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Bad thermostat symptoms?

Two symptoms make me wonder whether my 1994 Corolla has a faulty / sticky thermostat. First, in cold weather, when I ride at highway speed as the car is warming up, it seems to take a long time before the car kicks into its highest gear. I have an automatic, but in cold weather it doesn't seem to transition smoothly and quickly into its top gear.

Then the other day in the cold weather, the heater just didn't seem to be blowing out air that was as hot as it should be.

Sometimes the needle on the dashboard thermostat stays smack on Cold, and sometimes it moves a slight bit above it.

Do these symptoms point to a faulty thermostat?

If so...are there special things to be aware of when replacing it? I have put one or two in over the years in other cars, but I've never drained the antifreeze, etc. I've just put the new thermostat in and topped up the antifreeze. Thanks in advance for any advice.

Reply to
Al
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Yes, or a cooling fan that is stuck in the on position. When the engine is cold, make sure the electric cooling fan is not running.

When you remove the old thermostat, note the orientation of the spring and the jiggle valve, which looks like a piece of twisted sheet metal stuck into a small hole in the flange so that the replacement one goes back the same way. Clean the thermostat housing and mounting surface thoroughly, and use a new gasket. While you're at it, check the condition of the upper and lower radiator hose and heater hoses.

If the coolant is more than 2 years old, replace it with the correct concentration of new coolant.

Reply to
Ray O

My 95 1.8 had the same symptoms. The thermostat had a rubber gasket at the sealing edge of the thermostat that had folded over. the toyota replacement thermostat did not have that rubber seal. Could have removed the seal, but for the time spend, I installed the replacement. Well, my son in law did, but you get the idea.

I still have oil fouling on #4 that started at 5 years and 60k miles (1qt

400 miles, soot on bumper but no visible smoke). Now 11 years and 100k miles, I just replace plugs ever 10k miles or so when it starts to miss.

Reply to
Luba Papageorgio

I had similar symptoms when the thermostat in my Celica failed in the open position. It was intermittently faulty for about a month and then failed one winter night. When I got home the fast-idle was on! The wax capsule was still OK but the valve (which had a rubber seat) had partially fatigued through and had bent at an angle, so it couldn't close. It had a '93 date code on it and was obviously the original.

Reply to
Neil J. Harris

Sure sounds like it's stuck open. Replace it, you are hurting the engine this way. It is very easy to do, and the part is cheap. A cold engine is not a happy engine.

Reply to
RT

Hi Al, I don't know anything about the thermostat, but re. the transmission taking a long time to switch into 4th gear when cold:

I'm pretty sure this is normal. This has happened in my '89 Corolla (4 speed automatic) ever since I bought it in '99. At the time, I was also concerned about how the car seemed reluctant to shift into 4th gear when cold. I did some poking around and read in multiple places that the car purposely will stay in 3rd year to let things in the automatic transmission system warm up more quickly before going into

4th gear.

Hope this helps, John

Reply to
johnyang97

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