Rb26 Coolant Q

[endless]

Quite sure this is normal, but just want some confirmation for peace of mind really

After idling the car for about 20 minutes my top rad hose is hot but bottom is cool to touch. Whilst idling, never goes over 81 degrees.

Is the cooling system so efficient at idle temps that the thermostat only opens slightly (causing flow to not be too high) which would result in the above scenario?

When i feel the radiator only the top say 1/3rd of it is hot, decreasing in temperature as touch the lower section.

And before anyone jumps to conclusions - brand new waterpump, thermostat, rad cap, flushed radiator. It has NEVER overheated while driving, after a drive the bottom pipe (and bottom of radiator) are hot to touch.

[tiberis]

Pretty sure thats how car radiators are meant to work, plus it's basic laws of physics.

the top part of you rad will be hotter than the bottom simply because heat rises. so thats perfectly normal.

you need that difference in temperature because then the engine can take in cooler water from the bottom.

the top hose will be hot because that the out from the engine (again, heat rises so it makes sense for it to be the top one).

i would imagine if you gave the car a good hard drive you may find that more of the radiator is warm to the touch as the cooling system is being used closer to capacity.

[JonnoHR31]

nothing to do with heat rising. top is hotter because its the outlet and its designed that way so you still get coolant flowing around if the radiator is only half full

but yer, sounds pretty normal