2003 Ranger 2.3 - Truck has no heat after running for 20 min - Replaced Thermostat and checked the original one which opened in hot water, replaced water pump - Lower Radiator Hose is Cold and upper is slightly warm, the small hose that bypasses the thermostat is hot and the hoses that come out of the firewall from the heater core are warm/hot. The temperature gauge is in the middle of Hot and Cold which seems normal. I did notice the temp gauge go to the top level for a very short time and the temp light come on, this lasted only for about 20 seconds and then gauge was back to normal. My next thought is a clogged radiator which I have never had on any vehicle. Does any one have any suggestions?

 

Welcome to the forum

What is the outside temp where you live?

There are many engines/vehicles that simply don't need radiators in the winter months

Radiators are for EXTRA cooling, needed in summer months

If the heater is not blowing hot enough then put a piece of card board in front of 1/2 the radiator to block some air flow into engine bay
Most semi-trucks have covers over the front grills to slow or stop air flow in the winter months


Did this spike in temp, above 1/2 on the gauge, happen within a day or two of installing the thermostat and refilling the system?
If so could have been air trapped in the system, it would be purged by now

2.3l Duratec has a thermostat on the lower rad hose, usually 180deg, this means the lower part of the engine must get above 180deg for it to open and allow coolant to flow into the rad thru the upper hose
Upper engine should be about 190-195deg at that time, other engines have thermostats on upper rad hose, they use 190-195deg thermostats, so lower rad hose temp would be 180 when rad is being used

Most radiators provide 15deg of cooling without the fan on, 20-25deg cooling with fan

1/2 on most Ford temp gauges is 210degF, so norrnal operating temp of 190-195deg would be just below 1/2

 

Live in Wisconsin - outside temp is in 30's - truck was sitting in 40 degree garage for two days after thermostat was replaced while I worked on water pump. I replaced the water pump, then I let it idle for 20 min in garage and checked the fluid level. The top radiator hose was warm and bottom hose to radiator was cold and no heat inside of truck.

The temp gauge holds steady in the middle between cold/hot - it spiked the following day after thermostat was replaced - so I agree that could of been air bubble.

The two hoses for the heater core are both warm/hot - so shouldn't the heat at least be blowing warm instead of completely cold?

Can the heater core be plugged if the heater core hoses are warm/hot - I would think if they are warm then the water is circulating through the core?

I understand the thermostat not opening due to cold weather, seems like being in a 40 degree garage it would get warm enough. Even without the engine getting warm enough to open the thermostat, the coolant for the heater core circulates through the core without the thermostat being open due to the smaller heater hose bypassing the thermostat.

All the air / heat / vent ***** / dampers and controls appearing to be working properly.

Tonight i'll try the cardboard and if that doesn't help I'll then connect a garden hose to heater core hoses and gently flush the core.

Let me know if i'm missing something or my perception on how this cooling system works.

Thanks,
Cary

 

Reverse the heater hoses at the firewall, this should be done every 2 years or so, similar to back flushing the core, reversing the flow thru it

Check fuse #41 in engine fuse box, 20amp, it powers the thermostat heater(and other things) but would expect multiple codes if it was blown

 

Excellent idea on reversing the heater core hoses, i'll try that this evening

 

When you are out driving this will generate more heat in the engine, engine load, if temp gauge starts to climb then you could have limited flow in radiator
You can for test this, after driving, by move fan shroud back and running your hand over radiator fins, should have nice even heat, warmer near upper hose and then getting less warm going toward lower hose, any cold spots are blocked passages/areas

 

Reversed the heater core hoses and ran the truck for 30 min. The heat stayed cold the entire time, the temperature gauge stayed right in the middle and several times would jump up to overheat and temp light would come on for about 15 seconds .... this happened about 5-6 times when speed was around 60mph.
Checked heater core hoses after the test drive - both were hot, hot enough to make me believe water was circulating through the heater core.

Upper radiator hose was warm/hot and the bottom hose was cold, not even warm.

Radiator felt cold to the touch over entire surface.

I didn't check the fuse .... will have to do it tomorrow.

If both hoses are hot, then water most be circulating through the heater core ..... why no heat?

