Recommended Interval For Tstat Replacement?

[AZ Mike]

I have a low mileage '99 LS400; just passed 60K miles. I will be doing the 60K mile maintenance this weekend, including cooling flush and fill. I couldn't find anything in the Lexus recommended maintenance regarding the thermostat. Is there a recommended mileage/age interval to do so?

[wwest]

I have a low mileage '99 LS400; just passed 60K miles. I will be doing the 60K mile maintenance this weekend, including cooling flush and fill. I couldn't find anything in the Lexus recommended maintenance regarding the thermostat. Is there a recommended mileage/age interval to do so?

No.

Engine cooling control thermostats are reliable enough that most cars arrive at the wrecking yard with the factory originals.

But I suppose that you might as well if you get to 250,000 miles and want to finally change the original timing belt and maybe even the water pump.

[SW03ES]

Agreed, no reason to replace the thermostat.

[chilkoot]

if it makes you feel any better, the 1st gen thermostats fail open, so if it does go south the temp gauge sticks at the second needle and not the red one.

I can only assume that a '99 would be the same.

[1990LS400]

if it makes you feel any better, the 1st gen thermostats fail open, so if it does go south the temp gauge sticks at the second needle and not the red one.

I can only assume that a '99 would be the same.

All thermotstats are in the open position when they fail -- that's just how they work. That's why the first sign of thermostat failure is usually the lack of heat from the heater.

[eatingupblacktop]

I would replace the stat with every timing belt service.