mhuitt

1999 Chevy Cavalier (4 door, 4 cyl)
Over the past few weeks I've been having an overheating problem with my Chevy Cavalier.

At low speeds (on the city streets) it tends to start overheating. You can imagine the anxiety when I come to a stoplight or traffic jam. I've been forced to turn it off when I come to a stop on city streets. If I don't, the heat gauge will jump up (but not into the red) and the car will die. If that happens, I usually have to wait a good fifteen twenty minutes before I can get it going again.

This does not happen on the highways. I get on the highways (I-35 here in Austin) and start going 40+ - it'll cool down to what I'm used to (slightly below the mid-way mark on the heat gauge).

I thought it might be the relays, and I found another website saying to switch with the heat blower and if the heat blower works - it's not the relays. So I did that, the heat blower worked - so I guess it's not that?

It was suggested I start and idle the car in my driveway, checking the fan. The fan never turned on. But, it does turn on when I go around 40+ mph (or so I attribute to the fan the cool down when I hit that speed).

Liquids are all topped off (was done when I got an oil change a month ago) - and checked just a few minutes ago, no fluids needed.

Any help on this problem would be appreciated.

mikeschopshop

check your hoses by squeezing them they should feel firm. if there soft or hard replace them. your thermostat might be stuck closed. a way to test this is to disconnect your hose from the thermostat while its coldand start the car and once its heated up to operating temp it should open. but that should be a last resort test only because coolant is a hazardest cemical and if it gets into your soil and they test it it will become a hefty fine so i sugest if you do it to drain your coolant itno a bucket and put only water in your system then test it. but make sure to drain the water out when your done. a simpler test is to just remove the thermostat and try to compress the spring you should be able to do it by hand and it should be firm and not to easy. if its to easy then it will be opening at the wrong time. also the reason it cools off at highway speed is because the air flows faster over your radiator and helps cool it off and on the streets you dont get much airflow. another thing you should check is your radiator fins just look at the radiator and make sure theres no major dents in them this could cause the fluid not to flow.
this is only to help not a 100% diagnosis

hattonr

Hi all! I am kinda stumped on this. I inherited this car over a year ago and it's been fine, though I was told by my aunt who bought it new that her mechanic said it needed a thermostat. She just stopped driving it and it sat in her garage.
I drove it around my town a while after driving it home about 100 miles. One day, after using the car about a year, i was leaving my mom's house (where I originally picked the car up) and it overheated withing maybe 10 miles. Sat a whe and was able to get home on the highway with the guage at the max operating zone, diving with the heat on full on 90 degree weather.
replaced the thermostat and flushed the whole system... no rust or chunks came out and everything seemed fine. Drove from PA to NC and all around for over a week and 1500 miles without issue, running the ac the whole time. Came home and it sat for a while, then I used it for a 5 me ride and it overheats... changed the radiator and it seemed fine. Drove it back to my mom's yesterday and fine for about 80 miles, then the temp shot back up. Finished the trip with heat on full blast and the temp just below max.
coolant level is fine. I tested the original thermostat and it's fine. The fan runs at the proper time and it gets hot in town as well as at highway speed. The heat is crazy hot...
would a water pump cause something that intermittent? Sure seems like a sticky thermostat... and I know new does not always mean functional, but 2 thermostats causing the same problem?
seems more like cavitation, but one would think that after 100 miles and no change in fluid level, the bubbles would have worked through.
This has been my spare car and currently has o ly 55k miles on the 2.2/auto.
oh, never in an accident and my aunt always had it dealer serviced until she was unable to drive.
Any thought would be appreciated!

Bob H

Jiyu

My thermo stock on me 10 years ago so I simply removed it - never hat an overheating problem since. Random overheating when everything else is (apparently) fine sounds like a faulty thermostat. Just take it out and run without one for a few months. It only takes about ten minutes to remove. If the water hoses feel 'crunchy' when you squeeze them, get new ones.
Wouldn't hurt to do a coolant flush. If the car sat most of the time there could be corrosion in there.

hattonr

Already replaced the thermostat once, also did a full extreme flush. On the Cavalier 2200, it uses the thermostat with an integrated gasket (round rubbery basket that goes around the thermostat), so you really can't just remove it. That was my next try - I am going to take the OLD thermostat (I saved it and it tested fine) and cut the "workings" out of it so it flows free. If THAT seems to fix it, I think I will install a 160 degree thermostat. I know it's not a great idea to modify the manufacturer's designed operating temperature, but since the engine blew in my Suburban i am really relying on this Cavalier a little more than I prefer!

Cavvy

What I ended up doing after replacing the thermostat didn't solve the issue was bypass it altogether and now I have an engine fan on/off switch right under the steering wheel. I turn it on in slow traffic or if the AC is on. If it's a ton of slow driving however, I have to turn off the AC and sometimes even turn on the heater in the summer to vent the heat off of the engine. This is not super common, but it does happen on really hot summer days if I'm sitting in line at a drive thru etc. Normally not a big deal, especially in the winter or with freeway driving. That's how I handled it. Another issue is if you forget to turn the fan off and kill your battery, which has happened a few times.

hattonr

Yeah, that doesn't work for me. If I remove the thermostat, the car NEVER warms up. I mean ZERO heat in the winter and it barely comes to operating temperature when it IS hot out, even sitting in traffic at idle. This thing is killing me because it's a great car, I just can't trust it!
So... no thermostat - never heats up. I have been through 3 thermostats and each one seems to work a while, then overheat. Testing in a pot of water, all thermostats work fine. It's almost like the thermostat simply never sees that the engine is warming up. I have tried every "burping" technique I can locate to remove all the air from the system.
Oh, and when the car overheats, the heat in the car blows HOT, so the coolant is circulating, it seems just not to the radiator.
When everything works, it's fine, but that's rare.

Jiyu

Interesting.... Bad temp sensor or bad temp gauge? Old radiator hose that cannot hold its shape, that is, one than collapses when it gets hot? Coolant system not fully purged of air? An old radiator hose that is deteriorating internally causing periodic blockages? If the hoses feel 'squishy' that's no good. Also check that none of the coolant hoses are pinched or bent. If you haven't done a coolant/radiator flush, you should. I did mine recently and a huge amount of rust/silt came out. Whatever it is, it's probably something simple. My guess is a hose-related problem.
Remember, the more mysterious the problem the simpler the cause.

hattonr

Everything is good. When the gauge says cold, there's no heat, when it says it's too hot it's boiling over and heat works. Flushed everything, replaced hoses, radiator, temp sensor and 3 thermostats. It just seems new thermostats are pure junk. I took one apart and put in a couple brass washers so it can't close all the way and now it at least warms up a little. Doesn't quite get to operating temp ALL the time, but pretty darn close. I actually started test with a brass nut and that held it open too much and now down to 2 washers. If it annoys me, I'll go down to one washer. Fortunately, I don't have to drive the car too much, but man, this is an odd cooling system Nothing really seems to be wrong except the thermostats stick and don't allow coolant to flow to the radiator.

Jiyu

Maybe there's a nut loose between the seat and the steering wheel....