Coolant goes to reservoir but not back to radiator

MOguy

Explorer
I have a 2004 4runner v6. The coolant flows into the reservoir but not back to the radiator. I got a new radiator cap from a Toyota dealer and it is still doing it.

Would a bad thermostat cause this?
 
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XPLORx4

Adventurer
How did you determine that coolant flows only one way? Does the radiator consistently get low, and the coolant reservoir overflows?

Check to see that the hose isn't pinched or crimped, and that it reaches the bottom of the reservoir. Also check for leaks in the cooling system. You might also try removing the radiator cap and the reservoir cap so that you can blow air from the reservoir tube to the cap. If air doesn't flow easily through the tube, there is some kind of kink or blockage. Lastly, check the for any holes in the tube going from the cap to the reservoir.
 

MOguy

Explorer
How did you determine that coolant flows only one way? Does the radiator consistently get low, and the coolant reservoir overflows?

Check to see that the hose isn't pinched or crimped, and that it reaches the bottom of the reservoir. Also check for leaks in the cooling system. You might also try removing the radiator cap and the reservoir cap so that you can blow air from the reservoir tube to the cap. If air doesn't flow easily through the tube, there is some kind of kink or blockage. Lastly, check the for any holes in the tube going from the cap to the reservoir.
Thanks
 

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zolo

Explorer
Blown head gasket will do that. Gases in the cooling system will boil the coolant and it will over flow the reservoir tank and boil over there also.
Id pressure test the cooling system and also test the coolant with a test strip for gases in the coolant.
 

MOguy

Explorer
Blown head gasket will do that. Gases in the cooling system will boil the coolant and it will over flow the reservoir tank and boil over there also.
Id pressure test the cooling system and also test the coolant with a test strip for gases in the coolant.
Wouldn't I have coolant in the oil or coming out the tail pipe? What other symptoms?

What do i look for from a pressure test?
 

calicamper

Expedition Leader
Check the Niple at the radiator neck I've seen them crack and suck air instead of coolant. Also for a few yrs some Subarus had strait cut hoses in the over flow can and they would suck to the bottom of the can and cause this. A 45 angle cut on the bottom of the hose fixed that stupid problem.
 

MOguy

Explorer
coolant leaking into the motor, cylinder #3.

I am really disappointed. I expected a longer life from a Toyota.
 
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