02 Explorer low coolant temp and random stalling | Ford Explorer Forums - Serious Explorations

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02 Explorer low coolant temp and random stalling

redoxy

Member
Joined
March 11, 2011
Messages
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City, State
Edmonton, Alberta
Year, Model & Trim Level
2002 Eddie Bauer
My coolant temperature is much lower than usual. it goes to a max of about 1/4th of the gauge (see attached picture. The picture was taken after driving for more than an hour). The outside temperature is pretty cold lately but my other car gets to normal coolant temp without issue so I don't think that is the problem. Does anyone know what could be happening? Also the car stalls randomly once in a while usually after stopping or when backing out of a parking lot. I have cleaned the IAC valve and throttle body and that did not solve it.
Can anyone help me out with what could be wrong?
The car drives ok otherwise.
Oh before i forget, the battery is less than a year old and the terminals have all been properly cleaned.
Thanks for any help.
WP_20121224_003.jpg
 



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Ive never seen my temp guage higher than that, even with a brand new 195deg thermostat. Im not saying its normal, but it could be for all i know. I checked the datastream with a scanner and it showed 200 while idling after a long drive, so i know the temp is right where it should be
 






My older Explorer did this a few years ago. The other symptom I had was very limited heat in the cab as well. Replaced thermostat and problem was solved. If you are getting hot heat in the cab it could be the temperature sender unit that tells the gauge what the temp is. The coolant temp sensors are not expensive and are relatively easy to replace.
 






Thanks everyone for the input.
I am sure the gauge reading is not normal as it was somewhere in the middle before and also the user manual says at operating temperature the coolant gauge should be somewhere in the middle. With the cabin temp I noticed it takes longer to heat up and the cabin doesn't get as hot as it used to.

I will try changing the thermostat to see if that helps
 






Be sure to let us know. The big thing about diagnosing the guage is that there are 2 sensors, and the one for the guage is notorious for not being accurate because it grounds through the threads, any corrosion will cause the guage to read low
 






Replace the coolant temp. sensor in the thermostat housing with a Ford part only. Mine did this very thing recently and got worse as far as the stalling part went until I replaced the sensor. Problem solved.
 






Replace the coolant temp. sensor in the thermostat housing with a Ford part only. Mine did this very thing recently and got worse as far as the stalling part went until I replaced the sensor. Problem solved.

I will replace the sensors while changing the the thermostat. Since today is 24th all the dealerships are closed for Christmas. So I cannot get Ford parts until after Thursday and I'm away from 26th till 30th so that means i will not be able to fix it until after next week.

I will be sure to keep the thread updated with what happens when i finally get to fix it.

Thanks all
 






Thanks everyone for the input.
I am sure the gauge reading is not normal as it was somewhere in the middle before and also the user manual says at operating temperature the coolant gauge should be somewhere in the middle. With the cabin temp I noticed it takes longer to heat up and the cabin doesn't get as hot as it used to.

I will try changing the thermostat to see if that helps

Since you mentioned that the cabin temp is cooler than before, check the "heater core valve" to see if it is working properly. One that is faulty can cause loss of heat to the cabin. It is located running along the passenger side valve cover, connected to the heater core lines that run thru the firewall. A partially plugged up heater core can cause a cabin heat loss problem as well. I ruled out a low coolant level problem since your temp gauge is reading lower than normal for you and a low coolant level would result in a higher temp gauge reading or overheating condition. BTW, my temp gauge only gets approx 1/8" of a inch higher than yours in your pic at operating temp and I get great heat into the cabin.
 






ECT sensor & sender

There are two sensors associated with the engine temperature. The Engine Coolant Temperature (ECT) sensor provides the PCM with the coolant temperature so it can adjust the air/fuel ratio accordingly. The ECT sender drives the temperature gauge in the instrument cluster. It has absolutely no effect on how the engine functions. If your temperature gauge reads low, your heater output is low, your coolant contains adequate anti-freeze, and the level is full, then I suspect your thermostat needs replacement. Some "failsafe" thermostats stay open indefinitely after the engine overheats.
 






You do not state anywhere what engine you have. Mine is also a 2002 Explorer with the 4.0 V6. When I replace my thermostat and the upper and lower thermostat housings I also replaced the coolant temp sensor mounted in the housing because the old one was loose fitting. I did not use a Ford sensor but instead just bought one at Auto Zone. A year later my temp. gauge started to act stupid and spike hot to cold and not move sometimes at all, then jump suddenly. My engine would stall randomly but restart right away and have no issues from then on. My friend, who is a very good Ford trained tech, ran a diagnostic scan and found that at some point the computer thought the engine spiked to nearly 420 degrees. I changed out the temp. sensor with a OEM Ford one and low and behold the CEL went out and I have not had an issue since.
 