Since lower radiator hose and radiator are both cold, possibly the radiator is clogged.

Tomorrow i'll check if radiator is clogged unless you have better suggestion

 

Everything I'm reading in this thread indicates a partially clogged heater core

Your heater core has about 30 tubes going through it, if 25 or so of those tubes are blocked/plugged/restricted water can only flow through 5 or so.

Those 5 or so open tubes can flow enough water through the core to keep the water hot on the output hose.
Those 5 or so open tubes can pass enough water through them that even hooking a garden hose to one side of it will look like you have full flow.

My bet would be after replacing your heater core, you'll be back asking how to turn down the heat.


Been there, done that.

 

Heater hoses should start getting hot as soon as engine starts, if both are cold after 4-5 minutes then no circulation, and that can cause temp gauge to go up and down randomly
After driving for a bit both heater hose can get hot from heat transfer inside the hoses, that's what coolant does, transfers heat


Yes, put a bucket down under lower rad hose, take rad cap off and upper rad hose, to let air in
Remove lower hose and all coolant should drain from rad within 5 seconds, super fast
If it drains slowly then its clogged

 

Tomorrow i'll check the radiator per your suggestion.
I would think I would get a trickle of heat with at least a few tubes transferring some antifreeze .... guess not

It make sense that if the radiator is clogged then so would be the heater core ...... guess i'll have to watch a couple of youtubes videos on heater core replacement for 2003 Ranger with 2.3

Thanks Again,
Cary

 

I checked the radiator and the heater core, both flow water without any issues. Water drains through both really quickly.
Now I need to get some antifreeze and refill the system.
Any thoughts on it being the Heater Control Valve Solenoid...... I’ve been researching but haven’t found a way to test this valve.

 

The valve in the engine bay on the heater hoses, doesn't control heat per say, its only used in MAX AC to stop flow to heater core, to reduce extra heat in the cab
It should have a vacuum line on it, vacuum line runs to the firewall and to the climate control on the dash
With engine idling and climate control OFF make sure there is no vacuum in that hose
Then turn climate control to MAX AC and there should be vacuum in that hose

If that is correct then the climate control part is OK, valve could still be broken, always bypassing heater core, before refilling the system you can remove the valve and check if valve is working by watching inside the valve while using a short hose on the vacuum port, suck on the hose to apply vacuum to it

 

The valve is doing the opposite of what you mentioned.
While idling and controls are off there is a vacuum. Then with air conditioning fully on there is not a vacuum.
since both heater core lines are hot that tells me the water is circulating correctly through the core and valve.
Could something not be allowing heat damper to open?
Recap - replaced water pump and thermostat, checked flow through radiator and heater core.
What’s left?

 

Unhook the vacuum line and plug the line, so no vacuum leak

See if you start to get heat in the cab

The Default setting for that valve should be HEAT in the cab, like default for vents in the cab is DEFROST vent
Default is No Vacuum available
So it wouldn't make sense, engineering-wise, to have it operate the way you describe since it could be setup either way


The only actual Temp/heat control is the Blend Door in the cab, thats what the temp **** controls, it directs air from the fan either thru the heater core(HOT) or around the heater core(COLD), and has partial settings for cooler or warmer

Google: Ranger Blend Door

 

Filled radiator and plugged the vacuum hose with a nail ...... heat core hoses are and still no heat ..... not even a little.
Pulled glove box and watched the vents open and close between air conditioning and fan switched is turned off.
Have to figure out if proper operation of control is taking place when turning the heat **** back and forth from cold and hot?
I’m out of ideas

 

It is possible to get flow thru the heater core just at the top of core, so lower core is cold and no neat in cab

Blend door motor is a Stepper Motor type, so has pre-set voltages that turn it to a specific degree, 10deg, 20deg, 30deg ect.................so at any position of the **** the actuator motor should be at that corresponding degree

It is possible for Blend Door rod to break, so actuator motor is turning a broken rod end and not moving the Blend door at all

You can pull out the actuator motor, and see if rod is broken, and move the blend door by hand, its hard to remove but only other way is to cut open the box and put hand inside to see if its moving

Google: Ford ranger blend door motor install

Watch a few videos