Replacing Thermostat – Tips/Tricks?

[jlells01]

Since I started driving this car again a month or so ago, the coolant temperature gauge has read very low (about ¼ the way up the gauge). It does produce heat out of the vents, but not as warm as I think it should be, so I’m assuming that I have a thermostat that is stuck open…

 

As I reported in another topic though, the engine runs great, and is getting 26mpg's in mixed service...I just have to keep the fan running at anything less than 70-75mph to keep the cab warm during these winter months...

 

Would you agree?

If so, do you recommend a particular thermostat for this car (’95 3.1L)?

Any tips, tricks, etc?

[chadz34]

I think your seeing really good fuel mileage. As far as replacing the thermostat, you could go with a 160, or 180, if you want it running fairly cool.

[sl3196]

HMmm I thought 1/4 of the way up on the gauge was normal for a 3100. (been a while since I had my cutlass though) I would get a Napa Superstat to replace the one in there if you decide to go that route. (stock 192-195 temp is what I would get too)

 

As for taking the thermo out, I just used wrenches and took the bolts out lol. They are kinda in a hard spot but I didn't have to much trouble. Some have removed the throttle body to get to them but I didn't.

[TeeJay3800]

It can be tricky to replace the stat on a 3100. I would go with a Stant SuperStat and try to get a 180° unit. I ended up having to ask for a F-body 3.1 T-stat since the parts store's computer didn't list a 180° model for a W-body. Once you get to it, its pretty simple to swap out. Just make sure you replace the gasket and bleed the system afterwords.

[jlells01]

As Chad pointed out, I am getting pretty good fuel economy (EPA rating of 21/29), so I'm a bit hesitant to change, but it should probably be done.

 

...Just went out and looked, and my gauge reads from 100°F to 260°F, which would mean it's running at around 140°F.

 

The O.E. t-stat for these cars is a 195°F version, correct? It is common knowledge here that this is too warm for these cars? Is a 180°F version a better idea (as a side note, that would probably "look better", as 180°F is at the 1/2 way mark on the gauge)?

 

Thanks everyone for the replies so far.

[DiscoStudd]

Some people on this board with the 3100 removed their throttle bodies to get to the T-stat housing. I managed to change the one out on my 95 GP without removing the TB.

 

Start by removing the airbox. Remove the bolt that holds the metal heater pipe to the water pump on the passenger side of the engine so you can move the pipe up 1/4" so you can access the top bolt of the T-stat housing. The bottom bolt of the housing can be accessed by reaching around and under the exhaust crossover pipe. The bottom bolt doesn't need to be removed, as the bolt hole is notched for easy removal...

[TeeJay3800]

The O.E. t-stat for these cars is a 195°F version, correct? It is common knowledge here that this is too warm for these cars? Is a 180°F version a better idea (as a side note, that would probably "look better", as 180°F is at the 1/2 way mark on the gauge)?

Using a 180° stat only helps the engine run a little bit cooler, which is always a good thing. 180 is fine for use with the stock computer. I've heard running a 160 will cause the motor to run rich.

[sl3196]

With a stock car I would just run a 195*. 180 can hurt the mpg a bit and heater may not be as warm.

[jlells01]

Thanks guys.

 

Do I need to add any sealing product to the cooling system after I change the thermostat out?

 

I do believe the 3.1L (as well as the 3.4L) is notorious for cooling system leaks...

[sl3196]

Nope just make sure you use dexcool or totally flush the system if you want to use the green stuff.

[jlells01]

Nope just make sure you use dexcool or totally flush the system if you want to use the green stuff.

 

It already has the "green stuff" in it...

 

Did the '95 come with Dexcool? Thought that started in '96?

[sl3196]

I thought it did... Not sure though, I know my 96 came with dexcool.

 

Just keep using the green then.

[TeeJay3800]

With a stock car I would just run a 195*. 180 can hurt the mpg a bit and heater may not be as warm.

That is a possibility, but did not happen on my car. Mileage did not decrease, and the only thing I noticed with the heater is that it takes a little longer to get good heat. Once the motor reaches 180 though, the heater is just as warm as with a 195 stat.