Greetings fellow Lexus owners. I hope this doesn't seem trivial but I've got a 2007 yes and the temperature gauge goes up to exactly halfway and doesn't move after that. What I mean to say is shouldn't a temperature gauge show some fluctuation with the changes in engine temperature? Because this one doesn't move a millimeter from 182 212 degrees and to my mind that's wrong? When will it move when it hits 250? I believe a temperature Delta of 30 or so degrees should be reflected with some movement of the gauge. As it is now it's acting like an idiot light. So what I'd like to know is is that just the way it is or do your gauges move with different changes in temperature because at this point I feel that I cannot rely on the gauge to warn me of an overheat situation. Any input would be greatly appreciated because it's a little bit warm where I live.

 

How do you know the temperature goes from 182 to 212°F if the gauge doesn't move? I may have missed something.

A steady halfway needle is the expected behavior. This is what I noticed with all the cars I went in, including my GS. It should obviously move if the temperature varies, but a car with a working cooling circuit will have a gauge settling halfway.

 

I’ve owned quite a few Lexus and other Toyota products, and the needle has always been pretty much in the middle of the temp gauge. A healthy cooling system shouldn’t really show any variance.

 

If you have fluctuating coolant levels maybe your coolant level is low, or clogged. Many other brand cars, if the coolant is low, the coolant sensor reads funny. Temp sensor needs constant flowing cooling to properly gauge the temp.

Have you ever replaced water, thermostat, and coolant flush? If not, its best to replace all three of those items for preventative maintenance. As the GS is weak in handling overheating, and many have blown head gaskets or completely destroyed their engines. Check also for pink slime anywhere around the engine, the radiator, the inside of the water pump pulley. Toyota coolant once dried turns into a pink crust, that crust means you have coolant leaks.

Parts are cheap, and labour is easy but will take about 2 hours. You can diy it, as there are videos online. Many of us have used Aisin brand water pump (oem relabeled) as there only $90 bucks on rockauto.com

 

Its supposed to gradually rise, as the engine is warming up. At around maybe 190-210 degrees the thermostat opens up and really lets the coolant flow through. But when cold the thermostat only allows a pinhole of fluid to flow, this is designed to quickly bring the car up to operating temperature.

 

Hi PauloFR,
Thanks for the response. Usually the temp runs around 182 to 192 F. I know this because I use the Torque app and I can actually see the temp. I have only seen the big
temp change one time as I was sitting still with the AC on for an extended period of time. Torque showed I was at 212 F. I put the car in motion and the temp dropped back down to 192. However, the temp gauge did not move at all. Not by a whisker. Here's the thing, from my point of view a temp gauge should, based on how sensitive it is, show variations in temp. How else are you to know your car is getting hot and possibly approaching an overheating event? When or at what temp will it move? Or will it move at all. Even in the best cooling system I submit that temp is not static, it's dynamic. Wouldn't you agree that sitting in traffic on a 104 F day that your temp might rise a bit and as you make it to the freeway it will go down. I guess its in the sender. I have had mechanical temp gauges -Auto Meter- and others and they move depending on conditions, ie. sitting still, moving etc..

 

Hi ibidu1,
Thanks for the input. I will be doing a flush and fill. No leaks spotted and the GS does not use coolant. Well over the course of a year I have added maybe a pint to the recovery tank. There is a slight deposit right around the recovery tank lid. At no other time have I seen the temp go that high. I use the Torque app so I can see the actual temp. When this happened it was 104 F outside and I was sitting for an extended time with the AC on. When I started driving the temp immediately went down. I just feel that the gauge should be a little more dynamic.

 

Admittedly, the gauge should move especially for a raise as big as 30°. Although in my GS, whether it was 70 or 100 outside, the needle staid perfectly in the middle. I could record with my BlueDriver one time to check myself how it behaves, but this is a very unusual problem. If the OBD data reports the right temperature, this isn't a sensor nor a computer problem.

So it could come either from the needle, something else on the dashboard, or there is a use case which engineers have not thought of and the computer doesn't know what to do with the gauge, but all of those options are very unlikely.

 

So I saw this message looking for information on my GS350. So the other day our city was hit with lots of snow. Cold, like 12d. On the drive home, my heat was not getting warm and I knew the coolant was low. I had reluctantly not filled it the day before. After the first 15 minutes, the engine temp gauge shows 1 notch away from 1/2, as it always did. Now I got stuck in snow traffic while my feet froze. Now I use an OBD WiFi gadget and Touruq app with an android radio. I noticed the temp in the app was going up over 200 degrees. I was getting nervures because I could not pull over and the Lexus gauge was at about 1/2 now but not going over that. The Touruq app was starting to show 229d now but the Lexus was the same at 1/2.
After about 2 minutes the Lexus gauge started to clime and Touruq was now at 235d. when the Lexus gauge suddenly started to climb up fast and I have never seen it do that. Lexus gauge was now over 1/2 and at 3 notches from RED line.

Touruq shows 237 and Lexus is at the 3ed notch from RED when suddenly, the Lexus temp gauge started to drop, fast.. In about 1 min is was again at the 1/2 mark. The Touruq app shows it dropping fast but not as fast as the Lexus gauge.
Odd as it was the temp came back down to about 189. The thermostat had opened at 235d or so. I continued to not have internal heat moving at 2 miles per hour.

After I made it home I let things cool and then opened and filled the top of the block. I would race the engine and then fill it again. It was maybe 2 cups low but that's all it took. I have heat in the cabin at idle again.

I am thinking I need a new thermostat because I bet the OEM original is in it.

Thas all.

Thanks.
RS.

 

cooling systems are pretty darn efficient these days. if the needle is moving, something is wrong.

 

Have you replaced your water pump aswell? The water pumps on our cars are known to fail at 90k miles + or -. So what many of us do is just replace the pump, theres a brand called aisin, they make the water pumps for toyota. They can be had for about $80 to $90 from rockauto.com and only take 2-3 hours to install. You allowing the car to overheat you risk warping the cylinder heads and ruining your head gasket. I would do a full cooling system revamp and do the thermostat, water pump, idler pulley, serpentine belt, and new toyota 50/50 coolant.

 

So I replaced the thermostat on the weekend. The engine in my GS 08 seems fine. No misfiring. So far the engine temp and new thermostat are working very good. Driving to work in cold weather and I have not seen overheating in fast or slow traffic. However another development, the driver side air is cold after the engine has warmed to about the first 2 notches on the temp gauge. The passenger side air is very warm (almost hot) with the same gauge reading with the car sitting still, not driving. After driving for over 15 minutes the driver side is only slightly warm but the passenger side has hot air out.

I will start a new thread in the 3ed Gen area in the forum.