sludge in bottom of koyo radiator??

[USMCgetsome]

So i pulled out my koyo and drained it to find that the top part had good green coolant and the bottom remaining had brown crap and after i cleaned it all out i purged the radiator and shot water through it and to my surprise i found 2 small rust chunks which were solid then i touched it and it crumbled.

what was it is this a sign my water pump is failing?

any suggestion?

[Joe]

could just be crap that was in the system when you did the swap.

first time draining coolant since then?

[Slo_240sx]

Not necessarily. Its probably just deposits that where in the motor before you got it and worked its way to the bottom of the radiator. I wouldn't worry about it unless your whole radiator is full of it. I'd flush the cooling system just to be safe and make sure to get all of the crap out.-Alex

[USMCgetsome]

gentlemen thanks for the responses. I'll ensure i flush the system. yes this was the first time i changed since the swap. But the engine has probably seen about 75-100 miles of driving in 6 months.