KING

In another thread, I went over this with another forum member, but I think I need to dedicate this problem to it's own thread, here it is:

I'll be driving to somewhere, I get there, shut the engine off, and after about 40 minutes when I turn the engine back on, the temperature needle gets up from where it's laying to the middle and twice has it gone over the half-way mark, though not to the "HOT" part.

However, when I start moving, as you may know, the water pump starts working so the needle positions itself to normal reading, and rarely does it move, unless a long stop a at light or something, in which it moves to a tad bit below the half-way mark.

Keep in mind, that I live in PHOENIX, ARIZONA and during the summer it can get pretty damn hot. With the A/C and stop and go traffic, I know it can be a hustle for the YOTA. Still, I'm not comfortable with what it does.

I hope this is not a symptom to future blown head gaskets.

Los Gatos?

Mine did that the other day! It scared the **** out of me, as mine has never done that before (or since) and has always run at EXACTLY the same point on the temp guage once it is warmed up...but nothing bad happened and it dropped down real quick, it was only there for a second...not sure why, I assumed the guage was being a skank.

denverbikeguy

When was the last time your coolant was checked or changed?

If it's been a while, get your cooling system power flushed and refilled to get all the little nasties out of there and make sure you're operating at full potential.

Sucellus

I always thought this was due to the heat that builds up in the engine while you drive. When you turn off the car, the radiator fluid stops circulating, the fan stops blowing to cool off the fluid, and whatever excess heat that was making it's way through the engine block dissipates throughout the engine and actually raises the engine temperature somewhat while the car is off.

If I am understanding the situation properly, I think all cars behave in this manner. Though in colder weather, the engine continues to radiate heat due to the large temperature difference with its surroundings, and thus the engine does not show appreciable temperature gain. In AZ in the summer, where the atmospheric temperature is much closer to the engine temperature, I can believe that you would still see a higher reading after 40 min.

On a slightly side note, I believe this is why electric fans often continue to run after the engine is off.

jx94148

I wouldn't worry about it unless it gets near the red area.

When the motor is shut off the water pump stops pumping. All the coolant in the block gets pretty hot since its not moving, then on a re-start all that hot coolant flows past the open thermostat and temp. sensor giving you the entertaining readings of hotter than normal and then normal again.

Using 107* Arizona air to cool 200* coolant in a radiator will never be very effective. Your thermostat will almost always be wide open. Since the A/C condenser is right by the radiator some heat will be exchanged between the two while stopped, adding to your strange gauge readings.

I think all of this was taken into consideration by Toyota when they were engeneering your truck. After all, they did sell these trucks in the hottest parts of Africa.

As long as it stays below the red line you should be OK.

dave89144

every vehicle I have been in here in Las Vegas during the summer does the same thing. Its just the coolant that stays in the block when you turn the engine off absorbing more heat. Its not circulating, so it just sits their getting hotter.

rimpainter.com

I have never experienced this on any of our many vehicles here in PHX. - and I watch my gauges very carefully.

Not to put a damper on what others are saying, just letting you know my experiences.

KING

I'm not taking any chances. I am having the radiator flushed or either cleaned out. I am also changing my thermostat and possibly going with a lower temperature............ 165??

If that doesn't make a diffrence, then I don't know.