Hey!

On my 92 SR5, I'm getting ready to install a new Aisin water pump with metal / rubber gasket but I'm concerned about the casting surface on the block as it has some pitting, assuming from previous gasket material (paper and liquid). Should I use some Permatex on this as well? I can only assume it will leak otherwise. I did wire wheel it as best as I can, as clean as it will get without sandblasting

Thanks!

Yes, I do plan on flushing the system well and replacing with red coolant

 

I'd degrease the surfaces with acetone and install the pump using a skim of Permatex Ultra Gray sealer and omit the gasket entirely.
It is always a good idea to pass a flat file over the pump mating face to ensure that there is no metal flashings or bumps that would prevent the new pump from laying down perfectly flat and true.