Changed radiator fluid, return hose remains cold

hello fellow tundra owners. ive owned my 4.0 6cyl 2013 tundra since new. after too many miles (162k) i changed the radiator fluid after flushing with distilled water for 6 gallons. during the change i drained the radiator and replaced it with another gallon of water etc. ran until the temp gauge indicated normal temp. the problem is the return hose is cold? i went to town and back and same thing. unfortunately here in north florida its unusually cold. under 40.
is there a bleeder valve on top of the 4.0 L engine. the information i find online is for 8cyl engines.
thanks

 

For what it might be worth... I replaced the radiator on my 4.7 V8 and same thing, the lower radiator hose only gets lukewarm. I am sure all the air is purged out and the temperature is 188 at the hottest (from my scan tool), so I guess it's right.

I've heard others on here say the same thing about the lower hose only being lukewarm too.

 

thanks, inlet hose hot. cabin air hot. return cold. ugh.

 

Welcome from LA (Lower Alabama)!

 

Welcome from NY.

 

thank you. glad to be here.

 

That in my opinion sounds like the thermostat is stuck open. Is it the original thermostat?

 

yes. but the temp gauge is working fine. starts at cold and goes to almost halfway to hot. if it was stuck open why is the inlet hose hot but the outlet hose cold. ive sqeezed the hoses and they both seem to have fluid in them. its been cold (28 deg this morning), so its hard to say whats going on. im going to purchase a heat gun this morning.
its possible that its working fine but id rather not blow the engine just because i "think" its working.
another question is where is the sensor located? if its in the block then the temperature of the block is ok.
is there a bleeder valve at the top of the engine that i can open and run the engine till coolant bleeds out of it?

 

So the cabin heater is blowing hot air? Try turning the inside temperature down and shut off the blower. Your heater core is a cooling radiator and with colder ambient temperature it may provide much of the required cooling for the engine.

 

thanks ill try it. the difficulty is trying to verify that the coolant is circulating. i understand that the cabin heat is a set of coils with hot coolant running through them. so maybe your right. if it wasnt circulating through the block would the air blow cold?

 

There is a few ways to figure this out. If you're squeezing the hose, then you may have air in there somewhere still. These trucks have proven difficult to remove all the air out of the system. What I would do is jack up the front chock the rear tires, remove the radiator cap and turn it on with heater and defrost on full blast and heat. All dials cranked over. Check your level of coolant constantly as well as your temp gauge. The V8 of bleeding coolant should be very similar. You may have better luck with a Tacoma video, but same rules apply. Add coolant as necessary to top off the radiator.

If you have luke warm heater there is air in the system. Additionally you can plug in your obd2 reader and check to see if your O2 sensors go into close loop mode. This means that all systems should be working including the thermostat. If it remains in an open condition then you may need to troubleshoot your O2 sensors as well as your thermostat. I hope this helps you some. I can vouch for the thermostat as mine is still the original with almost 300k miles, but there are failure and may need to be addressed.

 

thanks black demon. i saw a tacoma post that said to do exactly that. raised it this morning and ran it. i think the system may be ok. the temp gauge is working fine so i dont think the engine is overheating. also, a video i saw showed the upper radiator inlet hose should get very hot if the t-stat is working (which it does). the lower hose may be cool because the radiator is doing its job. both hoses are tight when the temperature comes up to normal, (just under halfway between C and H.)