Radiator top up??

[GhostMan]

Hey all

This may seem a stupid question...but where / how do I top up the radiator on a RAV4 T180? I take it that it is not the same tank that the coolant goes in to (the expansion tank)?

If someone can point me in the right direction that would be great.

Cheers

[philip42h]

If required, you would top-up the coolant via the cap on the expansion tank - it then flows through the engine, water pump and radiator etc.. Don't top-up the coolant unless it is below the minimum level when the engine is cold. Topping up to the maximum mark may well be self defeating as coolant may then be forced out as it expands when hot. If it has found a comfortable level between max and min it's probably best left well alone.

[Byzii]

Phil actually raises a good point about coolant top-ups. I don't know why but almost all manuals always say to fill the coolant when car is completely cold up to the max marker. What ends up happening is when the car reaches its operating temperature the coolant will expand and everything above the max line will get ejected through the overfill tube.

Usually in order to get the coolant level to max marker when the car is hot, the level should be just about between min and max when completely cold.

[yossarian247]

1 hour ago, Byzii said:

Phil actually raises a good point about coolant top-ups. I don't know why but almost all manuals always say to fill the coolant when car is completely cold up to the max marker. What ends up happening is when the car reaches its operating temperature the coolant will expand and everything above the max line will get ejected through the overfill tube.

Usually in order to get the coolant level to max marker when the car is hot, the level should be just about between min and max when completely cold.

Most manufacturers take account of that though. The max line is drawn at the point at which the coolant should be when cold. It doesn't matter if the coolant goes above that line when hot and nothing will be expelled unless there is a leak or a faulty cap. 

[philip42h]

51 minutes ago, yossarian247 said:

Most manufacturers take account of that though. The max line is drawn at the point at which the coolant should be when cold. It doesn't matter if the coolant goes above that line when hot and nothing will be expelled unless there is a leak or a faulty cap. 

What Nick says is very true - provided that the level does not exceed the maximum mark when cold, coolant should not be expelled as the temperature rises. That is, after all, precisely what the expansion tank is there to do!

Being pedantic, when cold the level should not exceed the maximum mark nor fall below the minimum mark - any where in between is just fine. Folk do at times get rather obsessed by filling to the max which isn't necessary at all.

There is some anecdotal evidence of diesel RAVs finding a natural level that is some way short of the maximum mark. Quite why, I don't know - possibly the cap doesn't seal as well as it should.  Repeatedly topping up to the maximum mark can prove self-defeating. Topping up with water will progressively dilute the coolant. It goes without saying that one should top-up with a correct coolant mix.

[gjnorthall]

There are two types of system - one where the expansion bottle is pressurised - the other unpressurised. Pressurised bottles are often quite large in volume and the variation in level between hot and cold is relatively small. Some unpressurised bottles are ridiculously small and will overflow if filled cold to the max mark. The only constant is the bottle level at normal engine temperature so having the level at the max mark at normal engine temperature is the most accurate way of  regular checking  and at the same time ensuring that the cold level will be well above the min mark.

At each service - remove the pressure cap and ensure that the coolant is brim-full. Air in the cooling system is detrimental and can have an effect on expansion tank level on an unpressurised tank system.