Hello, I have a 99 4-cyl honda accord and have a couple of questions. I wonder why my coolant is turning a dark brown color even after two coolant changes and two coolant flushes, any ideas? I did a combustion test and results were negative, I think the bottom of my radiator is filled with junk. Also, what coolant hose is next to the coolant sensor?
You may have a lot of rust build-up inside your radiator, which is giving off that color you can't get rid of. You may have to replace your hoses as well, which keeps washing through your system. Your coolant hose next to the sensor, may be your lower radiator hose. Never mix tap water with coolant, this excellerates the formation of rust. I suggest that you thoroughly inspect the dipstick and radiator cap for a frothy white film, if this is the case you have a blown head gasket. Otherwise, use a rust inhibiting coolant after you replace hoses, and possibly radiator.