Dirty Coolant?
 

Checked my fluids today...and my overflow tank is empty and really dirty. I put in some coolant and it turns really brown.

What could the brown stuff be? It does not look like oil. It just makes the coolant turn from green to a nasty brown.

In engines the use dissimilar metals (like ours) it is common to see the coolant turn some funky colors when it is neglected. Your engine likely needs a through flush as it has not been maintained properly.

Unscrew it and remove it and clean it!

Our cars tend to just do that sometimes... change the coolant.

the brown stuff is a mix of corrosion and acidic antifreeze that has come into contact with the iron housings. you need to flush that crap out until it turns clear again. might take a few turns until it gets clean.

Has anyone found a good way to clean out the overflow tank? Mine seems to be gunked up pretty bad and I can't get everything. Tried putting some engine-degreaser and it work decent, but I still have this brown sandy gunk shit in there..

try filling it with little rocks and fill with water and degreaser then shake it up rocks act like a sander and scrubs off that grime hope this helps

Hah that's actually pretty creative, I'll try it out tomorrow.

lol...thats freaking genius...

would you think that a buildup of that gunk would send the "add Coolant" light/buzzer? cause i got that problem too [dirty coolant]

If your coolant is dirty you need to replace it. The add coolant light turns on when there is air in the system. Assuming your car has no leaks you simply need to remove the air from the radiator. Try searching "burping the radiator" or something to that effect.

actually on this topic, I have somewhat the same problem..

it seems my thermostat housing is leaking so I got a new one + radiator cap on the way, but my coolant buzzer also likes to come on when the car is not on level ground (I.E kind of leaning to the right or left), can anyone explain that?

also, is it normal for me to NOT see any coolant in the filler neck? or does that mean something is wrong, because a bit ago I was able to add almost a whole water bottle (not jug) full before I was able to see it again.