Hello! I'm Rixster...
I'd ask you to check some things for me if you would it can benefit our Diagnosis...
Were there any leaks you found?
Have you checked the oil? Do!
Let me know what you find...
Yes it will get to operating temp. but your fans should not run at all times.
It sounds to me like there is a sensor problem. Did you replace the cooling fan switch or the coolant temp sensor?
The Coolant temp sensor is a two prong sensor with a yellow and a black wire going to it. The PCM gets a signal from the coolant temp sensor which when interpreted ques the cooling fans. There really is no specific Fan Switch.
Also This system is a real pain to purge all the air out of. If you have any bubbles in the system it can send you on some real good wild goose chases. Be sure the system is burped properly. It is possible to aquire a defective Coolant Temp. Sensor. I've had a few in my time. Buy the best quality one you can find if not an OEM part. This assures a good clean reading for the PCM.
If you need further assistance I'm here.
The Coolant temp sensor for this vehicle only has two prongs and has a two wire connector that has a yellow and a black wire going to it.
I don't know what you think is the Coolant temp sensor but unless this is something new I don't think you changed the right one. I may be wrong but all my diagrams show two wires...
Yes it is possible to have a faulty sensor so If at all possible I'd go ahead and try another one in there to see what's up.
Well I'm here to argue with you sir. I'm trying to help!
I Know What a 3.1 V6 is! I'm just telling you what I have in front of me.
The Diagram I sent you is for a 1996 Oldmobile Cutlass Supreme with a 3.1 V6.
If your vehicle has a Mass Airflow Sensor then I'm looking at the wrong one. Can you give me the 8th V.I.N. digit and I'll try to find the correct diagram for you.
As for helping you so far... I HAVE answered your question as to what can cause this...
If it worked before and all you did was change t-stat and the Coolant Temp. Sensor
then it didn't work as you'd expect, You have got to have a faulty sensor! If you have 35 Years as a tech then you must know... What else could it be?
If you get me the 8th digit I can get you a diagram.
I found this diagram for a late 96-97 model...
If you look at the coolant temp sensor it still has the yellow and the black wires but has a dark green wire for a cluster feed.
I'm trying to help!
I'm having a bit of a time finding an ECM Relay Diagram but I will keep looking. Meantime here is this one...
I hope it helps!
That'll be cool!
If I've helped at all feel free to click ACCEPT!
You can say what you will. My diagrams came from alldata. They were from the page pulled up under this year make and model you gave me.
If you are 35 year ASE Certified you should know how these data bases are generalized sometimes.
I apologize for not having a library of OEM service manuals at your disposal!