I had my timing belt replaced yesterday and while taking things apart my mechanic noticed my thermostat had been gutted, so he threw a new one in.
Before it would take quite a while for my engine to warm up. Sometimes upwards of 30 miles on a cool morning. Obviously this would kill my gas mileage since the transmission wouldn't kick into overdrive.
Well today when I got in the truck, it was warmed up in about 10 minutes and about 1.5 miles and some idling at a stop light. I was worried because it happened so fast so I kept an eye on it. The gauge didn't budge past it's usual spot just to the left of center. Same behavior on the way home about 5 hours later. Warmed up fast, then held steady. I'm happy because now overdrive kicks in fast and it'll save me some gas. I was just wondering how long it takes others 3.0s To come up to temp and if this is normal?

 

On a cold day, maybe like 45-50 degrees, I can start driving upon ignition and probably 2 or 3 mile later it'll be warm. I had that same worry as you at first. I'm guessing you have an automatic. I can put mine in overdrive whenever I like xDD

 

Yup, it's an auto. I was just surprised at how quick it warmed up this morning after driving it like it was for 6 weeks. REALLY glad OD kicks in sooner, saving me gas.

 

The engine still uses a ton of gas until its warm.

The cold start injector loves fuel. Wait a few min before driving off, it helps not only with gas mileage, but you have more power when its warm.

 

Cold start injector only fires a maximum of something like 15 seconds, and that's at the north pole in winter, lol. Normally I think 4-8 seconds. What costs the gas at warm-up is the ecu runs in open loop mode until the ECT reports operating temp. Open loop is both a warm-up and fail-safe mode, using preset values for mixture and timing that run the motor rich. When motor reaches op temp, ecu switches over to closed loop mode and starts using O2 and other sensors to calibrate mixture/timing, and the motor runs a lot leaner.

I think the open loop mode of the ecu on my 89 must be calibrated not quite rich enough; my motor will sometimes stumble if I try to give it too much throttle when cold. They may have changed the open loop calibration to run a little richer in later years, IDK. Mine runs fine once it swaps to closed loop, which only takes a few minutes. Basically, when you see your temp gauge register operating temp, the ECT should be giving the same info to the ECU and the switch to closed loop should happen at nearly the same time.

 

I've had two 3.0's and even when it's -40 below they would both start blowing heat within 5 minutes. These engines warm up quick and I really loved them for that because when it's -40 all you can think about is getting some heat!

 

If I start mine and just let it idle, takes about 5 minutes or so.

 

I just replaced my thermostat and radiator, and this summer my temp gauge has been coming up to its normal position in less than one minute of driving.

 

My '89 4Runner does the same exact thing when it's cold too.