'98 Camry Running Cold

If it isn't broke, ......etc

Not only that, the ECU won't enter closed loop, so the oxygen sensor and catalytic converter can get damaged from extended open loop operation. Not to mention some transmission won't go into overdrive when the temp is too cold. etc etc

You mean it did not close but open properly with heating?

Worn "heat motor" -- that wax bulb thing -- probably leaked wax out. When I changed out mine there was some waxy stuff at the top, so I assume it was the wax leaked out.

If you took it out with the timing belt/pump change it would be a good time to change the stat. But if it's working now maybe until the next coolant change.

I have the same problem Kari, what site did you use as a reference. I'd like to try replacing it myself.

This is coming a little late, obviously, but if you are going to pull a thermostat that old, replace it, don't test it. It could test fine and then fail 6 weeks later.

Sorry if I wasn't clear - the factory manual says to put the stat into room temp water and gradually heat it and measure the change in length near boiling. Figuring it would make no difference, what I did initially was boil some water and then dunk the stat in it for a while and then measure the change in length.

What I discovered is that if you don't heat the water gradually with the stat in it, the length doesn't change. When I heated the water with the stat in it, the length changed to what it was supposed to.

I was just wondering if anybody knew why the rate of heating affects the operation of the stat so much. I guess I just don't understand the principle of operation of the stat. Maybe I didn't hold it in the water long enough...

Thanks for the other posts in this thread counselling me to change the stat next time I change the coolant, which will be in a year and a half. (or sooner if I detect the symptoms that the OP was having).