Got my LS400 a few months ago, fantastic car and drives like a dream. One question on the engine temperature indicator maxes out at around 40%, which is right at the indicator mark below 50%. It never moves up beyond that no matter how much I drive. If I drive on the freeway at 60-70Mph, the temperature needle will actually drop down to around 30-35% and when I slow down or stop, the indicator will go back up to 40%.

Does your 90-94LS do the same thing, or should I change the thermostat? I have already changed the Engine Coolant Temp Sensor and it made absolutely no difference.

Thanks in advance for your response!

 

Sounds normal to me.

 

I would check to make sure you have enough coolant, but if so I don't think you've got a problem.

 

yep, normal. if it gets to 50% i would be concerned!

 

Good to hear it is normal, the coolant was changed about 2 months ago so no issues there. Was going to spend $$ to change the thermostat. Thanks for your response!

 

It is not normal, your thermostat is stuck open, i was having exactly the same issue 2 weeks back...
Check your thermostat and replace it if required

My problem solved by replacing the damaged thermostat!

+ Don't buy an aftermarket thermostat !

Normal temp reading would be in the middle which is = 86 Celsius

 

At highway speeds it is dropping down that much? I'm no expert but that does not sound normal. The normal for these cars or at least on our 3, is just a hair about the 40% ticker or third from the bottom.

Mat

 

Yes, when driving in the highway, it will drop down to 30% and will move slowly up to the 40% mark if I slow down or stop. Very strange as I never seen this on any of my other cars. Thanks for your input, I am going to bring it to my mechanic and have a more detail look.

 

when was the last time the thermostat was changed? usually it's done during the 90k timing belt/water pump service. if it was never done, it would not hurt to do so.

 

Not sure when was thermostat last changed. The timing belt was changed 20K miles ago in 2009. Maybe it is time for a new thermostat.