back
on a spill or open collection pan.Changing Antifreeze Coolant
[Difficulty Level 2]
First things first: Antifreeze (straight
or diluted 50/50) is very deadly to your dog or cat! A small puddle or open
container is very attractive to them and there are constant reports of poisoning
(the wife worked in a Vet's office for many years). Please don't turn your back
on a spill or open collection pan.
Second, things second: Don't open the radiator cap when the engine is hot. The coolant will be under pressure when hot. The coolant is hot enough to scaly you. If you release the pressure on hot coolant in contact with an even hotter engine block/cylinder walls, the boiling point of the coolant is lowered as the pressure is released. Often the lower boiling point to atmospheric temperature is below the temp of the hot block and the coolant in the block wants to turn to steam (boiling) pushing all the rest of the coolant out of the open radiator cap you just removed, burning your hand and making a general mess of things. You may have seen this happen as you've passed a stopped car on the side of the road on a hot summer's day. Some dude is open the radiator cap on his overheated engine and presto - instant gieser! (actually, it is the same exact principle that Old Faithful uses to operate)
Third: Never add cold water or coolant to a really hot block. This can crack the block. That is, if you fill the radiator of an overheated engine and then start the engine the cold water being pumped into the block can actually crack the engine block. You wont be changing anti freeze in a very hot engine, so no need to worry. However, if an engine overheats on a hot day and blows out all it's coolant (or most of it) and you need to add water to refill the cooling system, add the cold water with the engine running. This will mix the cold with the hot as it goes through the radiator. Water is OK in an emergency, but replace it with the proper mixture asap. For example, if you spring a leak in a hose and loose coolant, one might consider slowing the leak as much as possible (taping up the hole well), then refill (with water), leave the radiator cap loose (to avoid building pressure that will push out the coolant), and immediately drive to the nearest service station, dealer, etc. to get it repaired and have the coolant replaced. Never run an engine without coolant.
Fourth: If flushing the radiator with water from the garden hose, never apply the full pressure of the hose to the cooling system. I was reminded once as a young boy that the hose pressure can be 50-70 lbs/sq inch. Now, since the cooling system is built for a nominal pressure increase of 15lbs/sq inch or so, 50 lbs will damage it - that is, spring a leak somewhere. Knowing all this, I was working on a Ford one day many years ago and put the hose in the top of the radiator and actually held my hand around the radiator cap opening to try to force more water out through the open valve in the bottom of the radiator as I was flushing it (with the engine running). Sure enough, I sprang a leak in the heater core behind the dash. Needless to say, 3 days later, after disassembling the dash and replacing the core, I had learned an important lesson. So keep this in mind if you are using a hose and working on the cooling system!
Here's what Lexus has to say about anti freeze (from the owner's manual):
Draining the coolant:
You can drain the coolant from the bottom of the
radiator. The system holds 9.5 qts. From the bottom of the radiator (drain valve),
you can drain about 6 quarts. The remainder is in the block and can be drained
by a valve. The AWD and 2WD have slightly different placement on the engine
block (See manual page below and photos by David S.). The photo at the right
is looking straight down at the back of the radiator. Arrow showing the radiator
drain plug.
The
drain valve can be opened by reaching down between the engine and radiator on
the bottom driver's side below the fan, there is a whitish plastic valve/plug.
You can place a tube on the outlet of the valve through the hole in the bottom
cowling and drain directly into a drain pan. Otherwise, just open the valve
and catch the antifreeze in a drain pan. Lexus recommends removing the engine
undercover (cowling) and get to the drain from underneath. Likewise, to get
to the engine block drains, working from underneath may be best.
From below, place your bucket\pan under the location
of the radiator drain valve. The position of the 
valve
is above a hole in the cowling. A plastic tube can be used to connect to the
outlet on the bottom of the valve and into a pan. Otherwise, just collect the
coolant as it flows down.
While the coolant begins to drain, open the radiator
cap to allow the coolant to freely flow.
Overflow Tank
The remaining coolant in the overflow tank can be removed by syphon or just removing the tank and pouring out the contents. Pull up on the tank, wiggling it a bit (you really have to yank on it to get it off the bracket).
Bracket holding the tank.
There are 2 nubs on the bottom of the bracket that hold the tank in place. When reinstalling the tank, you will hear the pop as the nubs pop into place.
From the manual:
Block Drain Plug/Petcock (photos courtesy of David S.)
View from the top, looking down.
View from the bottom of the engine.
Good Luck!