Operating Temp 98 vs 01 Lexus ES300

[coppens1]

 Dear fellow Lexus owners, my 01 Lexus ES300 runs a lot hotter than my 98 Lexus ES300.  Both have the same engine.  The 98 temp gauge shows in the very low area, and the 01 shows medium.  

The 98  Lexus radiator capacity, 9.2 L, or 9.7 Qt

The 01  Lexus radiator capacity, 8.8 L, or 9.3 Qt

That .4 qt shouldn't make such a big diff in operating temp.    Does anyone else have this problem with the 01 Lexus?  JC
 

[Lexus Owners Club]

I would be tempted to measure the actual temperatures of each engine with an infra-red thermometer to get an accurate reading.

With the engine temperature sensors used on both engines maybe reading differently but as long as they are within tolerances then no fault codes will be created.

[coppens1]

Dear Trevor, Sorry it took so long to reply.   I missed the notification that you had responded.  There definitely is some difference in the two radiator systems.  In fact, I have to add water every 6 months, to the 01 Lexus ES300, but I have never had to add any water to the 98 Lexus ES300.  JC

[Lexus Owners Club]

If you are having to top up the coolant on a frequent basis then I would imagine it is doing on of about three things.

Burning coolant - you would notice white smoke (steam) coming from your exhaust on a constant basis (e.g. not when cold as this would be the cat working on open loop)....this could be the headgasket or cylinder liner cracked

Losing coolant - you would notice a leak on the floor or inside the driver footwell. Also check the engine oil is not mixing with coolant (mayonaisse looking substance).....heater matrix or hose, etc

Coolant pressure cap on the coolant reservoir is defective and the coolant pressure is not being maintained.....this is the first one I would check and also the cheapest.