Is it critical to change coolant at 100K?

[voxtrot]

Originally Posted by tmontague

Do it yourself in the parking lot - here's how:

Buy a large oil drain pan (or equivalent plastic container) and slide it under the front of the car where the drain petcock in on the bottom drivers side of the rad. Look for a yellow plastic knob, you can reach it from the top of the engine bay. It may be stuck but be careful because you can break it.

Drain the coolant out from this pet cock (remove rad cap to speed this up and make sure coolant is not hot!). This will take 20 mins or so to fully drain, but once it stops draining close the pet cock and re fill with fresh Toyota coolant (50/50 mix) from the rad cap.

Fill until it over flows. Then squeeze both the upper and low rad hoses a few times and if the coolant level drops at the rad cap, re fill until it is at the top.

Keep the rad cap off and start engine. The coolant level will drop, refill it again until it is full and put rad cap back on then turn off engine. Make sure your overflow reservoir is full of coolant to at least the F line if not more.

Turn the car on and go for a drive. 20 minutes in current temps should be enough to get coolant up to operating temps, go for a jaunt on the highway and back.

Get back home and park the car. Check the coolant level in your overflow reservoir, it likely dropped some. Fill it back up to the F mark. Once your coolant is cool enough, remove the rad cap and if the coolant is not at the top then fill it to the top and replace the cap.

Drive the car as your normally would over the next week but after every day check the overflow reservoir and refill it so it is at the "F" mark. After a week of this you no longer need to keep checking it.

The yaris burps the air out of its cooling system very well by itself as the fill neck is properly situated as the highest point in the system. As it burps air itself it will pull coolant from the reservoir tank which is why you need to check it after you drain and refill the system.

Your only potential issue may be needing to use pliers on the drain petcock valve to crack it open. It is easier to do from under the car but can be done from above. Just be cautious not to crack it. Warmer temps help keep the plastic more pliable.

You can easily drain the overflow reservoir by removing the small diameter hose from the radiator fill neck. Once it is removed lower it in the engine bay so that is points into your drain pan. Once it is lower than the outlet on the reservoir, coolant will automatically drain from it.

Hi tmontague I am going to be doing a coolant drain and flush and replace the thermostat on my 2007 Yaris Sedan with Automatic Transmission for the first time. I just recently hit 160k miles and I do not think the coolant has been drained and filled before I bought it used. I am going to be USING THIS
with distilled water. I will buy two gallons to flush or more until it comes out clear. Once it is clear how do you know how much of the concentrate to add with the clean distilled water already inside? Manual says 5 Quarts for Auto.
I don't know if everything comes out in the flush so do you have to wing it a little when adding the rest? Since it is hot here now would it be ok to have a little more distilled water inside radiator or reservoir? I don't want to damage the coolant system or engine since this is my first time doing this. Also worried about the left over air pockets damaging system after.

Thanks