Hi everyone,
This is my first post, I had a 2002 4runner 2WD, it had 23k miles, The coolant in the white plastic container was half level between Hi and Low when the truck is new, now no more coolant in it. The coolant in the radiator is full.
Is this normal to lose some coolant after a while?

 

My '95, every now and then drinks some coolant. Coolant is a mixture of 2 or more substances; ethylene glycol or propylene glycol and water. The mixture has it's own boiling point and can boil off or vaporize.

As your engine gets hot, the coolant expands inside the engine. Since it now has a larger volume of coolant than what the engine and radiator can hold, the excess volume of coolant pushes out the overflow valve and is caught in the overflow tank. But the coolant will still be hot....and as such will have a higher vapor pressure and some will evaporate.

On my 3.0, everytime I see the coolant in the overflow needs refilling, my first thought is that my headgasket is leaking and soon I'll have to drop a couple grand ($) on a new engine. Your 3.4 headgaskets are much more reliable. Just refill the overflow tank with the proper mix of coolant (Toyota) and water and watch it. Your probably low because of evaporation.

 

Thanks GWHAYDUKE,
Your infos helped me to understand the reason of losing the fluid, I will fill it up as need.

 

No problem. You shouldn't have to fill it up very often. I did mine about 3-4 months ago...probably time to check it again.