85 Toy 4Runner coolant loss problem

Is the toyota running hot or do you just notice it blowing coolant out of that hose into the reservoir ????

Check water pump or may even be bad head gasket as a last resort

Is the water circulating?

Sure sounds like a blown head gasket...look for milky brown gu under the oil cap and occasional water out the tail pipe, lag on starting

Sound like you need to change your t-stat (thermostat) sounds like its stuck shut.

Well , I am leaning toward your head gasket going.
What is happening is the coolant system (all new I see) is pressurising to the point of blowby .

My recomendation is to NOT put the cap on all the way (ie; 1/2 a turn loose) to allow the pressure to escape w/o exhausting the coolant in the process.

First Check if coolant level is proper, The small hose is used to allow the OVER FLOW to exit system.

1. Is the vehicle overheating? or is there a small amount of fluid being discharged from the hose. When the coolant gets hot it expands.

2. If the fluid creates a loss large enoughto allow overheating, then I would look for a blockage in the coolant system. Keep me post with your progress.

Head gasket