Temperature Gauge Indicates That The Engine Is Running Too Hot

[amateur]

Hello Everyone,

I just purchased a used 98 LS400 which has 31K miles and a clean record. The temperature gauge points to around 2/5 of the whole range and I thought that it is normal since I have driven many other cars beside Lexus; other cars seem to have temperature point around 1/2 of the range. The seller did not indicates to to me there was a problem with a car. By a chance, I read a owner manual and found out that the temperature should below 1/5 of the range. With caution, I open the radiator cap of the resevior and I only see very small amount of pressure as a result. I thought to myself if the engine is running as hot as the temp gauge has indicated, I should see a lot of pressure build up. I want to check the temperature sensor but I do not know the spec and I do not know how many of them on this car. Have any one has an experience with this problem? I like to think that the previous owner made an honest mistake of reading the temperature gauge like I do, but with uncertainty and assuming I will have to pay a heavy price to fix the problem, I am beginning to think that I have been crossed. <_<

[1990LS400]

High pressure does not build up in the coolant reservoir. It certainly does not on my similar 2000 LS400. And my temperature guage generally is below the 1/2 mark too. If you have not done so already, I suggest you take your car to a Lexus dealer or indie Lexus specialist and have the car thoroughly checked out. I would hope that the coolant has been changed by the calendar schedule since it is low mileage. If the coolant temperature is off, the most likely culprit is the thermostat - quite inexpensive.

[wwest]

High pressure does not build up in the coolant reservoir. It certainly does not on my similar 2000 LS400. And my temperature guage generally is below the 1/2 mark too. If you have not done so already, I suggest you take your car to a Lexus dealer or indie Lexus specialist and have the car thoroughly checked out. I would hope that the coolant has been changed by the calendar schedule since it is low mileage. If the coolant temperature is off, the most likely culprit is the thermostat - quite inexpensive.

My '92 LS400, now at 120,000, runs just a tad above the 2/5 point on the gauge, always has, rock solid there.

Look at the cold vs hot marking on the reservior, if the coolant moves up and down in that "range" from engine COLD to hot then you're probably okay.

[Sanpete]

The 98 owner's manual shows the "one fifth" mark as the lower end of the normal range. Mine runs at the "two fifths" mark.

If it hasn't been been done, you should consider replacing the timing belt and water pump. The timing belt is supposed to be changed every six years, and it's generally a good idea to change the water pump at the same time. You could have them inspected, at least. You might find better prices with equally good service at a Toyota dealer rather than a Lexus dealer.

[paulo57509]

The temp gauge on my '98 LS400 runs at a steady 2/5 up from cold....right on the line.

I think you're fine.

[DanW]

Hello Everyone,

I just purchased a used 98 LS400 which has 31K miles and a clean record. The temperature gauge points to around 2/5 of the whole range and I thought that it is normal since I have driven many other cars beside Lexus; other cars seem to have temperature point around 1/2 of the range. The seller did not indicates to to me there was a problem with a car. By a chance, I read a owner manual and found out that the temperature should below 1/5 of the range. With caution, I open the radiator cap of the resevior and I only see very small amount of pressure as a result. I thought to myself if the engine is running as hot as the temp gauge has indicated, I should see a lot of pressure build up. I want to check the temperature sensor but I do not know the spec and I do not know how many of them on this car. Have any one has an experience with this problem? I like to think that the previous owner made an honest mistake of reading the temperature gauge like I do, but with uncertainty and assuming I will have to pay a heavy price to fix the problem, I am beginning to think that I have been crossed. <_<

By '2/5ths' I assume we're talking about the second mark up from cold.

The temp never stays below 1/5th for very long, even when its 0 degrees out. Mine runs close to or at 2/5 most of the time, just a hair over when its like 100 degrees out. It's not really even warmed up until 1/5th. Sounds like your car runs fine.

The ls400 is a little bit quirky...there will be many more non-problems to worry about but ultimately you'll love owning it!

[VBdenny]

Mine sits just a tick or two below 1/2 and has never moved in either freezing winter or heat of summer.

[amateur]

Hello Everyone,

I just purchased a used 98 LS400 which has 31K miles and a clean record. The temperature gauge points to around 2/5 of the whole range and I thought that it is normal since I have driven many other cars beside Lexus; other cars seem to have temperature point around 1/2 of the range. The seller did not indicates to to me there was a problem with a car. By a chance, I read a owner manual and found out that the temperature should below 1/5 of the range. With caution, I open the radiator cap of the resevior and I only see very small amount of pressure as a result. I thought to myself if the engine is running as hot as the temp gauge has indicated, I should see a lot of pressure build up. I want to check the temperature sensor but I do not know the spec and I do not know how many of them on this car. Have any one has an experience with this problem? I like to think that the previous owner made an honest mistake of reading the temperature gauge like I do, but with uncertainty and assuming I will have to pay a heavy price to fix the problem, I am beginning to think that I have been crossed. <_<

[amateur]

Hello Everyone,

I just purchased a used 98 LS400 which has 31K miles and a clean record. The temperature gauge points to around 2/5 of the whole range and I thought that it is normal since I have driven many other cars beside Lexus; other cars seem to have temperature point around 1/2 of the range. The seller did not indicates to to me there was a problem with a car. By a chance, I read a owner manual and found out that the temperature should below 1/5 of the range. With caution, I open the radiator cap of the resevior and I only see very small amount of pressure as a result. I thought to myself if the engine is running as hot as the temp gauge has indicated, I should see a lot of pressure build up. I want to check the temperature sensor but I do not know the spec and I do not know how many of them on this car. Have any one has an experience with this problem? I like to think that the previous owner made an honest mistake of reading the temperature gauge like I do, but with uncertainty and assuming I will have to pay a heavy price to fix the problem, I am beginning to think that I have been crossed. <_<

Hello Everyone,

I thank you very much for your input. It is a comfort feeling when some members indicate that their LS 400 temperature gauge is at the second mark from the cold. The temperature range in the manual was making me very nervous. Thanks again everyone.

[VBdenny]

I will have to check my manual, never noticed that