Thread: Simple Thermostat Question

So earlier this year, i did my lower intake gaskets with a new upper intake. Mostly flushed the system and put new coolant in. My 195 degree thermostat was replaced around January 2014 due to the old one only ever getting to 170 degrees. My car ran at 190 this summer. I do have a hole drilled it in so i hear that is normal. It ran at 190 on torque, and just below the first quarter mark on the gauge, up until a week ago.

My issue is that now its running closer to the middle/bottom of the gauge and torque is only should around 179 degrees. And thats when it was 15 degrees out and even yesterday when it was 50 out. With my 3800 series 2 in my 1996, it would warm up closer to the 1/2 line and then suddenly drop, which is from the thermostat opening.. This car doesnt do that.. Never have. I do get heat in a reasonable time frame though.

Its being argued in my house that because its colder out, the car will run colder.

Please set this straight and why lol. And is the thermostat already defective?

Thanks

The car will run cooler if you have a hole drilled in it, It's almost like running a 180º in the winter.

I'd install a new stock thermostat if you want it back around 190-195.

And the factory gauge is not very accurate. The first big line is normally around 190-195.

Yeah i knew the gauge was off. Would that 15 degrees help alot with fuel mileage?

Wait. You're saying because there is a bleeder hole drilled in a 195* thermostat, that it will run 15* cooler like a 180* thermostat?
i call BS unless that hole is a 1/4" in diameter.
Most vehicles come with bleeder holes already in the thermostat...

The cars base tune, (if it hasn't been changed) causes the car to run the fuel mix a little rich until it hits ~190, running the coller tstat the engine stays in that mode so yes, it would help if your not tuned to run colder.

I know i put a pretty small hole in it. The one i bought did not have a hole in it. The car is on a base tune. Im currently getting about 18 mpg calculated and im not really driving city at all. During the summer im only getting 21 mpg but it runs at 190*. Itll warm up to 190* degree. Rarely do i ever see it go over that in the torque logs.

Is there any other reason why my car would run cooler except from the thermostat? But i think i mightve been getting this gas mileage before I even changed the thermostat.

its like cold out, cars gonna run cooler now. mines not been past 170 the last few days. its been 20 or colder outside. i got a 195 t stat with fans tuned to 180 that were not on.

Lol dude. You're in buffalo - same town as me. It's been like 20* outside. How long are you driving the car ? I can scoot to home to work before it fully warms up.

Originally Posted by 04lss

The cars base tune, (if it hasn't been changed) causes the car to run the fuel mix a little rich until it hits ~190, running the coller tstat the engine stays in that mode so yes, it would help if your not tuned to run colder.

Open and closed loop functions are set way lower than 190º.

The car should enter closed loop functions at between 50-80º coolant temp but with a delay of a given amount of seconds.

Figure if you start the car at 130º, it will be a OL afr of 13.8-14 give or take, then after 10-30 second delay it enters closed loop functions on whatever the stoich value is.

So it can't be stuck in a "mode", it can just use more fuel because the motor is cooler. A warmer motor is always going to be better at burning fuel. Though the difference is small when we are talking 180-190º. I just prefer 190-200º because it makes no difference in the power department when people say that a lower t-stat is better/needed on these cars.

so now you want to block off 1/2 the rad with card board lol

**** it, i dont care anymore. Im just going to drive it the way it is lol. Gas is only $2 a gallon anyway now

You need anything let me know

winter gas also makes your mpg drop.

cardboards not a joke either. it will help raise your temps. id block the driver side as the trans cooler is on the pass side of the rad. you dont need the tranny heating up.

ive ran cardboard over quite a few rads over the years. first run might take some adding or removing of some cardboard. but after the first trip you'll know if your set up right temp wise.

My other 3.8 didnt do this and this car didnt do it till this winter. It was 0* out for a good week last winter and it never did this lol. Its gotta be because of the air hole that was drilled in it.

ScottyDoggs, Do you use zip ties to hold the cardboard on? I may give it a shot.

you cut the cardboard to fit in the lip and under the lip at the top, it stays there all by its self.

you may have to take some plastic covers off to get to the rad front from the top.

If you think it's the air hole , swap it out. It's super easy and cheap

all that 1/8 th inch hole does is let the system bleed air better. its not gonna flow enough coolant past it to make a difference.

unless your rubber seal around the t stat is missing, then coolant would pass the t stat id think.

I know that but just saying if you truly believe it's the culprit - change it out