What are symptoms of bad thermostat? (Corolla)

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Al - 07 Dec 2006 17:37 GMT

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.

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E Meyer - 08 Dec 2006 02:30 GMT

I didn't know Nissan made Corollas. Why are you posting this in the Nissan
group?

On 12/7/06 11:37 AM, in article
1165513068.426653.55910@73g2000cwn.googlegroups.com, "Al"
<acunniff@advancedbionutrition.com> wrote:

> Two symptoms make me wonder whether my 1994 Corolla has a
> faulty / sticky thermostat.
[quoted text clipped - 17 lines]
> thermostat in and topped up the antifreeze. Thanks in advance
> for any advice.

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Al - 08 Dec 2006 02:39 GMT

Oops. Sorry, I own a Toyota and a Nissan, and I got my newsgroups mixed
up!

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al - 08 Dec 2006 04:23 GMT

If the temperature gauge indicates that the coolant is not reaching the
correct operating temperature, then the thermostat is sticking in the
open position. The thermostat should maintain a minimum temperature.
If the engine is consistently operating below that temperature, the
thermostat has failed. I'd expect that if you sit at idle during
warmer weather, the temperature gauge will creep up to normal
temperature but will drop back to "cold" as soon as you drive forward
and get increased air flow through the radiator. Lower coolant
temperature will cause the ECM to run the engine and transmission as if
it's operating during warm-up.
The replacement is the same as you're familiar with. Once you find the
housing where the thermostat is located, you drain the radiator via a
drain plug in the radiator or by removing the lower radiator hose. You
might need a new gasket for the housing. I'm not sure about a 1994
Corolla but some Nissans require a bleeding procedure through a bleeder
valve in the engine block when refilling the system with coolant. My
old 1975 Corolla didn't have that bleeder valve. If you've done a
thermostat replacement before, it's still essentially the same process.
Good luck. Al

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