Changing coolant. Anything to take care of?

[ViR2]

I want to change my coolant before spring. I've bought 8liters of red coolant. Right now there's unknown green coolant in the rad. So do I need to take some special notice before changing? As I understand, I just need to loosen that lower radiator bolt, and then fill it with new coolant, right? Or do I also need to find drain plug in the block?

Is there anything bad if I'll mix some green coolant with some fresh red one?


P.S. I did search on coolant change, but came up with nothing, so I started a new thread.

 

[starscream5000]

Flush the green out with water (running water hose) while letting the engine run to pump the fluid out completely. Turn it off, then put the new in .

 

[jdub]

Change the thermostat

Keep in mind the flush Chris is talking about will not happen until the motor is warm enough to open the thermostat. If you want to speed things up, you could just remove the old thermostat, re-install the housing, and flush with no thermostat installed (motor running). When done flushing, install the new thermostat and new gasket and fill with coolant. You want to run a 50-50 to 65-35 mix of coolant to water, depending on how cold it is.

Also, check the condition of your hoses...upper/lower rad, the small hose at the back of the head, and the small hose just behind the water pump housing. Might want to check your heater hoses as well.

 

[starscream5000]

Long time no see John , I can finally post at work again! I had also realized that after I posted, but I'd figure he'd at least know how a thermostat worked (or he'd find out soon enough ).

 

[jetjock]

Not sure what "red" means because coolant color is nothing more than dye and is meaningless these days. I'll assume you're talking about Toyota's phosphate based coolant. The green is likely silicated coolant so as mentioned it's best to get it all out because it's not wise to mix coolant chemistries. If I were you I'd drain the block and use distilled water with the coolant for the final fill.

Good time to replace the t-stat if it's age is unknown. I prefer the Stant Superstat over OEM. Maybe change the cap too. You may need to purge air from the system afterwards since I'm also assuming you can't do vacuum filling. Too bad, because it sure makes things easier and leaves zero air in the system to cause grief.

edit: The dubster beat me to it

 

[ViR2]

No coolant is not Toyota's, its manufactured by Sunoco if that changes anything I've also changed thermostat before parking Supra for winter.
One thing about purging air, is it necessery to do something special for that? From my understanding it will purge automaticly through overfill reservoir, or am I missing something?

 

[starscream5000]

That's the way it's "suppost" to, but a lot of our supras, if not properly maintained in the coolant area, don't do it or do it very slowly. You can jack up the front of your car really high, until the tip of your muffler is almost touching the ground. Run the engine until the thermostat is open and "burp" the air out through the rad cap.