What is this sand in my coolant ?


Hey guys.

After I changed brake and clutch fluids yesterday, I decided today to flush my coolant.

Here is my concern - after I flush with water, I always see yellowish sand or sand-like particles in the flushed water. I flushed five times already and the water is clear but everytime I would see sand.

Is this normal? Should I continue to flush until there is no more sand?

Your help is greatly appreciated. Thank you.
It's normal, just do a good job when you flush out the bottle...also you should only use distilled water with your coolant :beerchug:
We've all encountered this phenomena to one extent or another. Never gave it much thought though, just cleaned my overflow, flushed my system, thoroughly and went about my way. Could be plastic "yield" from the inside of the bottle migrating around the system, could be assembly residue from original machining.......as long as it isn't clogging the radiator, or jamming the thermostat, I don't give it much thought. Mine runs fine ! :super:
I was noticing there looks like about 1/4" of something collected in the bottom of my coolant overflow bottle. Bet it's the same stuff.
Ok,thanks guys for all your inputs. I was just worried about clogging the radiator or worse the water pump.

The thing is, when I take a small amount of this "sand" in my palm and squish it with my fingers, it's soft and feels like clay or wet dough.

Thanks again.
Calcium build up which is very normal in aluminum radiators. That's where the distilled water helps.