I have an aluminum thermostat housing, it has quite a bit of pitting and corrosion on the sealing surfaces and also where the radiator hose should clamp. I am thinking of finding some way to "deck" the sealing surface, but I can't think of a way to repair the pitting on the hose outlet. Is there a way to repair aluminum? If it was steel I would fill and grind, but I don't know much about aluminum. It would be easiest to just replace the part, but Cat wants $700 for it
Part number?
9Y2587 Thermostat housing off a 3406C. It is the inner housing, the part that bolts to the block.
I would grind it out clean leaving the surface as rough as possible. I would then fill the pit with an epoxy such as jb weld. It could be welded up if you know a good aluminum welder.
^ that pitting is a manufacturing defect. It will not fail further if you clean it out as he said. If you want it smooth the epoxy will do it. For decking it, I clamp things like that in a vice and use a brand new 12" file on them. If you have a steady hand you won't round the corners appreciably and it will produce really flat results.
Touch up that mating surface on a larger disc sander. Just hold it flat against the abrasive.
The pitting was too deep to sand with a disc and have a good flat sealing surface afterwards. I ended up sending the piece to a machine shop, they decked the mating surface down and welded the pitting on the radiator hose outlet and then re ground it. It came out nice and cost about $200.
Epoxy-That's what is used to fill lower liner bores that are pitted in a Cat block. Done many that way never had a issue leaking past liner o-rings. So it will work for that too. Make sure to anti seize the entire length of those mounting bolts, or cover with moly. Even though you already completed it.