02-29-2012, 04:37 AM #1
Sacrificial anodes - how well do they work on a polaris?
ive owned many 700cc polaris domestic engine powered jetski's and i find time and time again that the cast aluminium exhausts suffer bady with rot.
(i ride in the salt)!!
ive just had to scrap another exhaust off and the casting on the top four bolt flange Swelled and burst two holes into the main exhaust gas path. not repairable. new OEM exhausts are £700+ GBP! luckily i can get fresh water pipes from USA shipped over to england, but still pricey
i find the red powercoat finish dosent last long, and having stainless bolts into the alloy castinh + salt water doesnt help!
so when refurbishing the exhaust, ive found that epoxy primers, and 2 pack automotive paints work very well. this time im going to look into zinc chromate and different types of etch primer. ive also used sacraficial aluminium jet engine paint from work which does work well. - anybody have any views?
but this has got me thinking. all the ski's ive had have had OEM sacrificial anodes fitted to the jetpump. this is fine, but it dosent provide an acurate path for earthing the anode to the engine. so by default, it may accelerate corrosion between different metals instead.
im by no means an electrolysis expert, but by what i can find on the web, it shows the external anode is typicaly earthed to a main engine block, or stern drive assembly.
so i now plan to run a thick earth cable from one of the four jetpump housing bolts, to the cast exhaust via a threaded bolt hole in exhaust. (flange by the rear port engine mount)
can anybody see any problems with me doing this? it may help.
02-29-2012, 10:05 AM #2
Check out Mercruiser's Mercathode system. some of the web pages i found give a good description of the electrolisis process & may help you better understand what's going on. I was tempted to try to use their system on my saltwater skis.
02-29-2012, 12:28 PM #3
i found this website good http://www.mgduff.co.uk/leisure-craf...ode-selection/ as it cearly shows that the anodes mist be earthed to the engine block, and other seperate metal units.
im def guna run a 8mm copper earth cable from jet pump housing bolt to exhaust
hopefully my anode wont last long, then i know its working
02-29-2012, 01:16 PM #4
You Are going to need a good solid link between all componants to be protected.
03-01-2012, 03:53 AM #5
yep, i agree. the next question, is where can i mount a better anode, so its constantly, or more often in the water? the OEM anode wont get wet when the ski is on plane.
03-01-2012, 08:29 AM #6
03-01-2012, 11:37 AM #7
The reason I say this is because that wire in the pump area is going to corrode. It wouldn't take much effort to replace that short piece when it's done. You could routinely check resistance between the anode and the engine exhaust connection. When you start seeing resistance just replace the short wire.
03-01-2012, 03:11 PM #8
03-01-2012, 08:06 PM #9
- Join Date
- Sep 2009
I was under the impression that electrolysis is only a problem if you leave your boat in the water all the time?
03-01-2012, 10:32 PM #10
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