bakadv

Hi, new here and hoping someone can point me in the right direction.

I've got a 2004 Chevy Impala. For the past year, I've had issues with the “Hot Coolant Temp” warning light coming on.

When this happens, it comes out of nowhere - I'll be driving along and then suddenly the "Hot Coolant Temp" light will come on, then within about 30 seconds, the needle gauge will creep all the way over to the far right. The car seems fine - no noticeable signs that anything is actually wrong with the car. (I don't think it's actually overheating.) But if I keep driving, then after about a minute, the a/c will start blowing hot and the gas will seem like it's getting cut off - the pedal gets "sluggish" and the car is not able to accelerate. The only thing I can do is pull over on the side of the road, turn off the car, and wait. If I try to restart the car immediately, the light comes right back on, but if I wait 10 to 15 minutes, I can restart the car and everything will be back to normal and I can usually get to where ever I was going without it happening again.
A few times when it's happened while I was stuck at a red light (and therefore unable to move the car to a spot where I could turn it off), the engine has cut off. But I was still able to restart it immediately, and drive to another spot where I could park it and let it cool down.

It does seem to happen more often when it’s hotter out (so more often when I'm driving home from work at 5pm, rather than in the morning when it’s cooler), and it also seems to happen more when I’m driving at low speeds (up to 30 mph) in stop-and-go traffic, or sitting at red lights and boxed in next to other cars putting off heat. (I live in Dallas, Texas, so it's about 100 degrees on my commute home.)
However, it's also happened when I was driving to work in the morning, when it was only about 75 degrees out and I was going 60 MPR on the highway. And once it happened while I was just parked in a parking space in the shade with the engine and A/C running for a few minutes.

So I honestly don't know if there's a correlation, or is something is just randomly glitching.



I've been back and forth between two different mechanics, both fairly trustworthy shops highly recommended by friends and coworkers. (However, I am a young woman and I don't really know much about cars, so there's certainly a chance that they're taking advantage of that.)

In the past 6 months, the following has been replaced: the thermostat, the thermal coolant regulator, the intake manifold gasket, the starter coil, and the catalytic converter. They've checked the radiator and said it was fine. They suspected a coolant fan, but couldn't find anything wrong with it.

I just had it in the shop again a few days ago, because my Dad suggested that it might be the air mass flow sensor. They cleaned that, and also replaced the coolant sensor - they said that the coolant sensor was telling the car that it was overheating (when it wasn't) and basically telling my car to shut it's systems down.

That seemed to solve the problem for a few days, but it just happened again on my drive home yesterday. I really need to get this resolved - so far I've been fortunate that I've been able to easily pull over each time that it happened, but I'm really worried that one of these days it's going to happen at the wrong time and place, and it's going to cause an accident.

Thanks in advance for any suggestions or thoughts!

Frank3

bakadv, this is really giving you the run-around. If you are driving around at highway speed, the fan will become less of an issue to keep the engine cool, since air flowing into the grill from the car moving forward should provide the airflow to cool the engine. Is there anything in front of the radiator or ac condenser but behind the grill that may be blocking airflow, like a plastic garbage bag or the like? That happened years ago to one of my cars. If the system is not air-bound or have air pockets in it, I would have it checked to see of there are traces of exhaust gasses in the anti-freeze. There is a test for that as well as pressure tests to see if you have a blown head gasket or cracked head. Remotely you could still have a bad coolant sensor as I went through 3 new ones in a row that were bad from the dealer. Please let us know what you find.

bakadv

Thanks! Just got off the phone with the service dept of a Chevy dealership and he said that he suspects either the gasket head (even though the intake manifold gasket was just replaced a few months ago) or that there could be a cylinder head issue causing the oil and coolant to intermingle.
He said the way to check for that is to see if there's condensation on the inside of the oil cap. I went to check, and there wasn't, but I did notice that my coolant tank was almost empty! When the car overheated on my way home from work yesterday, the tank was full, so it dumped the coolant out at some point. Also, the coolant looked a little dirty, despite having just been topped off at the mechanics 3 days ago, so I'm thinking it might be the cylinder head issue. If that's the case, he said the repairs will cost more than the car is worth. :/

Will check back and let you all know how it turns out!

Frank3

bakadv, you also have an option to go to an independent repair shop which may be cheaper. Just need to find a good one.

bakadv

Thanks, already been to 2 independent repair shops but they haven't been able to solve the problem, just racked up my credit cards with over $1k in repairs that didn't fix it.

That being said, the Chevy dealer service shop sent me home yesterday with no more answers, because they couldn't get the car to overheat or the light to come on. They want me to bring it back and leave it with them an entire day, in the hopes that they will be able to replicate the situation.

So, no one knows what's going on.

Frank3

bakadv, here's a nice comprehensive article about blown head gaskets, their symptoms, causes and how to detect them. Maybe this will help in you getting it diagnosed and fixed. (Not an endorsement of any particular repair service just used as a reference information.)

AGCO Automotive Repair Service - Baton Rouge, LA - Detailed Auto Topics - Symptoms of a Blown Head Gasket

Mike7896

Did you ever figure out what was wrong and causing this problem?

Irish_alley

well im not sure if they ever did. but i cringed when i was reading their original post about driving it and kept driving it even with the warning lights on and temp gauge in red. i would create your own post with your own issue