zd30 coolant reservoirs

[rotor138]

Why does the Patrol have 2 reservoirs? I overfilled (topped both to the top as well as radiator) the bottom one the other day and since then it has been overflowing down through the passenger side wheel arch.

Having replaced the heater core today I'm going to flush all the coolant from the car including removing the two reservoirs and couldn't workout why it has the 2 reservoirs.

[mudski]

One is an expansion tank and the other is a recovery tank for when the expansion tank gets low. Plus you don't need to fill them to the top, only to the line markings on the sides of the tanks...

[healy]

dont fill both up they have fill lines top and rad take water and coolant and bottom you fill with just coolant to fill line

[alexx]

Both are reserve tanks. They are connected in one way or another the patrol being having only one water pump. If your car got an intercooling unit, that must be the reason why 2 reserves. A big-sized tank may be difficult to position in the engine bay.

I do add only radiator coolant to the other reserve as it is instructed, only within its limit. Min-Max indicator is provided in the tank. The intercooling unit draws fluid from this.

The main reserve tank is always filled to its brim. It feeds fluid primarily to the main radiator.

[Lieney]

As stated. You can have a surge tank that holds excess water for high, or sudden higher rpm. the other is a Overflow to supplement it.
Hot water takes more room than cold, So it will spit some out when hot,
Hence the fill lines.

[rotor138]

Not much room in my engine bay so didn't notice the fill lines until it started leaking out when hot. It was the first time I put water i that bottom tank in the 5 years I've owned the car.

Does the top tank have fill lines or is it just fill it to the top?

Will hopefully get round to draining and flushing the system tomorrow before connecting the new heater core back into the circuit.

[a_namora]

just fill up and stop when it's about a knuckle from the lid, that's about a max fill line i think. That's what i do when can not see the max line