Thermostat Bore corrosion revisited

[panasonic]

That two part epoxy primer or just the spray can stuff?

If you can find it, the two part stuff is much better.

[ollie366]

I had corrosion of the block at the tstat caused by dissimilar metal corrosion between the aluminum block and copper "arms" of the tstat. I cleaned the block to clean metal and applied 5200. I inspect it 2x a year and after 3yrs, it's still tightly adhering to the block. Yamaha added an anode to the tstat housing in later motors than mine, which I installed, so that should help. Really bad design/ materials selection.

[pstephens46]

I had corrosion of the block at the tstat caused by dissimilar metal corrosion between the aluminum block and copper "arms" of the tstat. I cleaned the block to clean metal and applied 5200. I inspect it 2x a year and after 3yrs, it's still tightly adhering to the block. Yamaha added an anode to the tstat housing in later motors than mine, which I installed, so that should help. Really bad design/ materials selection.

Interesting.

How did you add the anode?

[fairdeal]

I suspect Ollie has a "D" (2005) or earlier F200 or F225

with the introduction of the 3.3 F250, Yamaha modified the thermostat cover to add an anode

and then used the same part on subsequent F200/F225 models as well.

I have updated my F225txrd -

although skeptical that the anode offers protection to the block, other than while running with the thermostat fully open,

In my experience, the damage occurs when the thermo cavity becomes packed with wet "salt" - and then sits for weeks/months/years

[pstephens46]

I suspect Ollie has a "D" (2005) or earlier F200 or F225

with the introduction of the 3.3 F250, Yamaha modified the thermostat cover to add an anode

and then used the same part on subsequent F200/F225 models as well.

I have updated my F225txrd -

although skeptical that the anode offers protection to the block, other than while running with the thermostat fully open,

In my experience, the damage occurs when the thermo cavity becomes packed with wet "salt" - and then sits for weeks/months/years

Yes. As soon as I pulled the tstat I saw the salt plug on the side of bore. I knew I was screwed. Chipped it away and sure enough a pit underneath.

I was serious about not needing the entire quart of Alodine/Bonderite. You are welcome to it after I finish my small project.

[fairdeal]

this is the original 3.3 thermo cover



and the improved design

I was serious about not needing the entire quart of Alodine/Bonderite. You are welcome to it after I finish my small project.

thank you! perhaps we could work that out somehow. The "hazardous shipping fee" that is more than the cost of the product has kept me from ordering it....

[99yam40]

yea even my C40 had the salt bridge at the stat eating away at the block.
only copper I saw was the temperature sensing center part
ended up having the hole welded from the outside and then used JB weld to fill in the big pit on the inside after cleaning it up the best I could

[driver27]

Will the revised cover work on the 2005 and earlier F225s? Is the group consensus that it is a worthwhile investment?

Thanks

[ollie366]

Fairdeal is correct, I have a 2004 F225. I found the part # for the housing w/ anode for a 2006 motor and found them in ebay. I'll see if I can find the part # and post it. Tight fit but it does bolt right in.

[ollie366]

The part # is 6P2-1240H-00-9S. On ebay for about $60 ea delivered

[robert graham]

this was the worst of my thermo housing corrosion - prior to thorough cleaning down to shiny metal





this is after painting with zinc chromate (actually the other thermo housing)

It looks like that should work very well.....

[panasonic]

http://www.aircraftspruce.ca/catalog...SABEgJsofD_BwE

http://www.aircraftspruce.com/catalo.../alumiprep.php


We had this discussion before. The first product is alodine and the second is alumiprep 33.

When you read the instructions for the alumiprep 33 it will say not use on castings or high copper content aluminium. I do not why it says that....i have used it successfully on cast aluminium parts before with no ill effects. It is a mild acid, so not getting it all over the place is key. And plenty of rinse water will dilute it and get rid of it.

I this case, the corrosion is down in the bore and where the thermostat sits, simply stuff a rag down the hole to catch any excess liquid. And remove after treating and rinse with plenty of water.

This is NOT a strong acid and will not go down somewhere and eat a hole through the block or anything like that...we use it all time right on the aircraft structure and use rags to catch any excess and rinse with plenty of water.....

Using both products above plus zinc chromate primer will really help in stopping the corrosion. They come in quart bottles.

Oh my post showed up after all.....see above.

Stephens do you have a General Aviation airport somewhere close by? If so, go make friends with some mechanics and ask them if they can get a you say 10ml of Alodine. Don't be shy now...just look for the scruffy looking dudes out by the door smoking and complaining a lot.....that will be the mechanics....hahaha

[panasonic]

I don't know what is going on but my original post showed up and I replied to it and again it disappeared.....I copied it this time without the links to see what happens this time. See below.


We had this discussion before. The first product is alodine and the second is alumiprep 33.

When you read the instructions for the alumiprep 33 it will say not use on castings or high copper content aluminium. I do not why it says that....i have used it successfully on cast aluminium parts before with no ill effects. It is a mild acid, so not getting it all over the place is key. And plenty of rinse water will dilute it and get rid of it.

I this case, the corrosion is down in the bore and where the thermostat sits, simply stuff a rag down the hole to catch any excess liquid. And remove after treating and rinse with plenty of water.

This is NOT a strong acid and will not go down somewhere and eat a hole through the block or anything like that...we use it all time right on the aircraft structure and use rags to catch any excess and rinse with plenty of water.....

Using both products above plus zinc chromate primer will really help in stopping the corrosion. They come in quart bottles

[zenoahphobic]

Anybody ever thought to paint the thermostat frame, as it closes the electrical with the salt bridge plug. Takes two dissimilar metals to tango.

[TownsendsFJR1300]

I click the "like button" for the last two posts and it shows "unlike"... ???