When to replace thermostat?

[Dohc98vteC]

Thanks for the replies, I have 157k on the clock I bought the car with 101k, Honda recommends 2 yrs on the coolant replacement, I have replaced it twice since I bought it, and it never was brown like in my brother's 93 Corolla. The hoses looks surprisingly good too, unless the previous owner had replaced them. I will be alright on the tstat for now.

 

[WishIhadatruck]

I'm getting rid of a '94 Grand Prix with 210k miles on it and I only flushed the coolant maybe 3 times in those years I had it (I bought it in '95). It still has the original hoses which look perfectly fine and I've never replaced the thermostat. It does need new intake manifold gaskets, brakes, tires, has a gas leak on top of the tank, it is rusting out but the cooling system is fine. Oh, the A/C quit working this year also. Actually all those things came up this year which is why I'm getting rid of it. I had it in getting brake work done a few years ago and asked the manager to replace the hoses when they flushed the coolant and replaced the water pump but he said they looked fine and they didn't. I never would have guessed hoses would last 13 years and 210k+ miles.

 

[Crashbox]

I've never thought of replacement as a PM item though if for some odd reason a certain model were prone to failure it would be wise.

Never had one fail "open" though a co-worker's vehicle did once- she was wondering why there was virtually no heat from the heater and the temp gauge didn't seem to budge... Better to fail "open" than "closed" for sure!!!!!

I usually only replaced t-stats when I wanted a lower operating temp in my engine; that was when I was a lot younger...

 

[Virtuoso]

All of the replacement thermostats I've installed (a few) have failed long before the OEM units they replaced in terms of milage. In fact, almost every one I've replaced has failed. This includes OEM and aftermarket replacements.

I'm due for a thermostat change in our Saturn as it's stuck open; but I may leave our Windstar's alone until it acts up. It still heats up nicely!