Most likely the thermostat...easy to replace and cost around $12 at auto parts store. You could check on youtube for instructional videos if you don't know how to change it.

 

Thermostat is a good first guess and the best place to start. The thing about it getting to normal op temp after 30-45 minutes is a little strange but sounds like something a thermostat could do.
http://autos.yahoo.com/maintain/repairqa/fluids_heat_air_conditioning/ques018_2.html

Do a radiator flush at the same time. Clogged radiators don't cool the fluid. Old and dirty radiator fluid can cause thermostat failure. Be responsible and recycle what you can of the old fluid. And don't let your pets drink it!!

Watch a youtube vid and DIY.

Non-operating radiator fans could also do it. When it's red-lining check that both fans are running.

 

Be a good idea to also test the coolant temperature sending unit - I've seen some cases where the cooling system was perfectly fine, just the sending unit was starting to die.

If you haven't done any coolant service on the car - be a good time to do it. The factory "red" coolant - I change mine every 2 years/30K miles. Is supposed to be good up to 60K miles, but IMO - that is pushing the coolant's capabilities. The "pink" stuff can last longer, different chemistry.

100+F degrees is nothing to the car. Some of the hot days we've had here in VA hit 105F ambient, with road surface temps approaching 165F at optimal sun angle. In DC Metro traffic - either haulin' at 80+ MPH or crawling around at a mile every 25-30 minutes - even with my little trailer - temps are always well controlled.

 

When the temperature spikes, does the cabin heater still put out heat?

Last month I had these symptoms on my '05 Chevy Duramax and it turned out that the water pump driven gear was spinning on the shaft that turns the impeller - meaning, no coolant circulation. This was an intermittent problem until the shaft lost a couple thousandths of an inch and no longer could grab the driven gear at all. The pump didn't leak, but the engine was not able to turn it due to the spun gear. If your heater isn't blowing HOT then I'd look close at the water pump.

The only thing changing the thermostats did was making my wallet $90 lighter...

 

I didn't know a pump could do that.

 

Neither did I.
Neither did anybody at the local GM dealer - they swore I had a bad head gasket. I suspected as much also, but the symptoms didn't really fit: there was no residual pressure after the engine cooled down. Removing the parts necessary to see the pump impeller showed that it wasn't turning when the engine was bumped with the starter.

The pump on that truck is a cast impeller pressed onto a shaft that has a driven gear pressed onto the other end of the shaft and the whole thing gets bolted to the front of the engine and buried under another hundred pounds of parts. Lots of inertia, apparently susceptible to quick RPM changes (gear shifts), and no key or D shape on the impeller to stop it from spinning loose - only friction. I keep a new pump in my shed now.

How are the corolla pumps driven?

 

No keys. Inner and outer bearings. Press fits. Impeller doesn't look like cast.

If my guage is running high, I'm going to first think thermostat. I'd remove radiator cap to observe flow. No flow confirms thermostat. Change thermostat. Problem remains. Now I think plugged radiator. Take radiator out. Check flow. Flows OK. Only one other possibility: water pump impeller (if you are aware it's possible). Don't know how you get to head gasket? Would not explain flow problem.

 

If my guage is running high, I'm going to first think thermostat. I'd remove radiator cap to observe flow. No flow confirms thermostat. Change thermostat.

I hope people don't misunderstand that part. Don't remove the radiator cap if your running high. You should only remove it when the engine is cold. If you want to confirm if the thermostat is working then feel the upper radiator hose. It should be hot.

 

Don't remove the radiator cap if your running high

Right. I wrote that too fast. In actual practice I would let the engine cool, then remove the radiator cap, then warm it up and watch for flow.

 

and if it is not hot, but the temp guage shows things ARE hot, don't open the cap. Coolant doesn't like to boil easily, but when it is hot enough in the core of the engine the loss of pressure will result in VIOLENT amounts of steam pushing all your coolant out. DAMHIK...

I think I've seen this -- "wonderin' when it's gonna stop..."

Head gasket symptoms: high pressure in cooling system pushing coolant out radiator (expansion tank) cap, overheating, cooling system stays pressurized (exhaust gasses) after engine is cool

I think a better way to characterize the difference between overheating-pressure and head-gasket leak pressure is when a head gasket leaks exhaust gas into the coolant passages, your radiator will vent coolant through the cap but the motor won't initially be over-heating. And, even before it vents through the cap, there will be bubbles if you remove the cap.

In post-mortem, i.e., in 20-20 hindsight, I would have also asked myself, when I felt stumped, why didn't I look for more clues, like, do something simple like check flow through the radiator? Even if it doesn't seem logical, more looking, touching and testing can reveal things. Sometimes you have to throw away a misleading piece of evidence. Look out for assumptions.

I think the main lesson here is to be very careful with diagnosis. It's like the carpentry motto -- measure twice, cut once. I had a long apprenticeship to "jumping to conclusions". Part of this was lack of comprehensive training, where you learn all the ins and outs of the systems on the car, so you have the "big picture" in your head. With a big picture, you are aware of all the possibilities that could cause the problem. You stop and make a list. Then stop and make sure the list is complete. Then attack the list. It keeps things in perspective.

Granted, the impeller thing is rare and creates a ripe situation for misdiagnosis.

 

Thanks guys. I guess i will start with changing the coolant and thermostat. Two questions. Is there a post somewhere about DIY changing the thermostat? Or maybe a video clip. I searched youtube, there are lots of video clips but didn't find any related to 8th gen. corolla.

I also found some documents on 99 corolla thermostat replacement, but all are just words and can hardly locate where is the thermostat according to that. Wonder if there is a pictured step-by-step instruction anywhere?

(from the shop manual it seems I will have to remove tons of different parts to access the thermostat housing, is that true? looks really complicated job)

Also, I found 180 and 170 degree thermostat in my local parts store, which one is supposed to be better? I am in Texas, should i get the lower temp one?

thanks soooooooooooooooooooo much!

 

I'm a BIG fan of AllDataDIY.com and the cheap subscription fee has been money well spent for my truck (guided me through changing head gaskets on my diesel), my Benz (valve adjustment), my daughter's Corolla (throttle valve cable to transmission), and my other daughter's jeep (brakes) so far.

Changing the thermostat looks like it's a fairly simple job: remove the serpentine belt, remove the alternator, a switch from the thermostat housing , the housing bolts, and you're in. Make sure the jiggle valve (a trapped BB sized ball) is up when you're installing it.

Take lots of pics with your cell phone when you're taking things apart, make lots of notes so you know what the pics are of.

Easy peasy!

Looks like the factory thermostat is a 76*C valve.

 

Thanks for the great information. Everytime I heared i have to remove this this and that to get the time i want, I just freak out. The best i ever done is replace spark plugs and coils. so removing alternator really sounds like a major surgery to me. LOL

 

Check out the repair instructions from autozone...it's almost similar to the 1zz-FE engine
http://www.autozone.com/autozone/re.../autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f803802a6

 

Working on a similar issue with my 98 corolla. Your post was dead on in regards to replacing the thermostat. Didn't fix my problem but certainly helped me accomplish what I was after.

 

my 1998 corolla does the opposite . it drives fine but heats up at idle goes almost to the red but then the fans come on and it drops down alittle. its annoying