I'm driving a 2.5L the past few days and noticing that the temp gauge never really warms up, it gets close but then run really cool.

you guys with the 2.5L does the gauge stay in the middle ? or is it normally run low?


I'm thinking the thermostat is stuck open which is why i dont get much heat and why the mpg is so poor.

its a 99 with only 45k miles on it.

 

Mine runs right in the middle!

 

its been below freezing around here and with my larger radiator i can see exactly where the t-stat opens and it is just a little bit before the N in normal... but thats on the 94 gauge.

 

with my 3.0 i usually run at 210*... lately ive been at 200 because of the cold im guessing....


and does my fan always being on mean my thermostat is stuck open?

 

Your thermostat is stuck open. The gauge reading below normal is a symptom of this. Here are a few pics I took to help you replace it.

You'll need:

• Gasket sealer and new t-stat
• a pair of adjustable pliars
• 8mm socket
• 6-inch or longer socket extension
• and a socket wrench.

As you can see in the pictures below, the thermostat is housed in a black plastic water neck that bolts to the face of the cylinder head.

You can see the round opening of this neck in this image. The upper radiator hose attaches to this with a spring-lock clamp. Release tension with the pliars and move the clamp "up" the hose so you can pull the hose off the water neck.
BE PREPARED!!!

• Coolant will spill out of this portion of the hose. Be prepared with a proper catch pan or other device to capture at least a cup of coolant.
• Make sure the engine is COOL and the pressure on the radiator has been released by removing the cap after the engine has cooled.

Here you can see only ONE of the 2 (TWO) bolts that attach the t-stat housing/water neck to the head. You may have to remove the bracket that supports the A/C line that runs in front of the engine (visible in this image) to access the other bolt on the opposite side.


The thermostat has a clip which locks it into the plastic housing. You probably won't need any gasket sealer since you're thermostat housing is sealed with a rubber o-ring. However, a thin layer of gasket sealer is good measure while you have it apart to ensure no leakage occurs.

Reconnect the radiator hose after replacing the two bolts that hold the housing on.

Take the truck for a test drive, then check for leaks!

Your gauge should return to a middle reading and stay constant.

 

thanks man!

 

zabeard, what kinda gas mileage is it getting? This where my temp gauge usually rides. Eventually it will go just a little higher before droping back down to around there.

 

That seems a little low but as long as you're still getting heat I guess it's ok. My 4.0 wastes no time getting right to the middle of the temp gauge and stays there. Doesn't matter if it's 95 degrees outside with the A/C on or if it's 2 degrees like it's been here for the past week during the morning it always stays in the exact same spot and it has a huge radiator.

 

It spends alot of its time where it is in the pic, or slightly lower.

 

the 4-cyl and the 4.0L are VERY different engines and use different sensors and cooling systems and really cant be compared...

 

yep that is where mine is! im getting about 16mpg without estimating my tire size difference.

99 2wd come stock with 26s? ive got 30s on it now...

 

Where are the pics, I wanna see gramps truck.

 

i might take some tomorrow but idk if i will be able to get it out the garage! calling for 12-16 inches of snow by tomorrow night!

 

Where does the needle sit when the engine is cold? (sits overnight)

 

Bear mine is like that on my 2.3L it just gets bearly above the normal line and sits there only time it gets warm is when on the freeway, replaced my thermostat twice and that diidnt change anything just FYI

 

yepper thats where mine sits unless i take a trip to like your house Zach or Marks, then it goes up into the middle.

I have a theory that the dash gauge is more set for the temps of the V6's then the 4cyl and that is why. its just a theory idk if its true lol

 

actually, when im going down the road and look at it, its just barely above the C. It gives off enough heat so that the cab stays nice and warm, and I get around 21mpg, so I guess its running normal. I thought about taking the needle off and reposition it about midway, so that when it was cold, it would sit on the C, instead of like 3 needle widths below it, and would read midway when warm. The only time I see it get any higher is if it sits and idles a while after it has been driven awhile.