Major Cooling Issue.......1999 Tacoma 2.7 4X4 SR5

Please help....

I just replaced my leaking radiator this morning and now I have coolant boiling in the upper radiator hose for no apparent reason. It seems like nothing is flowing and temp started to rise and overheat, so I shut it off.

The inlet from the upper radiator hose to the block has some sort of sensor attached to it. Could this possibly be the problem? I have searched online and in my shop manual but cant seem to find any numbers or help on those two items. When I went to remove the wire it just sort of crumbled due to age I guess. Now on top of boiling coolant I have to replace the sensor that I cant locate anywhere.

I have attached two pics of the inlet and sensor.

This Tacoma is in great shape for its age, and I was trying to sell it. Any help would be greatly appreciated.

Thanks.

 

electric fan or clutch fan?

 

clutch fan

 

Truthfully the thermostat controls the flow of the coolant. Either

A) thermostat not opening up
B) headgasket issue

You'll need to get a combustion tester to confirm that its your headgasket.

 

I sure hope its not the head gasket......thanks

 

just test, you should be able to rent the tool and buy the fluid. its good to have really.

 

I say thermostat. Try replacing the thermostat.

 

I did replace that already, is it possible that I could have gotten a dud?

 

Hmm... how old are the radiator hoses? Did you flush the cooling system yet?

I would get a coolant tester and just to be safe a compression tester.

 

i will try that next, I just replaced the hoses too.

 

Would a water pump not operated properly cause this overheat?

 

A few other items to consider, does your radiator cap maintain proper pressure (may want to have it pressure tested), are the drive belts OK/adjusted properly, and have you measured the temperature of the coolant to make sure it's not a faulty gauge?

By the way, welcome to TW -- OP.

 

I haven't gotten that deep into it yet. It went from working fine to a big mess very quickly. The radiator had a leak ,but everything was circulating fine until I changed out the radiator. Water pump has been changed also.

 

Could it be an air pocket? Are you sure you bled the cooling system?

Just saw that you replaced the thermostat too, dumb question (but I've seen people do dumber things), but are you sure the thermostat is in properly? Like not backwards/ upside down?

 

I have taken the thermostat back out and checked it just to make sure. Yes I have done something that dumb before, but not this time. Air in the system is the only thing I can think of. Im not a good enough mechanic to know whats going on with it.

 

If it is an air pocket, heating it up and then turning it off is a good way to clear it. So you might be fine now, but check the level of coolant before you turn it back on. Sometimes the air pocket will block an area and when it clears the coolant flows down into the blocked area, so you have to top it off.

Check the gasket on your radiator cap. If it's flared it might catch and not open or close. Sometimes, if the cap is bad, the upper radiator hose will collapse when the engine cools down. Radiator caps are cheap. If you replaced the radiator, replace the cap.

 

Did you just pour coolant in it and call it good or did you do anything to "burp" it?

 

I did the warm up with the heater on. After the boiling got so bad and the temp started rising I just shut it down.......thanks for all the input so far everyone!

 

Besides all the circulation issues, does anyone know which sensor that is in the pic I posted above. It goes in the water outlet from the block to the upper rad hose. I cant find anything online about that part.

 

I'm not a Toyota expert but I would assume its your coolant temp sensor.