Putting coolant directly into radiator?

[sporttrac187]

I had a coolant leak on my 2008 Sport Trac where it was spewing coolant all over the floor. I had a small leak in the radiator fixed and the water pump completely replaced.

I check the big white reservoir constantly to make sure the coolant is full, but the mechanic told me what I really need to do is check the radiator when cold to make sure it is full with coolant. If not, pour the coolant directly into there, and not the reservoir.

Is this correct? Is it okay to put coolant directly into the radiator? I was only doing it to the reservoir.

 

[rmcalis]

Yes, it is fine to fill the radiator when it is cold. The reservoir is really just an overflow tank which catches the fluid when it gets hot, expanding out of the radiator. Likewise it allows fluid to return to the radiator when the fluid gets cool and contracts putting the system is under vacuum. Continue to monitor the fluid level in the reservoir.