you go into freshwater, they should be wire brushed after that, otherwise they get a coating on them that decreases the usefulness when you go back into the salt chuck. HTH
Harvey
SleepyC :moon
 
Interesting that this topic came up today. I have Miss Pam on the hard doing maintenance. Changing zincs was a first order of business. They were changed last 2 years ago. I have had the boat in the water for 3-1/2 years now, only out for 2 weeks for bottom painting. The zincs on my BF 135 were totally consumed in 2 years. They became this crumbly easily broke stuff kinda like dried mud. I also suffered some minor electrolysis on the very tip of the skeg of the outboard. My permatrim, had the most corrosion on the edges as well as some pitting on its upper surface. The engine is kept in the down position in brackish water on a dock with deicing equipment running in the water in freeze conditions. This is more immersion than most may experience. Sorry, I did not take pics. I am repairing the minor pitting with Marinetex per Honda dealer's instructions and will repaint the lower part of the unit with the 2 part spray paint kit from Honda. (factory color and clearcoat catalyst in spray cans) I don't anticipate any long term problem from the minor corrosion which was mostly cosmetic, but I learned my lesson. Moral of the story is: Change your zincs as soon as you see any degradation. This site has Mil spec at a great price and much less compared to Honda so cost of this important maintenance is negligible: http://www.boatzincs.com/honda.htmlzincs
Since I did have some corrosion, I feel I may be under zinced and will add small 1-7/8 inch diameter rudder/trim tab zincs to both the Permatrim and the trim tabs.
 
Pete,
Thanks for that link. The Honda dealer prices are at least three times that! You didn't mention it but did you check the internal zinc? My shop manual shows a round collar type zinc in the cooling water system under the water jacket (40HP). Any way mine are not very deteriorated but I will change them out this fall. At the low prices on your link it won't be too bad.
 
My engine is going in for service in about 2 weeks, new impeller, thermostat,(preventive maintenance, pisser pumps fine and no overheat ever but 3 yrs old) fluid changes. I don't have my manual out, but I'll ask the honda service if there is an internal zinc and change it out also. Ounce of prevention is worth a pound of cure.
 
Based on some of the information above, I ordered new zincs for my Honda 40's. When I actually took the old ones off, I was amazed at the difference in weight. They didn't look much different in size except for the pitting, but when I weighed them on my kitchen scale, the old one weighed 110 grams and the new one weighs 365 grams. It was definitely time to change them. I am getting ready for a trip to Lake Powell and will tackle changing the thermastat and internal zinc after this trip.

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Don't know if the 40 differs from the 90 on zinc placement, but on the 90 the two zincs in the cooling system are accessed by pulling the intake manifold. You'll need a new intake manifold gasket, and possibly an impact driver to unscrew the zinks. You can do it yourself, but will have to be very careful, and might need to do some filling of pits on the mating surfaces.

Let us know how it goes on the 40.
 
Almas Only":3696roy9 said:
Don't know if the 40 differs from the 90 on zinc placement, but on the 90 the two zincs in the cooling system are accessed by pulling the intake manifold. You'll need a new intake manifold gasket, and possibly an impact driver to unscrew the zinks. You can do it yourself, but will have to be very careful, and might need to do some filling of pits on the mating surfaces.

Let us know how it goes on the 40.
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Hello All,
I wanted to bring this thread forward again, to ask some questions to those who have done the replacement of the two internal anodes in the cooling system of their Honda 90's as I am preparing to do so. How often should this be done? How difficult is this procedure? Any photos to share of the procedure?

Thanks,
Grazer
 
Anodes aren't necessarily zinc. They may be magnesium or aluminum. A boat in salt water shouldn't have zinc anodes.

I bought some from a source in Boston and the guy guaranteed they would be MIL-spec zinc. That's not what a motor in salt water needs. I then bought Honda anodes and they were lighter then the zinc ones so I suspect they're not zinc.

Since the 150 engine cost over $10K, I stick with the Honda parts. I get some discount by buying them from boatnet.com.

Also check if your Honda 40's have anodes in the exhaust manifold. I finally checked my 150 and there's 2 there I didn't know about. They're now replaced.

Boris
 
I agree with you Boris, I'll stick with Honda parts for my Honda engine. You may pay a premium but at least you would expect the correct parts in both fit and function. Plus it's pretty easy to look up your part number for your specific engine.
Boris, did you change out the internal anodes in your 150? If so, was it a difficult procedure? Could a guy like me with some handy hand preform the replacement? I understand you need to remove the water manifold cover and therefore require a new gasket? Is there anything else? Would a guy replace the thermostat while he is taking the manifold apart? Sort of preventative maintenance if the thermostat has never been replaced since new.

Grazer
 
When I replaced my internal anodes on the 150, all I had to do was remove the cover plates on the exhaust manifold. I ordered 2 ea new rubber gaskets from boatnet but they were the wrong ones. The original gaskets had a square cross section, they sent me o-rings. Cleaned and reused the original gaskets.

The anodes hadn't been checked/changed in 10 years. Cleaned up the old ones and they looked like new. I'll put them back in in another 10 years.

The 2 lower anodes were $12 each, the upper one $30 and the internal was $7 for a total of $68 per 150 engine.

I could only find a single anode for the 40 and it was $22. Best to check.

Boris
 
The 2003 BF90 is different than your 150 as it seems the intake manifold requires removal to access the two anodes in the water passage.
 
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