coolant reservoir?

[toad]

ok, i've searched five pages under 'coolant' and i can't really find an answer to this question:

what function does the coolant reservoir provide?

what i mean is, the manual says to make sure the reservoir is between the 'low' and 'high' lines. it says to add directly to the reservoir. however, i read where some people put coolant directly into the radiator cap. does the reservoir store coolant that needs to escape the radiator or does it hold coolant that the radiator needs once it runs out of what is in the actual radiator?

i know this sounds like a fairly basic question, but i just filled(actually 'over-filled') the reservoir and was wondering if this will harm the engine in any way? it's a good 3 inches or so over the 'full' line, but still not to the funnel-part of the reservoir. it was kind of dark in my garage and i didn't see the level until it was too late. also, why not just put coolant directly into the radiator instead of a reservoir? btw, i'm using the official toyota long life stuff. thanks!

[detroiter]

You won't harm the engine at all by over-filling it. What will happen is when your car heats up completely to full temperature, that excess coolant that is above the full mark line, will be taken out of the system by a excess fluid dump hose. basically runs out and
dumped from the car.

So if their's too much in there, it will make itself right.

[jaime]

Shouldn't cause any problems. Worst that can happen is that if your engine ever gets very hot, the coolant in the radiator will expand and increase the pressure inside the radiator. The radiator cap will let some of the coolant escape to lower the pressure. The coolant that is released goes to the reservoir. If the reservoir has too much water/coolant, it will overflow and spill coolant. As the coolant temperature goes down, the pressure decreases and the radiator will be refilled from the reservoir.

EDIT: Dang! Detroiter beat me. Basically saying the same thing but in easier to understand terms. :)

[toad]

thanks! i knew there was some sort of 'give/take' relationship between the reservoir and the radiator, i just didn't know how it worked. i feel better now knowing i haven't done any serious damage to the wife's car.

one other question: her car has almost 100,000 miles on it now. do i need to drain the radiator and refill it with new coolant or am i fine for now just topping-off the reservoir? i realize that i'll probably need at least another jug of coolant to do the flush, but i don't want to spend another $22 if i don't have to. if i do refill the radiator, am i just pouring directly into the cap and how do i know when i've filled it properly? thanks again!

[Hershey]

The coolant resorvoir for our 2010 3 door came 1 and 1/2 inches over the FULL mark from the factory . Still is . Pointed it out to a TOYO service manager and he said that it won't cause any harm to the car . Hopefully he's right . Hasn't run over as of yet , has seen 90+ degree days .

[Hershey]

Might want to get it flushed . If you do , try to remember to have the heater set to HOT position ( all the way to the right ) so the coolant in the heater core is flushed out as well .

[Focus_Sh1ft]

ALWAYS put coolant into the radiator first. After I had turboed my car and leaked out a ton of coolant, I poured it into the resevoir tank only. I'm not entirely sure why, but my car continued to overheat and didn't appear to be taking enough out of the tank. Gotta love learning the hard way

[toad]

Originally Posted by Hershey

Might want to get it flushed . If you do , try to remember to have the heater set to HOT position ( all the way to the right ) so the coolant in the heater core is flushed out as well .

i'm assuming this is done with the car off, right(something about reaching under a running car doesn't sound right)? where do you take the flushed coolant? i'm sure down the storm drain isn't a very safe place to do it
thanks again, again!

[Hershey]

Take it a TOYO service center for flush and fill . Put the heat control knob all the way to the right for the hottest setting when you arrive at their lot so the heater core gets flushed as well .

[rye7jen]

Just a quick Q, is it ok to top off the reservior with a distilled water?

[RedRide]

No, because eventually it will dilute the whole cooling sys.
Just top it off with 50-50 Anti freeze-coolant/water mix.

BTW, distilled water is not nessay in a cooling sys.
Also keep in mind that a proper AF-coolant/water mix is nessary even in a hot climate as AF wiil raise the boiling point of the coolant, provide anti corosives, and enable better heat transfer.