How to clean out water pump housing?

[sixpack_sid]

I just bought a used water pump housing from a junk yard and it's pretty rusty inside & out. I plan on sandblasting what I can see, but how do I clean the inside? Also, when it's cleaned up, do I paint the inside or leave it bare metal?

[terrible one]

I would get some Evapo-rust and soak it in it for 24 hours. You'll be amazed! 

[FLG]

Muriatic acid works wonders, mixed it 1:1 with water or even 2 parts water (remember to add acid to water)

I recently did a 1:1 mix in my moped gas tank and the damn thing came out clean as a whistle, only took about 20 min.

Paint the outside leave the inside bare.

[sixpack_sid]

Muriatic acid works wonders, mixed it 1:1 with water or even 2 parts water (remember to add acid to water)

I recently did a 1:1 mix in my moped gas tank and the damn thing came out clean as a whistle, only took about 20 min.

Paint the outside leave the inside bare.

I wish I would have taken "before" pics! I can't believe how clean this thing got! It was SO CRUDDY and RUSTY I didn't think even sandblasting it would get it clean! I dipped it in the muriatic acid for 30 min and it is IMMACULATE! It looks like new! I painted it right away-it's so rainy and damp here I was afraid it would start rusting. I'll let it cure and put the pump on and bolt it up.
Thanks so much for the advice! I would've been blasting that housing for HOURS and not gotten the results I got with the acid!

[FLG]

I may have made a bit of a error, completely forgot to tell you to neutralize the acid by dipping the part in vinegar and/or baking soda mix

I highly apologize for that error 

[nrt69]

i sandblasted the outside of mine....not a good idea. you can hear sand grinding inside....even after soaking andflushing it.