coolant temp surges

[irishpilot]

Hello,

I am wanting to know if it is normal to have the guage move when the thermostat opens?

In all the cars I've owned including other fords, my temp guage stayed within the normal temp and never moved once the engine was warmed up.

If its not normal is there anything I should check for?

 

[Tony H]

Are you sure you are topped off with coolant. That can cause a fluctuation.

My 'X' does move a little more then any other vehicle I've ever owned.

 

[RyanT85]

mine also moves occasionally up and down from time to time but nothing drastic

 

[trucku]

maybe you have a failing thermostat. It could be allowing engine to warm too much then when it finally opens cools down quickly causing needle move. My needle on my 02 never moves although the scanguage shows up to 4 degrees fluctuation at times.

 

[LXNavajo_94]

Mine was doing the same thing recently. I was never sure if it was the thermostat or the temp sending unit I replaced both. All together parts were like in the 10 to 12 dollar range.

 

[mikeinri]

You have to take all the factors into consideration. If it's cold outside, and the truck has been sitting overnight, what you describe is normal. The temperature will rise, the t-stat will open, and the cold coolant will enter the engine. You will see this on the gauge, as a rise, a drop, and a rise as the coolant mixes in the engine and continues to equilibrate.

If it's super cold enough outside, it's possible that the t-stat will close, then re-open once the cold/hot coolant mix in the engine gets to temp. It would then re-open and repeat the sequence above. You will see this as rise, fall, rise, fall, rise, etc. until the engine coolant temperature roughly equilibrates through the entire system.

Mike

 

[trucku]

Thermostats do not just open and close. They progressively open as the temp rises and closes accordingly. Your temp gauge should not move around so much. I get 4 degree drops the most this winter (scanguage), but run regularly at about 197F, but my gauge moment is barely noticeable.

Its either a sending unit issue, thermostat or both.

When did you last change the thermostat, flush the coolant out?

 

[irishpilot]

thanks guys!

I will do a flush and change the Tstat. Where is the sending unit located at?

TIA

 

[trucku]

for my 02 its right on the same housing that the thermostat goes in. Buy yourself a manual, it has lots of great maintenance information and shows where everything is.

Good Luck

 

[Alanslinky]

My temp gauge goes up, then down, then up, then down the entire time my truck is running. I've replaced the thermostat, the temp sending unit, the radiator, and flushed, filled, and burped the coolant. So after that i just have been assuming my gauge is faulty.

 

[trucku]

I suppose you could have a sensitive gauge or something. I just never experienced a temp gauge move up and down with any of my other vehicles and they were pos...lol.

As long as your not overheating, I suppose all is well.

 

[Jason94sport]

You have to take all the factors into consideration. If it's cold outside, and the truck has been sitting overnight, what you describe is normal. The temperature will rise, the t-stat will open, and the cold coolant will enter the engine. You will see this on the gauge, as a rise, a drop, and a rise as the coolant mixes in the engine and continues to equilibrate.

My 94 does this. My coolant system is 100% working fine. My other 94 did it as well.

On a 1gen X this behavior is almost always normal.