very little heat front/rear

[braddaddy]

I had different shops look into this back in spring.... They flushed radiator (2x), replaced thermostat (2x),...checked core hoses...said everything was good and had heat on and it was nice and warm...I told them it wont be once temps drop into the 30's... --I had the time and funds to have them look it over so it would be ready for winter.
Well its cold out and the heat is the same....very little at both the front and rear.

 

[Bowesmobile]

Its either the blend doors or its the heater cores. This has been gone over many times here. I have to flush my cooling system again because a vane from the water pump disintegrated and clogged my heater cores. When you flush them, use either white vinegar or buy a heater core flush from a parts store. Then hose them out really well. Both in normal water flow and reverse of flow. If that doesn't work make sure the heater core lines are not blocked at the connection to the engine. If that doesn't work, then replace the heater cores with new ones.

 

[braddaddy]

So how does one verify whether or not its the blend doors?

I thought it was not the core because it happened at the same time and the level of heat front and rear is the same.... but dont the front and rear each have their own core??

 

[Bowesmobile]

Front and rear have their own cores. They are fed from the same plumbing. If you pop your hood and look on the passengers side. There's a rubber hose "T" that comes from the engine and feed the heater core for the front on the firewall. Then two lines go to the bottom of the engine compartment and run to the rear heater core, under the vehicle. The disconnect is a white nylon clip inside of a black circular housing. You have to depress both side of the clip to release it from the male connector. The you can take a garden hose and use the pressure to flush the system out. Just be sure to add some antifreeze to the de-gas bottle on the drivers side when you're done. That will mix with the water you used to flush the system and make sure nothing freezes or boils.

To verify the blend doors are working you can try and take apart the dash around where the doors are located. Then watch them operate. Or you can actuate them and feel colder air and warmer air. They are not easy to get to.

 

[jbanks]

Am I mistaken or, are there some check valves somewhere in the system under the hood? Maybe one of them is stuck? or gunked up?

 

[braddaddy]

Ill be checking the cores this week....

My "T" in the lines do not have the type of quick connect the manual shows. My "T" has black plastic between the hoses.

Not sure if they remove the same...I tried pinching and there really wasnt anything to pinch.

 

[braddaddy]

IDK.... The more I think about it the more things do and yet don't make sense...

1- I cant believe its the blend doors... because both front and rear heat is the same...luke warm. I cant believe both blend doors are bad at the same time and resulting in the same temp--luke warm...I would think one (front or rear heat) would be different from the other.

2- The core issue makes sense... but it looks like both cores are fed separately....coolant doesn't run into the front core THEN into the rear core. It looks like the coolant lines "T" before the front core....so coolant runs separately in and out of the 2 cores....parallel...not in series....right?

3- My temp gauge inside the truck sits right in the middle where it should be...but my hoses are lukewarm / hot ....but i can hold them all day after driving for over an hour....not hot as in "ok these are hot I better let go now"...more like "ok these hoses are nice and warm".

4- There is no pressure build-up...I can squeeze the upper hose with little resistance...when I let go I can hear/feel little bit of surge. Like my t-stat is always open--not allowing pressure to build-up. I have replaced the t-stat 3 times. once myself and 2x at 2 different shops.

5- Thought maybe water pump impellers were worn off....but wouldnt I overheat? Took a 5200 mile trip 2 years ago from Illinois across country to Utah down into AZ/NM/TX and back to Il....In July (still had same low heat issue then) and never had any over heating issues.

I had the Expy in pepboys and they said they flushed the cores...I didnt see it...so I cant be sure...of course it was warm out and they said heat was fine...which it is until temps drop. The colder it is, the less heat...not cold then hot while driving which would be low coolant.

Ill try flushing the cores but I think Im chasing the wrong rabbit.

 

[braddaddy]

I just went out after the truck had been running for an hour and opened the coolant cap...it fizzed like opening a 2liter bottle of pop and that was it.... upper hose was then way easy to pinch closed so I am getting pressure but not the pressure I would think I need.

I should have 16lbs pressure at that cap....I know I dont....

I think I will try to install a gauge in the upper hose to see what kinda pressure I am building up. Maybe using a tee in the upper hose and a gauge in the middle. I still have the old cap....I might tap the top and put the gauge there.

 

[JOEY5.4]

my 98 navigator does a similar thing i notice thought it only happens when my heater control is on automatic so i belive that the blend door from hot to cold is the colprate in my case bolth of my front and rear temps are the same also but only get lukle warm on automatic if i leave it on heat and vent after a startup or two it tends to make heat like a pizza oven.

 

[JUST4FUN]

what brand T STAT are you using? if its stant replace with motorcraft