Here’s a problem that seems to stump EVERYONE.
1996 Ford Thunderbird 3.8 V6
*rebuilt engine
*new radiator
*new water pump
*new thermostat
*new MAF sensor
Driving 35 miles in the morning car never seems to come up to full operating temperature, staying on the low side of normal. Driving 35 miles home in the evening car will go from low side of normal to high side of normal during the drive and fluctuates between. What is causing the Temperature gauge fluctuation? A normal car should get up to temp and STAY pretty constant.
*Before the MAF sensor was changed it would get on the hotter side of normal on the freeway going up hills and stay warmer until coming down the hill stemming from a lean mixture P0171 & P0174.
You cars temp fluctuates within the normal range, this is normal, there I fixed it.
You are right my 2005 F150 is rock solid after warm up, I retract and also suggest to bleed system.
I’ve never had a car that is behaving itself properly whose temp fluctuates.
I would first make sure that all of the air has been bled out of the cooling system.
Are you sure the temp sensor is working and the dash indicator is working?