Radiator Rust

I have a 91 mustang 5.0 with rust in the radiator. I’ve taken it in twice for and acid bath and have replaced the hoses & thermostat. Needless to say I still have rust. What can be done to rid the rust from the motor? An empoyees grandfather stated I could mix water and diesel fuel together and run it thru?

Have you replaced the radiator? While if I understand correctly the rust is coming from the engine, getting residue out of all the cores and the bottom tank may not happen easily.

You realize also that acid baths do not eliminate the cause of rusting, they only remove the surface rust. If the material beneath the rust is oxidizing (it is-that’s where the rust is coming from. Rust is iron oxide) the problem will just return anew.

Or am I misunderstanding the post. Are you acid bathing the radiator?

By the way, don’t do the diesel fuel. You’ll probably just create other problems. The cooling system components are not designed to be bathed in diesel fuel and it just may affect plastics, gaskets, and elastomeric seals.

Please tell me your running coolant, not straight water.

You need to flush the engine block. This is where the rust is coming from. You need to use a chemical flush, and keep flushing until the water runs clear. Then drain and fill with a good glycol-based coolant mix at 50/50 with distilled water. I used Prestone Super Flush with good results on a 5.0L Ford V8 that had rusty coolant.