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aluminum head corrosion coatings

8K views 28 replies 16 participants last post by  River Rat 005 
#1 ·
I bought some brand new heads that where not hard anodised for marine use.The heads are fully assembled can i just take the valve out and have them hard anodized without effecting the guides and seats? or is there some kind of paint or coating can be poured just in the water jackets?This engine will never see salt water.I also drain all the water out of the engine after each weekend.
 
#2 · (Edited)
I had the heads off one of my engines the other day and was surprised at the deterioration of my alum. heads as a result of the water here in Havasu. Made me want to put cast iron heads on it and not waste nice alum. heads. It would be nice to find some way to protect alum. heads from this type of damage.

I have often thought it would be beneficial to plumb fixed block drain lines to the outside of the transom with a open/closed valve to make draining the blocks easy every time I pull the boat out of the water but with the size of the block drain holes I assume they would plug up quickly defeating the purpose.
 
#5 ·
There is a block off that can be applied to keep the hard coat masked. ALOT of areas will need that. It is like a paste and takes a while to get back off/out. All tapped/reamed holes need to be blocked. The additional material that the coating applies will keep the bolts from fitting. It could be done, but I think it would take ALOT of effort to do this after wards. Guides, seats, etc...Maybe if the coater was experienced they might have a more sophisticated method than I have seen. I am basing what I am telling you on what I did when building gages and fixtures that needed the hard coat applied. Our local heat treat company did the anodizing for us too. GOOD LUCK if you do it. I will be interested to see if anyone does have a better way.
 
#12 ·
Thanks for all the ideas guys .I was wonder if i filled the all the water jacket holes up except for one and fill with glyptal paint(the paint they use in lifter valleys)and then drain the head .what do you guys think a recipe for disaster.I know the glyptal is water proof.
 
#18 · (Edited)
I bought some brand new heads that where not hard anodised for marine use.The heads are fully assembled can i just take the valve out and have them hard anodized without effecting the guides and seats? or is there some kind of paint or coating can be poured just in the water jackets?This engine will never see salt water.I also drain all the water out of the engine after each weekend.



I would try and fix a water system I could use that I could circulate liquid glass thru the engine as per the procedure and then drain and let dry, K&W makes some and there are a few other block sealers that use a liquid glass, K&W's has copper in it, wont hurt anything, and adding some zinc sacrificial anodes would help

prolly can set the deal up to treat the engine once a year, and that should be enough

if worse came to worse, put a closed system with a couple of small shell and tube heat exchangers on it and run antifreeze
 
#23 · (Edited)
Check out West Marine, they sell small threaded anodes like the ones found in a good oil cooler. The anodes in my oil cooler have the anode threaded into a brass plug and I think this set up would be perfect for this application.

Although when I took my oil cooler apart the anode had about 3/4" to 1" ball of crud sticking to it, could impede flow under certain circumstances.
 
#25 ·
When you mix metals and add an electrolyte you get a battery.

I'd think iron and aluminum would be bad enough, but brass zinc (on aluminum) would be worse. I'd look for a aluminum holder for the anode.

Hard anodizing only changes things 1/1000". I'd think you'd want the water passages and mating surfaces done but not the chamber...even the exterior (a nice graphite color).

If you didn't block off bolt holes the fit had better be good first. Maybe chase the holes and the bolt threads and dry fit a few times.
 
#26 ·
I cant believe nobody has brought up electrolysis as the culprit. Dissimular metals and poor grounding due to water eats aluminum in a heart-beat. A forgiving metal as in zinc will take the corrosion and save all the coatings. Ocean boats require this or you can eat an out-drive fast. Bolt a zinc plate to the block as the food for electricity to eat and install a battery switch to cut power.
 
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