Every time you drained and filled the radiator with water reduce the amount of coolant left in the system (which was in engine block) by half... too much math to deal with, just do it all over again. if you drained and filled 3x and it already had 50/50 then there was, before adding new radiator full of the 50/50.. .... ugh, make my brain hurt.
brown or rust color can also mean someone mixed green and red.
Do it again and drain from engine block petcock this time. Or drain radiator and add full strength.. Water does a better job of cooling but it freezes... the coolant is to prevent freezing and its for preventing rust and corrosion. Its cold, so it would be okay to be running too much coolant. better to be running too much than to little and have the block freeze. if you have the money, i'd just do it all over again.
straight coolant will not absorb the heat as desired so that is a bad idea. in addition to that, waster alone freezes at 32 degrees f, and at 0 degrees c, simple science there. coolant/antifreeze changes both points of concern. your tester may be at fault or your mixture could be off a bit. 50/50 is ideal in most situations but for a stronger resistance to freeze or boiling, you can drain out some and add only coolant. if you are using the 50/50 premixed stuff, that can create and issue there.
Hello
The only thing I can think of as if diluted to correct amount is that it has been diluted further.
There are 3 parts to the coolant system Engine block, Radiator and Heater system.
When you drained the coolant and flushed did you let the whole system get up to normal working temperature to open the thermostat and circulate around the heater system?
Andy C
The 50/50 mix was diluted by water left in the block, drain a gallon out and top off with straight anti freeze.
At a guess you have flushed and drained the radiator, but the engine block was still full of old rusty coolant. Now you have topped up, but only replaced ~1/2 the actual system.
Hence the rusty look, and diluted anti-freeze.
Not sure if there is a trick with that vehicle to get ALL the old coolant out.
When you flushed the cooling system and ran the engine with water you did not drain the engine block to get all the water out. We always check the cooling system capacity in the specifications page of the glove compartment manual then pour ONE HALF its capacity with 100% pure antifreeze first in an empty cooling system. Fill any remaining space with distilled water.
Never fill a completely empty cooling system with 100% antifreeze! A pure 100% antifreeze bottle will FREEZE @ +5 DEGREES!
Siphon all coolant from the radiator and coolant recovery tank. Re-fill with 100% pure antifreeze.
Test it again..maybe find another tester to try.Also, You may not have gotten all the water out of it. So it may have deluted you 50/50 mix.
I would put in pure coolant if I were you. Water can be corrosive. Plus it has a lower freezing point than water (I think).
you didnt get it all out. id drain off a gallon and add 100% antifreeze and forget about the tester
I've only had this car for a few months now, and since winters coming and it's gonna freeze soon I checked the coolent. It's was rust brown so I'm pretty sure it's never been changed. So I drained it and flushed it following the instructions on the flush, then I ran it with just water like it said to. And then put new 50/50 coolent in. But when I tested it, it was still kinda rusty looking and it only said it was good for - 18°. Which doesn't make any sense because I put In the 50/50 which is I tested for - 32°? I know that it's gonna get below - 18 so that's just not gonna fly. What's going on with it and how do I fix it? 2002 Ford Focus ZTS 150000 miles and Prestone 50/50 coolent and Prestone coolent flush
