2004 5.7 Hemi No Heat and Overheating

[Alenz21]

Hey everyone I have a 2004 5.7 Hemi that has no heat at an idle as well as overheats when driving or if let sit idle. Most times when driving down the road you will have heat (engine reved up to 1500+RPM) but then when coming to stop light it will blow cold air again. Also at other times when driving it will be blowing cold air continuously and at that point is when the truck will overheat. I have replaced the water pump, thermostat and radiator(due to leaking) and still nothing has changed. I replaced the heater core roughly 4 months ago and the front main seal shortly before this issue started happening. Performed a Hydrocarbon test and head gaskets checked out to be okay. I have been using a vacuum fill every time to ensure no air in system. Any information would be much appreciated! Thank You

 

[srv1]

possibly a stuck t-stat,"new"does not always mean it works.ck to see if your top rad hose gets hot,this will let you know the t-stat is opening.im thinking though you may have done this already by the other things you did.it can also only be opening only a little.im thinking that or blockage somewhere.did you flush the system?

 

[Alenz21]

SRV1, I have put in 3 different Thermostats and same issue on each one. The top Radiator hose does still get hot. Yes, the system has been flushed.

 

[HemiLonestar]

SRV1, I have put in 3 different Thermostats and same issue on each one. The top Radiator hose does still get hot. Yes, the system has been flushed.

Did that include the heater core and was it checked to see if clogged? People tend to forget the HC is part of the cooling system.

 

[Alenz21]

Yes that did include the heater core

 

[RoadRamblerNJ]

I'm no help.
You already checked everything I was gonna suggest.
Still sounds like air in the system.