What causes rust in radiator?

[sidewayzisbest]

I flushed it out maybe a month ago and now its back to rusty as hell ..and crap in it.......i used a napa powder that you mix with water when i flushed it last time....is there something wrong??thanks

 

[Look Its Aaron]

Well don't assume that some powder or any gimmick products will work all the time. Remember there is buildup in the heads/water pump/block also which is probably breaking up.

 

[Michael Yount]

As LookIts said above - you've got 13 years worth of corrosion going on inside the engine; minerals in the water (if distilled wasn't used) that get deposited inside the block and the radiator, and you can even get some galvanic corrosion of the radiator on top of all that. Given all that - you should probably keep flushing regularly until you start to keep it clear - and then it's probably time for a radiator replacement unless that's been done recently. I only use distilled water in the cooling system to minimize mineral deposits. If you've ever looked inside an old water heater, that's what happens to the inside of your radiator over time - significantly reduces it's heat transfer abilities.

 

[1970 slantroof]

You might try an inline water filter. They go in the upper radiator hose and catch a lot of junk. It will eventually clean all that stuff out. I can't remember the brand but some of the Mustang aftermarket catalogs have them listed. My buddy put one on his Cougar Eliminator and it cleared his coolant up.
Howard

 

[1970 slantroof]

Gano Filters, Los Altos, Cal. is the one. They are clear so you can keep track of the condition of them.
Howard

 

[sidewayzisbest]

thanks i think i might try that i just flushed and and i put my hand it there and rubbed the sides and my finger was covered in rust =(.......its a 4month old radiator just a stocker replace from autozone.....could this cause overheating b/c my car will be at 210 with a mark8 fan and the stock 2 core thanks

 

[1970 slantroof]

I would think the radiator would have to be pretty well plugged up to cause it to overheat on a new one like that. You could have the system pressure checked and they have a dye you can put in the radiator that will change color if exhaust gas is present. That will give you some info on your head gaskets. I know nothing about the Auto Zone radiators and whether they are equivalent in capacity to the stock ones.
Howard