hi all,

my 98 es300 does not reach what i think is normal operating temp, in the middle of the gauge. It appears to stay cold no matter how long i drive it.Sometimes it comes up a little about a quarter of the way but thats it. Can i drive it this way without it causing any harm to the car? And am i correct to say that it is a faulty thermostat?

 

You can drive the car in the short term but you'll waste gas. If you keep driving like that the engine will never got hot enough to burn off moisture and you could end up with a sludge problem. The thermostat is probably bad.

 

thank you for the quick response. Do you know if it is a difficult job or something the average person can do?

 

Not a terribly difficult job I find it more annoying than anything quite a lot of stuff in the way. Speedkar has a video on it, guy seems to have a video for everything. I highly recommend you use an OEM thermostat part number 90916-A3003 the extra $5-10 is worth it.

 

The normal operating temperature of all engines is around 85 degree C. A quarter of the gauge is roughly around 55-65C.

This might be normal if your present local climate is quite cool, and you are using the AC (runs fans), or

- if the lower or upper fan switch (or both), has failed and lost continuity, causing both engine fans to run at 100%, 100% of the time.
- if someone has disconnected either of the switches to solve an over heating problem AND your local climate is quite cool.
- if the dash gauge is faulty.

I could easily be wrong here, but my understanding of thermostat failure is that it causes the engine to retain the water, which would display as over heating.

But, if the temp sensor is after the thermostat, and the thermostat is fully closed all the time, or mostly closed, seeing low temps might make sense. (I haven't checked before posting, too lazy)

 

You can have a faulty thermostat or a faulty temperature sender (thermometer).
First thing first, make sure there is no air in your line.

 

Faulty thermostat could be stuck closed causing over heating or stuck open causing too much cooling.
or the temperature sensor is faulty sending the wrong information.

I would start with the thermostat, easy and cheap to replace. it should throw a code, it did on my friends avalon. 2000

 

Try connecting an OBD scanner to get a live temperature reading. If it's around the 80 Celsius that ES300NZ quoted, you can look towards the instrument cluster being faulty ($20 at a junkyard, just gotta swap the odometer part to keep mileage).

If it's not reading 80, move onto changing our temperature senders and thermostats like others suggest.

You can probably rent an OBD scanner from local auto part stores.

 

ok, i will try to get an obd scanner. One more question, are both fans suppose to be running? yesterday, while looking at the engine i noticed neither fan was running.

 

The fans only run when

You turn the a/c on
Or when your car reaches a certain temp

When your temp guage reaches the middle you'll be at around 185 Fahrenheit, the fans turn on around 203 Fahrenheit. The temp gauge doesn't move at all though until 230 ish Fahrenheit. At least in my 99

 

Ok, i thought at least one of the fans would be running at all times. Car runs great with no issues except for gauge reading low temp. Probably a quarter of the way at most.

 

the fans will only trip and start running is the engine reaches 'operating tempature' which is set by the resistance of the fan switches (look like sensors), the switches alter their resistance from 400ohm to 0ohm, 200ohm's is 85 degrees C. Those switches are very sensitive (and caring :P) the moment you turn the motor on they resistance starts falling as the engine warms the fluid it uses for cooling. I suspect (but haven't checked), that the second fan only turns on when the AC is running, or if the engine temp rises about a certain point (which I don't know).

This low temperature situation might be explained by someone using a high tech modern cooling fluid. The MCV-20 (es300), cooling system is so good that will keep the engine at around 100 degree's C without the fans at all (hot enough to damage things over time, cool enough to stop it overheating, at least for a while). Its got such a large radiator and great airflow with an alloy block and excellent engine bay air venting. I suspect if one of those modern non water based cooling fluids was used it would have result like this.

 

Thats very interesting. I took it to a mechanic yesterday and he said it was ok. Not sure if he right or not.

 

To add to the other's comments, did you check the coolant level by removing the radiator cap (not just checking the recovery tank) and does the heat work?