My engine has 120k miles on it, and is getting hot on the way home from work. The engine temp usually runs just over the 1/4 mark. It happens on hot days, over 80 degrees, after running on the highway about 15 miles with the a/c on, then getting into the city where I slow down and the temp needle shoots up over the 1/2 mark. It has never gotten in the red zone. It is unusual because I have run this route for 7 years, summer and winter, and it's never gotten much over the 1/4 mark..I did replace the ECTS and connector in 2015 with ACDelco parts.

A month ago the low coolant light would come on a few times, but it went out when I put coolant in. The reservoir tank level is a bit over the cold line, like a 1/2" inch over. Should I remove some down to the cold line? I wonder if maybe air got stuck inside when I added coolant? How would I remove an air bubble in the system?

When I turn off the a/c it gradually goes down to below the 1/2 mark, but doesn't get to the 1/4 mark. The oil level is to the mark so it's not hot from lack of oil. The electric fan works, no hose leaks anywhere that I see.

Would a bad reservoir cap or thermostat cause this?

Any ideas would be appreciated,
Thank you

 

Check the coolant level and make sure it's good. The coolant overflow level should be at cold when the engine is cold (sat over night). If those are correct, go borrow a pressure tester from your local parts store and check the pressure on the radiator cap. Unfortunately these cars have plastic radiators and you may have a small crack somewhere. You'll need to pressure test the radiator too. Once you pump up the pressure to 15 ( I think) you watch the gauge and see if it holds the pressure or slowly starts to drop. This usually takes 15-20 minutes to do properly, so be patient. Or it could be as simple as your thermostat is starting to go bad.

 

I don't see a cap on the radiator. The only cap I see is on the coolant overflow tank and it says 15 psi. I checked the level this morning and it's between the MIN and MAX Cold marks. Do I check the radiator pressure at the tank opening?

 

Make sure you're under hood cooling fan behind the radiator turns on when you engage the AC with the fan on. If it does not, either the fan motor is dead the relay for the fan is defective, there is corrosion in the socket or under the socket for the relay, or if ects is again defective which would be my last gasp since you replaced the connector as well, yes?

When was the last time you flushed out and changed the coolant?

Since you are not overheating your thermostat is not stuck closed, so I suppose it could be stuck partially open or not opening fully when the car gets up to temperature. When you are driving, the faster parts of your route, there is enough wind and The fan under the hood to dissipate the heat. When you get to the slower parts oh, you are losing the heat dissipation from the airflow. Therefore if the fan is not working, you have lost most of your additional methods of heat dissipation.

I would check the things I already mentioned first before going after the thermostat.

Also, is the air dam underneath the front of the vehicle intact and if not was it removed in the last few years? It is there to direct are directly up and across the radiator. If it is not there, again you are losing a very large source of heat dissipation.

I do realize there is no such thing as a source of dissipation. Sorry about that

 

Today I borrowed the coolant pressure tester from O'reillys pumped it up to 15psi and the pressure stayed steady for 1/2 hour. I could see no leaks. I also found that the radiator fan does not come on when the A/C is on and the interior fan is turned on. So I tested all the A/C fuses I could find in the kickpanel and engine compartment. All were good and I cleaned up the prongs for good luck. I swapped A/C relays with the horn relay and the relays worked the horn so they are good too. Then I removed the fan connector and it has 14.3 volts.

So it looks like the fan is dead ? Should the fan automatically come on when the A/C is turned on, even if the coolant temp is cold?

I probably should change the coolant, it's been at least 4-5 years since I did that.

Another thing, the air dam is on the car but not the spoiler held on by springs, which I've seen on some Youtube videos. Did I lose the spoiler or could the model I have not come with it? I never noticed if the car had one, I've had it about 8 years now.

 

Indeed sounds like your fan is dead. If you are in doubt carefully run 2 insulated wires to the positive and negative battery terminals. If it doesn't spin from that you know it's dead dead dead. You can also do a resistance check across the two terminals on the fan itself. I don't know what the resistance should be but probably less than 50 ohms.but if you read infinite resistance then it means it is open circuit and has failed.

The fan is absolutely 100% designed to come on when the air conditioning is turned on. Doesn't matter what the temperature of the engine is.

The spoiler with springs you refer to is what I was referring to as the air dam because that's what it is. You must have ripped it off running over something. Stuff happens. The springs rust and fail. When they work their way loose, one side of the air dam will hang low. Then you just need to run over something substantial and will usually break the other springs leaving the air dam on the ground behind you.

I would go to a junkyard and see if you can find an air dam and equally as important as many pairs of springs as you can. You need two on each side for a total of 4 but you can't buy them anymore anywhere so you probably want to get at least 6 if you can. I don't know if the coupes and the sedans shared the same frame by that time but I think they did meaning it would be the correct with and the spring holes in the right places whether it was a sedan or a coupe. You could look up the part numbers through one of the GM parts websites and see if they are identical.

The air dam is important with respect to keeping the engine cool. Especially in the summer twin driving without air conditioning. Without the air dam, the outside air is not forced across the radiator.

Also, you need to fix the fan ASAP because if you get stuck in traffic in the summer the fan will not kick in at all to cool the engine down when the temperature gets up to near the red. If you are stuck not being able to move and get air across the radiator he will likely overheat

Aftermarket fans are available. At least last time I looked for something else and came across them.

 

Rock Auto has fan motors for sale, I'll get one of them and swap it over. I'll be back in a few days when I get it installed.
Thanks!

 

I bought the fan off of Amazon since I needed some other goodies and it arrived yesterday . It took about 45 minutes to swap it out. What a difference! The engine is running cooler and the a/c cools off the interior quicker too.

 

That's great news. Thanks for letting us know you're running cool now.

 

Indeed thanks for stopping back in with the update.

Another s car saved from self destruction