[chiphead]

Reviving this thread

I've got some brown sludge/silt in the radiator. I've flushed it twice now and its come back again. New aluminum radiator, water pump, etc. The engine sat with the intake off for some time before I got it. It looks like some squirrels may have hid acorns in the head's water inlets, because I've found bits of acorn in the radiator. But mostly it's rusty coolant. It runs cool around town but builds heat on the interstate.

What's the best way to flush this out with the engine in the car?