HELP! The heater on my Ranger does not work; when I turn it on, it draws down the engine to the point that I have to turn it off immediately. The temperature gauge doesn't work even though I replaced the thermostat (my mechanic checked the thermostat to be sure I installed the correct one and that it wasn't stuck). The codes look like the engine is running rich and my gas mileage is way down. The only sensor that I have replaced was the O2 sensor on the down side of the exhaust manifold, before the catalytic converter (I couldn't get to the other sensors with my limited tools). The question that I have is whether the heater issue may be related to the temperature gauge issue? And, since the engine is running way too cool could the "brain" be adjusting the fuel mixture hence my reduction in gas mileage? And, what could be causing my engine to run too cool and why wouldn't the temperature gauge work? Possibly another sensor or regulator?? Any ideas or comments greatly appreciated!!

Thanks!
Handymam

 

On the '05 the temp gauge on the dash is run by the computer.
The computer uses an ECT(engine coolant temp) sensor to get the temp.
ECT sensors are not expensive so I would just replace it, 3rd party are under $15 usually

Should be located right next to thermostat housing, it is a 2 wire sensor


Yes, if ECT sensor is reporting cold engine the computer needs to run the engine Rich, Choke mode, so MPG would be down.
But computer should also give you a code that tells you that engine is not going into Closed Loop(warming up) after about 5 minute of running.

If you have codes you should post them.
Many people do not understand what codes mean, even some mechanics, they are not to be taken literally.
i.e. Lean code does NOT mean engine is running lean, and Rich code does NOT mean engine is running Rich.
Both mean the computers base calculation for the 14:1 air:fuel ratio(MAF sensor data) are not being confirmed by the upstream O2 sensors feedback(data)

Codes do help point to problems but they should be looked at as a whole, all the codes.
Often clearing the codes and then driving for 2 or 3 days and then re-reading them will further help to get to the heart of the problem.


Stock Thermostat should be 190-195degF, parts guys often give you a 180degF, cooler is not better.
Also run 50/50 coolant/water mix, all coolant will run way too cold

To test thermostat start cold engine, feel the upper rad hose, it will be cold
let engine idle for 2 or 3 minutes, feel upper hose again, it should still be cold, if not then thermostat is open and it shouldn't be
After 5 to 8 minutes thermostat should start to open and upper hose will start to warm up.

The Thermostat is the only minimum temp control on the engine, so engine actually running cold has to be a thermostat issue, engine should run with coolant at 200degF so quite warm to the touch on upper rad hose after full warm up.


Not sure what you mean in this: "when I turn it on, it draws down the engine to the point that I have to turn it off immediately"
You mean the engine starts to stall or the temp gauge goes down more?

 

Thanks for your reply. The temperature does not work at all; on cold all the time. When I turn on the heater, the engine starts to stall.

 

When you turn on the Fan, the engine starts to stall?

Adjusting Heat/Cold couldn't cause engine to stall, unless there as a short in wiring.

get a Volt Meter and set it for DC volts
Test battery voltage
new battery is 12.8 volts
5 year old battery is 12.2 volts

Start engine
Test battery volts again
just after starting battery voltage should be above 14 volts but below 15 volts.
After idling for 5-10 minutes battery voltage should be 13.6 volts
Turn on headlights, voltage should drop then come back up to 13.6 volts
Leave lights on, Turn on Fan to High, voltage should drop then come back up to 13.6 volts.

If this doesn't happen then battery and/or alternator is your problem, and low voltage can also effect computer and engine operation.
So get this fixed first.

Does your Battery light work?
It should come on when key is turned on
Then it should go off when engine is started.
If there is no Battery Light then you have a blown fuse and alternator is not being turned on.

 

Sounds a wiring issue to me too, there might be a shorted wire somewhere.

 

Have you had the heater core checked?