Thermostat question

[fourwheelford]

I have a scangauge II that gives me readings on the general goings on of my motor. My question is the other day I was driving and noticed the temp got up to 210 to 213 then dropped down really fast to the 190's I figured it was normal but then checked and the thermostat shout be 195*. The water pump is new but I have never changed the theromstat. Does anyone think this temp is a problem? Is it normal for that kind of fluctuation? At what temp will the tranny get damaged? My coolant is full and is nice and green. Thanks in advance for any info.

 

[wiesket]

does your vehicle have an electric fan for cooling? I am not familiar with the setup for your vehicle, but it almost sounds like the fan kicked in and started to cool things down. Also, does it do this all the time or was this a one shot deal?

 

[fourwheelford]

I dont remember if its normal, I dont think it is. I noticed it and thought it was odd so I doubt it happens all the time. And the truck has a clutch fan not electric.

 

[Rearanger]

Does anyone think this temp is a problem?

Could be sticking thermostat. You'd have to know the open/close temperature design range of the thermostat. The easy test would be to install a new thermostat. You could also test it by immersing it in water that you gradually heat and watching a thermometer to see when the stat opened.

 

[Earl43P]

If you were driving a steady speed when this occurred, I'd replace the thermostat because it stuck.

For an $8 part in a 15 minute job, it's kind of a no-brainer. The Scangage told you the truth.

FWIW, I always drill an additional "bypass" 1/16" hole in new thermostats as a safeguard from sticking. That way coolant can always get by. You'll notice that they have a hole with a loose rivet in most. Same concept. They still regulate temp just fine with my added hole.

 

[Big Jim M]

C'mon guys! The thermostat isn't rocket science! The thing is on the OUTLET of the hot coolant. When it gets to it's opening temp it opens and allows cold coolant to enter the OTHER END of the engine. When this coolant finally reaches the thermostat it closes.. NOW the engine is full of that colder coolant.. In the winter that MIGHT be as listed above. If the gauge is finely degreed it MAY be possible to "see" these changes in engine coolant temperature. HOWEVER the gauge normally on our engine isn't that finely tuned.
When driving on a turnpike at a steady speed that gauge should level itself out and be really close in temperature. Then when in traffic it might go up and down as posted.
Big JIm

 

[JP02XLT]

You can see the temp swings with a Scangauge, Mine does the same thing, It all depends on how fast the thermostat reacts, opens or closes as it should to regulate the temp. I have never seen a T-stat that is not off the opening & closing by 5-8 maybe even 10 degrees from what it is marked. My 195 deg stat will normally go 210-212 then open, & eventually it will level out the engine temp. The gauge on the dash, reads right in the middle whether its 195 or 215.

JP02XLT

 

[fourwheelford]

Thanks everyone I was in town driving and I think I was stopped but I don't remember, I got the scangage for christmas and hardly drive the truck, I figured the Tstat had a certain range of fluctuation to it nothings perfect right