You do not state anywhere what engine you have. Mine is also a 2002 Explorer with the 4.0 V6

I have the 4.6 V8 engine.
I just called a dealer and he said the 4.6 doesn't show a coolant temp. sensor and that it uses a block temp. sensor instead. But when I checked rockauto they do show sensors (2 of them both not Motorcraft parts). Which information is correct? can someone confirm for me whether the 2002 4.6 V8 has the coolant temp sensors or not before I buy them?

Thanks in advance
 













Thanks for the link. Unfortunately I couldn't find information on any temperature sensors on the website. hopefully someone else has information on whether the 4.6 V8 engine has coolant temperature sensors located in the thermostat housing like the V6. If not I guess i have to take the thermostat housing apart to find out for myself.
 






Since yours is the 4.6 V8 the issues I had with my 4.0 V6 may not apply to your problem. The one thing I will say is that you should not have to take anything apart to find a temp. sensor in your thermostat housing (if you have one) you should find it mounted externally in the housing with an electrical connector plugged into it. Good luck and keep us posted on your findings/ solution to your problem.
 






From my Haynes manual: The coolant temperature indicator system consists of a warning light or a temperature gauge on the dash and a coolant temperature sending unit mounted on the engine. The Cylinder head Temperature (CHT) sensor (V8 models) or Engine Coolant Temperature (ECT) sensor (V6 models), which is an information sensor for the Power Train Control Module (PCM), and also functions as the coolant temperature sending unit. The CHT sensor (V8) is located in the valley between the cylinder heads (it's actually located on the left head) Remove the alternator- disconnect the electrical connector from the CHT- Unscrew the CHT sensor and remove it. Installation is the reverse for the new CHT. I hope this helps.
 






From my Haynes manual: The coolant temperature indicator system consists of a warning light or a temperature gauge on the dash and a coolant temperature sending unit mounted on the engine. The Cylinder head Temperature (CHT) sensor (V8 models) or Engine Coolant Temperature (ECT) sensor (V6 models), which is an information sensor for the Power Train Control Module (PCM), and also functions as the coolant temperature sending unit. The CHT sensor (V8) is located in the valley between the cylinder heads (it's actually located on the left head) Remove the alternator- disconnect the electrical connector from the CHT- Unscrew the CHT sensor and remove it. Installation is the reverse for the new CHT. I hope this helps.

Thanks JCR for the information. that is definitely helpful. The confirms what the dealer was saying that the V8 doesn't have the coolant temp sensor.
I will replace the CHT sensor and along with the thermostat and see if that helps with the stalling and low coolant temp issues. I will update the thread with what happens
 






hi there, i have a V-8 4.6 2003 explorer also... lil different problem though... my thermostat housing is leaking at a seam where the housing connects to the manifold... i can see lots of residue at the seam. i have to put a bottle of coolant in the last 2 couple of weeks... no other issues so far but i want to fix this... dealer says the housing is welded and unserviceable, that
i must buy an entire manifold... I can feel bolts under the housing... has anyone dealt with this before? can i jb-weld it myself? have the manifold welded by a shop? any ideas thanx fam
 






Just to update with what I did and the results.

So I changed the thermostat and the Cylinder Head Temperature Sensor (used dealership parts). And since I had to drain the coolant I flushed the cooling system whiles at it. I also replaced the serpentine belt since I has to remove the alternator in order to gain access to the CHTS.

The CHTS was difficult to remove and replace since there is virtually no room to use any tool there.

After putting everything back together I took it for a test drive and the temp gauge is now reading more like it used to ( see picture attached) and also the heater is heating properly. I did not experience any stalling wen I took the test drive. But since the stalling was random, i have ti drive it a while to confirm whether it has been fixed or not.

Thank you all for the input.
 

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hi there, i have a V-8 4.6 2003 explorer also... lil different problem though... my thermostat housing is leaking at a seam where the housing connects to the manifold... i can see lots of residue at the seam. i have to put a bottle of coolant in the last 2 couple of weeks... no other issues so far but i want to fix this... dealer says the housing is welded and unserviceable, that
i must buy an entire manifold... I can feel bolts under the housing... has anyone dealt with this before? can i jb-weld it myself? have the manifold welded by a shop? any ideas thanx fam

While replacing the CHTS on mine (also a 4.6 V8) I did notice that the thermostat housing does connect to the intake manifold. But like you rightly noted there are bolts holding them in place but you will not be able to remove them.
For starters I will suggest you remove the intake manifold together with the thermostat housing. Then try detaching the thermostat housing from the intake manifold. If possible then go from there. It could be as simple as placing a self-made gasket between the manifold and the thermostat housing.

I hope this helps.
 



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I had the same issue with my 2002 explorer 4.0 v6...the temp gauge wouldn't go up to normal and my scan gauge read the coolant temp at 166 degrees...I replaced the thermostat with a new ford part and the problem was fixed...my guessing is that the thermostat was stuck open...the temp now reads normal and the scan gauge reads 190 degrees.... hopes this helps out anyone else with this problem
 






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