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I have a 1990 with the 2.3 and it is getting too hot. I have flushed the radiator, changed the thermostat and radiator cap. The water pump is working. I think it may be the fan. I direct connected it to the battery and it came on. But it seems to not come on until the gauge is at about 3/4 or more. What controls the fan? A thermostat? A relay? Where is it and how do I check it? Thanks
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Is it over heating at Idle or during driving speeds? Is there any debris and such that is stopping the air flow over your radiator?
If it over heats at Idle, it will probably be your fan (seeing as you said you changed your thermostat).
Over heating at cruising speeds could be a bad waterpump. If your driving and it starts to over heat, put the blower motor on high and full heat. If the temp gauge goes down, then its the water pump. Again, make sure nothing is blocking the air flow over the radiator. Check the fins too.
You also might want to ground out your Temp Gauge to make sure it works.
Well I am at my wits end with this d*** car. It still is overheating. I have replaced the water pump, thermostat, radiator cap, fan sensor, and direct connected the fan to the battery to make sure it works, it did. The fan doesnt seem to like to come on until the needle is up around the "N" on the gauge. So I can only think of two other things it might be...The gauge (how do I check to make sure the gauge is working properly?) or isnt there some sort of module for the fan under the dash? If so what does it look like? And can I check it to make sure it is functioning properly? Am I missing anything?
Does the car over heat at idle?
What temp Thermostat did you use?
Do you loose coolant?
Did you pressure test the cooling system?
Did you pressure test your radiator cap?
How are the fins on the radiator? bent? anything stopping airflow through it?
Did you check the CEL?......
It runs at about qaurter to half on the gauge at idle. When you drive it it goes to three quarters to almost pegged, but fluctuates alot between half and full. Thats why I am wondering if it might be the gauge.
Not sure on the temp on the thermostat, got it at shucks.
Run the car in idle and wait to see if the fans kick on. If they do, you know the control side of that circuit is good.
Places like Autozone will loan a tool so you can pressure test your radiator cap and cooling system to check for leaks and of course, to make sure the cap holds pressure.
CEL stands for Check Engine Light. This is the light that comes on whenevr here is an issue with the vehicle usually. Still, if theers any memory codes, it will not show until you try and retrieve the codes. Again most Autozones can check OBD 1 vehicles and do the KOEO and KOER tests for you.
Here is how to test your gauge. You will need a wiring diagram so you using the right wiring.
1. Turn ignition switch to On or ACC position.
2. Connect a 10 ohm resistor between gauge lead and ground. The centerline of pointer should fall within the band around the H mark.
3. Connect a 73 ohm resistor between gauge lead and ground. The centerline of pointer should fall within the band around the C mark.
4. If gauge tests within calibration, replace sender.
5. If gauge is out of calibration, replace gauge.
Thanks, I'm not sure I have equip to test gauge or sender. Here is something though. I do have the code reader for this car and got this code:21, its something about the sensor signal voltage being out of range? got it under key on engine running test. two more things, the gauge is jumpy and the fan wont come (even though it will come on when directly connected to battery.) on even when the temp reaches max (on the gauge at least) Im begining to wonder about the gauge.
The first order of diagnosis you need to do is obviously a visual inspection of the wiring harness and the ECT sensor itself.
Next, you need to make sure you have power going to the ECT. Most sensors on vehicles use a 5v REF voltage. If you have a Volt meter, you could unplug the harness and probe both terminals and check for voltage that way.
You can also try to ohm out your ECT sensor itself. One trick some people do is to take the ECT sensor out, heat it up while its attached to a ohm meter (you can use hot water ect) and see if the resistance decreases. Most ECT sensors are NTC thermistors so, as the temp goes up, the resistance goes down.
If the ECU is receiving the full 5v reference, that means it thinks the engine is running very hot. And that is due to a bad ECT sensor.
The ECT sensor is about $10 at any parts store.
Now for your Cooling Fan, on my 93, the relay is apart of the IRCM. If you have a standalone relay, you can test it with an ohm meter. Also, if you can find a wiring diagram for your year, you can use a fused jumper wire and jump the circuit to see if the radiator cooling fan will kick on.
Well I replaced the sensor...no go still overheats, and fan wont come on. Relay? Heres a dumb question...What about a fuse? Does the electric fan have one and if so where is it?
Worst case scenario, you can hook the fans up to a toggle switch.
However, im not sure if the 1990 Mustang came with the IRCM or not. If you can find a wiring diagram, you could use a fused jumper wire and jumper the control side of the fan and see if it works, if so, the relay is bad. You can also use a test light to check for feed and ground too, thats IF you do not have the IRCM.
The IRCM (Intergrated Relay Control Module) houses the A/C, Fuel and Radiator Fan Relays, that are supposed to be non serviceable.
You might even want to check your fuseable links also.
Again, a wiring diagram, test light and volt meter will work wonders for you.
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'90 overheating
