Coolant overflow resevoir not draining back into radiator

[Anthrax]

I'm not having overheating problems and the resevoir is not overflowing or anything crazy but it is staying rather full and not filling my radiator back up. Anything I can check to figure out why that's happening? Tube that connects the 2 is good. Head gasket was replaced a year ago and no other symptoms that points to that.

99 4runner

Thanks

 

[nissanh]

Simply clean the reservoir cap and the tube attached to the radiator. Those two can get clogged. When did you last flushed the coolant system?

 

[19963.4lsr5]

The rad cap allows expanding coolant to push into the expansion tank. When hot coolant starts pushing past the cap the heat seals off the vent.

You should see a slight rise and fall of the level if the cap is behaving properly. Plus there should be no air pocket under the cap.


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[4Runner fun]

check the cap, and the hoses going into the reservoir, it's like a straw, if it can't create a vacuum as it cools to suck water back in it won't. and is your overflow good no holes in it and are you loosing coolant?

and is the coolant level high enough to be drawn back?
just some things to check

 

[phattyduck]

If the hoses aren't clogged - how old is the radiator cap? The return valve side might be stuck. Go OEM on the radiator cap if you need a new one.

-Charlie