cast iron water pump housing?

[sodafeld1]

I am successful at stripping rust with either evaporust, molasses and kbs powder.
I plan on using rust bullet for the housing. Should and can I paint the internals of the housing too ? (not the actual propeller, got a new aisin for that)

I know the anti rust in coolant should mitigate internal rust, but a surface kind of makes sense for longevity.

 

[Felde]

I wouldn't paint any surface that is supposed to either seal or be in contact with the coolant.
Coolant, although being solubed in water, is a chemical. You have no indication whether the paint is resistant to that chemistry.
Also you have no indication how good the paint will stick with the surface, considering the thermal conditions and constant abrasion by the flow.
If flakes of the paint come off, they would cause all sorts of trouble, clogging any small fluid line.
That could even blow up your engine due to local overheating, I think.
Cheers Ralf

 

[sodafeld1]

good point, thank you