Why is my engine overheating?

Hello,

This sounds like your vehicle's thermostat may have stuck shut. Every vehicle has a thermostat in it that allows the coolant to heat up and then it opens at a predetermined temperature to let the coolant flow through the radiator, which cools it. Then the thermostat closes again and the whole process starts over. This allows the coolant to get hot enough so your vehicle has a heater and a defroster. When a thermostat fails it either sticks open or sticks closed depending on how it was when it failed, usually closed. Thermostats are very easy to change and can be done with usually with just a wrench and a screwdriver. In the diagrams down below I have included the Original Equipment Manufacturer [OEM] part number for your reference, a guide explaining all the possible ways your vehicle could overheat for your reference, and instructions for the removal and installation of your vehicle's thermostat. Please go through these guides and get back to us with what you are able to find out. I hope that this helps.

Thanks,
Alex
2CarPros

Is your radiator fan working correctly? This guide can help us fix it

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Please run down this guide and report back.

With the cold air coming from vents, did you purge the air from the cooling system after the thermostat change? Also, did the truck gradually begin to run hotter, prompting the thermostat and pump change? Have you checked for leaking head gasket? This will cause these symptoms. Doc

Hi John R Siders,

Situation don't look good. Symptoms similar to a head gasket problem.

If coolant level is low, it can cause the problem described.
So does a clogged radiator, faulty thermostat.

When engine is cold, is the coolant level in the radiator high or low?
Do you need to top up coolant regularly?
Check the radiator seals for wear and cracks.

Is the vehicle overheating. Or could the coolant temperature sender be faulty?

Coolant Temperature Sending Unit

Ranger
2.3L. On left rear of engine, above oil pressure switch.
3.0L. On top right of engine, near thermostat housing.
4.0L. On top left front of engine

Upper hose is hot. Lower is cool?

Suspect faulty thermostat, bad water pump, restricted radiator, trying having it rodded out. Or take it off and apply radiator flush to it and keep running it through.

Hi,

I read through you description of what is happening. I have a couple ideas that could be causing this. First, you mentioned that within 2 minutes, the vehicle reaches the 3/4 point. That is hard to believe it would happen that quickly. Have you checked the coolant temperature sensor? It may be sending random signals.

The first thing I would check for are diagnostic trouble codes. Here is a link that explains how to retrieve codes on a Ford OBD1 system:

https://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

There is a list of OBD1 codes with definitions at the end of the link.

Next, I would first check the sensor. Here are the directions. Pic 1 below shows the sensor location.

_________________________

1994 Ford Truck Ranger 2WD V6-182 3.0L
DA3 - Check Resistance of Temperature Sensor - Engine Off
Vehicle Powertrain Management Computers and Control Systems Testing and Inspection Pinpoint Tests With EEC IV (OBD I-A System) Pinpoint Tests DA - Intake Air and Engine Coolant Temperature Sensors DA3 - Check Resistance of Temperature Sensor - Engine Off
DA3 - CHECK RESISTANCE OF TEMPERATURE SENSOR - ENGINE OFF
- Key "OFF".

- Disconnect suspect temperature sensor.

- Measure resistance between sensor signal circuit and SIG RTN circuit at the temperature sensor. Refer to the corresponding chart for resistance specifications.

- Is resistance within specifications?

Yes -- For Engine Coolant Temperature (ECT) sensor with a No Start: Do not service Diagnostic Trouble Code (DTC) 116 at this time.

Go to pinpoint test step AA1. See: Computers and Control Systems > Pinpoint Tests > AA1 - Identify Type of No Start

No -- Replace suspect sensor. Reconnect vehicle harness. Rerun quick test. See: Computers and Control Systems > Reading and Clearing Diagnostic Trouble Codes > Quick Test Appendix (Detailed Testing Instructions)

__________________________________

If the sensor checks good and there are no codes, my next concern is the idea that coolant shoots from the radiator after about 45 seconds. That quickly leads me to believe it could be the result of pressure from the combustion chamber via a head gasket. Do a couple checks on this idea. Here is a link that explains how to check for a head gasket issue:

https://www.2carpros.com/articles/head-gasket-blown-test

Let me know what you find or if you have other questions. Also, keep in mind that the reason I'm suspecting one of the two things above is simply because it happens at highway speeds and you have already done all the basics.

Take care,
Joe

Hi and thanks for using 2CarPros.

Can you tell me if the coolant level is dropping? As you are most likely aware, there are different things which can cause the engine to overheat. Things such as low coolant, a stuck thermostat, even a bad head gasket.

With that in mind, I am going to provide a few different links which are designed to help identify different causes of overheating and how to check.

First, if the coolant is low, check the following:

https://www.2carpros.com/articles/radiator-pressure-test

https://www.2carpros.com/articles/car-is-leaking-coolant

https://www.2carpros.com/articles/coolant-leak-symptoms

____________________

Here is a link that shows how to check a cylinder head gasket for leaks:

https://www.2carpros.com/articles/head-gasket-blown-test

___________________

If the coolant isn't low and you can find no evidence of leaks, my next suspect is a bad or stuck thermostat. The first link discusses a thermostat, it's general location, and how to check one.

https://www.2carpros.com/articles/how-an-engine-thermostat-works

Here is a link that shows in general how one is replaced:

https://www.2carpros.com/articles/replace-thermostat

Once you review the aforementioned links, let me know what you find so I can further help.

Take care,
Joe

Been 3 years?

Things go bad

Even new stuff can be bad

Hoses s. Ucking flat?

Could be a head or head gasket issue. Sorta the last test to try.

Got a shroud around your fan?

Test your fan clutch (popular auto parts guys my check it for FREE!)

Are you mixing your coolant externally, then installing it, thus insuring it's the proper mix, throughout (topping off the same way, later on?). Or are you one of those "guessers" just pouring it in then filling with water till you hit the top?

Lesser of the Evils after the clutch test, would be the thermostat. Simple, EZ to do, less than $10

The Medic

Roger, on all of that!

It's really been hot out!

My Jeeps don't over heat, but they are running hotter

Is yours "Hotter" or really pegging the gauge out?

At night, when cooler, how does it perform?

Could be the sender to the gauge, might be inaccurate.

Head Gasket test.A pressure test can be done.A chemical too!

Radiator Cap? It can be tested, or inexpensively replaced

Just trying to help you.I see something new (sometimes hilarious!) Everyday

Are you at the mercy of the wolves?

I may can help there too. If you are willing to broaden your horizons

I'm a Plumber. Learned a lot, bought tools, did not "drink away", my tight limited fundage! Jeeps are my primary transportation, and have been since '81. My hobby too, Mine do not go to a shop, 'cept for alignments. Had 7, still have 6 and 7.6 almost scratch built, 7 From nothingness!

I do it all myself.I find resources, and use 'em to my fullest extent, whether it be my Jeeps, Wife's Escape, Family or friends rigs.I'm called "McGyver" quite a bit.I sub out nothing, at my house. Not even the toaster!

My sole goal here is to help. Especially the CJ guys!

Your Turn

The Medic