Forester08

I may be posting this is the wrong section but my car is a 2002 z28, during a roughly 20 min drive from work my ar only reaches 180F and drops to about 150F when im on the highway goin 60-70 mph, this is only when the temp outside is in the high 20s to low 30s at night. Im guessing its a faulty thermostat? Car heats up like normal in pretty much anything about 45 degrees outside during the day. Just wondering if anyone else has ever had this issue or if its a normal thing. My car does not have the aftermarket 160F t-stat either

Forester08

I do also still have heat as normal while all this is goin on

Paul Bell

iTrader: (9)

Welcome to LS1tech!

You got the right place to ask this question.

It sounds like you might have a bad thermostat. Do the fans run when this is happening?

Forester08

Not gonna lie, havent really checked. I'll have to look tomorrow night after work. But i usually start the car and let it warm up to where its at least showing a reading a hair above the 100F mark then ill start rolling towards the gate about 2 miles away and by then its about 150F and right off base is the highway so once i get on that it pretty much stays right around 150F then ill get to where the stop lights are closer to the city and itll get up to about 180F. T-stat change is no big deal, just kinda wanted another opinion on the matter before i went out and got the t-stat and all the coolant heh

Paul Bell

iTrader: (9)

Although I don't think it's common, if the fans are coming on too early, they could be "overcooling" your engine.

I'm leaning towards the thermostat.

Forester08

Think Im leaning the same way, ill change it this weekend and see how she does

Forester08

And thanks for the input!

sepsis

iTrader: (7)

Aren't there 160* thermostats and fans that come on at 160*?

I thought temperature in that range was desirable.

01ssreda4

iTrader: (96)

If the heat is hot your temp is wrong. I have a failed open thermostat on a DD currently and it takes a long time for the heat to work and the gauge to come up. Gauge and heater go hand in hand is what I'm getting at. In your case they do not. I suspect a faulty coolant temp sensor. That's what tells the computer where to put the needle anyway. I would confirm actual engine temp before yanking the thermostat. Where are you reading this temp from as the factory doesn't have the markings you speak of?

Paul Bell

iTrader: (9)

While I agree it may be a bad temperature sending unit, I'd still suspect the thermostat first as the OP said the temperature goes up then down. This would be the action of the thermostat.

Approximate temperature readings can be extrapolated from the factory gauge.

If this were my car, I'd change both items at the same time as the coolant needs to be drained for both.

Forester08

I'm estimating the temp to be in the ranges i posted based of the position of the needle, being that the first mark is 100F and the half way point on the gauge is 210F i just did a lil math and i assume the 1/4 mark on the gauge is 155F. On normal weather days where its not ***** cold the gauge goes right up to to its normal spot, just a hair below the halfway marking. Ill have to get a temp reader and match things up, although I know these temp gauges are known to be some degrees off from where the needle is anyhow

VandykeT/A

I can take my thermostat out and other than a little longer to warm up I still climb to 210 and stay there. I would bet its the sensor. The newer cars have dummy gauges anyway.

Forester08

well thats the issue, it only seems to "overcool" at highways speeds. It makes since i suppose being that cool air is being brought into the engine faster at those speeds. and if i just let it sit there and idle itll get right up to the 200F range

RevGTO

iTrader: (12)

My buddy's car w/160 tstat is like that in real cold weather. Mine with the stocker gets to normal operating temp much faster and stays there.

Redbull87

iTrader: (3)

I started having this problem aswell during the fall season and it was after I removed all my a/c components which left the rad wide open to cold air all the time.The car takes longer to warm up during the colder weather and once it gets upto temp and start driving..it will cool down to 150* or less.I just did the old cardboard infront of the rad about 45% covered the front of the rad and everything worked as normal again.Wasnt too concerned since I wont be driving the car in the winter..once summer hits then I take the cardboard back out.

Sounds like a new tstat and maybe the cts should be changed for reassurance on your end that both are 100% functional.

Forester08

Where is the coolant temperature sensor loated at?

Forester08

*located