Thermostat Bore corrosion revisited

[pstephens46]

I posted before on this topic. I replaced the tstat about 6 months ago. This morning I removed to inspect and found another pit. They seem to form beside the "shoulder" of the thermostat as it traps salt in that spot. The two pits are deeper than they appear in the photo. Would it make sense to try to fill the pits with JB Weld before painting? I wonder if the JB Weld would stay in place and prevent more corrosion in that spot? Or would a 2 part paint as suggested before be enough?

[panasonic]

I am not seeing the pit....please point it out.

If you don't remove all the corrosion, mechanically, then burn out what little bits are left over, treat the area with something to give it a protective film. Prime and/or paint. Then the corrosion WILL be back.

JB weld will slow it down slightly. Corrosion is like cancer, if you don't get it all then it will be back.

JB weld is just a filler.

[boscoe99]

Fairdeal will be along shortly. He had the same issue. What he did seems to have slowed up/stopped the corrosion.

[fairdeal]

Yep.
As Panasonic said, (although I think tooth decay is a better metaphor than cancer) the only way to halt it is to clean the surface down to bare bright metal and then an effective coating.
I would not apply a JBWeld "patch" inside fearing that rot could continue under it, now unseen.

i applied some MarineTex on the exterior over the thinned area for reinforcement, but on the inside just zinc chromate primer.
That bonds extremely well to aluminum and have stood up to hundreds of running hours. I inspect several times yearly and if eventually some small spots of paint are lost it is readily apparent.

I do have some thoughts of re- doing it with a product called I think "Alodine" which Boscoe and Panasonic are likely familiar with.

[pstephens46]

I am not seeing the pit....please point it out.

If you don't remove all the corrosion, mechanically, then burn out what little bits are left over, treat the area with something to give it a protective film. Prime and/or paint. Then the corrosion WILL be back.

JB weld will slow it down slightly. Corrosion is like cancer, if you don't get it all then it will be back.

JB weld is just a filler.

The two pits are hard to see in the picture. Up top, the lighter discolored area. Not large but deep enough to be concerning. About this alodine. Does it require an acid bath first? Is there a one step version? I see gallon sizes online.

[panasonic]

Yep.
As Panasonic said, (although I think tooth decay is a better metaphor than cancer) the only way to halt it is to clean the surface down to bare bright metal and then an effective coating.
I would not apply a JBWeld "patch" inside fearing that rot could continue under it, now unseen.

i applied some MarineTex on the exterior over the thinned area for reinforcement, but on the inside just zinc chromate primer.
That bonds extremely well to aluminum and have stood up to hundreds of running hours. I inspect several times yearly and if eventually some small spots of paint are lost it is readily apparent.

I do have some thoughts of re- doing it with a product called I think "Alodine" which Boscoe and Panasonic are likely familiar with.

Yes alodine would be good....I have mentioned that several times.

[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.

[panasonic]

Just typed a good reply and it said "unapproved".... boy that bugs me

Might try again, too tired to do it again.

[99yam40]

Just typed a good reply and it said "unapproved".... boy that bugs me

Might try again, too tired to do it again.

Have you tried clicking the back button when that happens to see if you could get it back?
If it comes back up copy it to clip board and then paste in a new post

[pstephens46]

Just typed a good reply and it said "unapproved".... boy that bugs me

Might try again, too tired to do it again.

Well thanks for trying.

maybe they could provide some guidelines so we could avoid the algorithm police here.

[TownsendsFJR1300]

I believe any links, posted here, to other web sites is an automatic cancellation.

Also, I've found if you edit too many times, after maybe the third time (fixing grammar usually), it cancels out...

[panasonic]

I believe any links, posted here, to other web sites is an automatic cancellation.

Also, I've found if you edit too many times, after maybe the third time (fixing grammar usually), it cancels out...

I had links in the post...

You can get Alodine from Aircraft spruce in quart containers.

[panasonic]

Have you tried clicking the back button when that happens to see if you could get it back?
If it comes back up copy it to clip board and then paste in a new post

I forgot to do that this time....*$^//#^

[pstephens46]

I will order a quart. If the wife asks, the answer as always will refer to safety. Cheaper than a block with a hole. She doesn't know what a block is. Other than my head.

I'll use a bit of it. A few spots on lower could use some. Fairdeal can pick up the rest on one of his pilgrimages to NJ. I live close to I-95. Maybe we should refer to him as Hemingway now.

[fairdeal]

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)