Can't figure out a coolant issue

Hey guys and gals, so I replaced my water pump (2.7 3RZ) not to long ago and I'm having trouble with what I think to be air in the system. Refilling the system, I let it get to temp with the cap off and filled the rad as needed. Had pretty good heat in the vents at the time and the needle stayed in the middle of the temp range.
My problem is that my lower rad hose stays cold no matter how long I let it idle or drive, and I only have luke warm heat in the cab. I have pulled the coolant hoses on the heater valve to try and bleed air, as well as idle with rad cap off and squeeze all hoses with an incline in the front end.

I'm thinking the thermostat could be a problem but the truck doesn't run hot. Also the fact I only have slightly warm air makes me think air is somehow trapped in the system, or the heater core isn't getting enough flow?

If anyone has any tips or ideas I'd love to hear them, the truck runs great but this has been bugging me for a while, and I could use some decent heat. Thanks

 

I suspect the thermostat is also (stuck open). The bottom hose should be cool and the top hose hot. The water flows down in the radiator. You could do what semi trucks do......cover a portion of the radiator to get the engine a little warmer.

 

I guess it could be stuck open, but it seemed it was doing the same thing in the fall at 10-20*C. Right now at below zero temps the rad hose stays ambient temp, not even moderately warm. My top hose gets hot and the temp needle is where it always sits. Ill likely pull the thermostat when I get a chance and see what happens

 

See if there's a small hole in the edge of the thermostat. It helps dissipate any air in the system as coolant is added. Some thermostats come with a hole in them or drill your own. (1/8th inch is fine) check to see if the overflow tank hoses have an airtight seal so when the motor cools coolant can be sucked back into radiator.

 

Yes, it should have a small hole and the overflow tank should have a hose going to the bottom of the tank. That way when the anti goes back in the rad, it does pull air in.

 

So I replaced my T-stat and still having the same problem. Lower hose is cold to the touch after any amount of driving. It's around -5 or -10 degrees celsius but it should be getting hot enough to open no?.
Jiggle valve was roughly 12 O'clock on install and I burped the system. I did noticed my rad fan seemed to run all the time which I found interesting, but it spins freely with engine off. Not really sure where to go next with this.. I may put a block in front of the rad and see if I can get the engine hot with less air flow.

 

The lower radiator hose should be cold, especially at sub-freezing outside temps. The thermostat can still open to let this cold coolant in because coolant in the block is constantly circulating past it on the opposite side where the wax thermostatic element is.

The bottom line is if your gauge is reading normal and a scan gauge hooked to the OBD-II port shows your engine is reading 180+F then the thermostat is working correctly.

If you are not getting hot air inside from the heater core then that's a separate issue with the heater core, heater core hoses, coolant valve on firewall or blend door under dash. Do you set it to recirculate?

On the 2001 is the radiator fan hooked to the engine pulley? If so it should always spin while the engine is on. Having too much air going through the radiator should never matter anyway because a good working thermostat should still keep the engine at proper temp.

 

After you get the temp gauge up to normal, grab the upper radiator hose. Now you know what it feels like, good and hot, grab the hose coming from the heater core that goes to the control valve on the firewall. Then grab the hose that goes from the control valve down to the engine block, which is just on the other side of the valve. Now grab the other hose that comes out of the heater core. Do all the hoses feel really close to being the same temp??? If they are all hot, then you have fluid going threw them. Make sure the heater knob is turn all the way up and the fan is running on high in the cab. If so, and you have cold air coming from the vents, then the problem is under the dash.

 

Cant quite tell by your wording but you do know the lower hose will stay much cooler than the top right? The tstat wont open and flow hot or warm water.through that hose. It will open and take cold water from that bottom hose to send into the engine to then be expelled out tje top hose back to the radiator to cool and work its way back to the bottom of the radiator. Another fella mentioned this earlier aswell so forgive me if you have a full understanding of your system and whatnot! Just kinda seemed from your wording that you expect the lower hose to be hot like the tstat opens and flows water out the block into the bottom of the radiator.


BTW wamego and Drz put it well as far as what to look for to determine if your issue resides under the dash there inside the cabin... IDK, its strange you havent tracked it down...it does seem like a tstat problem but unless its faulty or in backwards surly its working properly...i reall doubt its air, could be but ive absolutely never had a problem with either of my trucks and honestly ive hardly even ever tried to get the air out. The system does.a.pretty good job of it on its own just by running the motor with the heat on. Only thing left would be a super low flow heater core or that blend door thing under the dash in the cabin...

Oh also that firewall valve. I saw you said you checked the hoses to and from that valve and id assume you gave it a once over at that point but you didnt mention it specifically..

 

What does your temperature gauge say on your dash after your truck runs for 15-20 mins?

 

He says it sets at the normal operating temp spot.

 

I wouldn't worry about it, its cold as shit in ontario.

 

Lol wouldnt worry about it having no heat in a cold climate. Yeah staying warm is totally overrated!

 

It's at normal temp

 

Thanks for the replies guys, after doing some more research and reading a couple replies here it seems like my lower hose temp is normal. Being an inlet hose makes sense as to why that coolant will cool down in the there, and these winter temps just make it feel unusually cold I guess. Anyway bleeding the system after install got all the air out and I have pretty decent heat in the cab.
Truck runs well so ill just keep rolling with it.

 

Ahh so it was air then?