Is my thermostat bad?

[Ayc3]

On my way to work today I noticed my engine temp get up to 240 degrees. I switched on my heat and it went down to 220. It's normally around 216 degrees and had already replaced both upper and lower hoses and replaced pump and belts. Not sure if this is normal or if something else is wrong. Any ideas? Thanks in advance.

 

[Trunk Monkey]

Not normal. 216* isn't normal either (unless you're towing, uphill, AC on, middle of summer). If you didn't burp the system after replacing the hoses you may have an air pocket, start there first. If that doesn't work, start cheap with the t-stat, then the radiator.

 

[nissanh]

^^^
Also how old is the radiator?

 

[Ayc3]

Burped the system stayed under 220 with A/C and 90 degree weather in Vegas. Is there something else I could be missing to bring the temp down?

 

[jerryb]

 

[2001LC]

I just tested two thermostat in boiling water. One in a 07LC 172k miles opened 9mm, the other from my 01LC 168K miles opened only 8.5MM. My eyes and thermometer where not good enough to get a good "start" to open test result. I replaced both thermostat, which was a 5 minute job, probably worlds easiest vehicle to do. Neither engine ran hot, based on instrument panel cluster temp gauge. Both they were original thermostats' from factory. But I could certainly see if thermostat Not opening properly engine could run hot!

If all this checks out: no clog in coolant system, good 50/50 mix Toyota antifreeze, no air in coolant system, water pump not leaking, good thermostat, good radiator cap and water temp sending unit. If all good, then start looking elsewhere like fuel starvation.


One interesting note:
Thermostats had different parts numbers and price. 01 was ~$19, the 07 was ~$31. They look Identical and both 82C.