Overheating issue

[Aveo5_boy]

I thought I would pass this info along as i was browsing through the Chilton Manual.

Engine overheating checks from Chilton Manual:

Check for a loss of the coolant.
Check for a weak coolant solution.
Check the front of the radiator for any dirt, any leaves, or any insects.
Check for leakage from the hoses, the coolant pump, the heater, the thermostat housing, the radiator, the core plugs, or the head gasket.
Check for a faulty thermostat.
Check for retarded ignition timing.
Check for an improperly operating electric cooling fan.
Check for radiator hoses that are plugged or rotted.
Check for a faulty water pump.
Check for a faulty surge tank cap.
Check for a cylinder head or an engine block that is cracked or plugged.

[daltron]

I thought I would pass this info along as i was browsing through the Chilton Manual.

Engine overheating checks from Chilton Manual:

Check for a loss of the coolant.
Check for a weak coolant solution.
Check the front of the radiator for any dirt, any leaves, or any insects.
Check for leakage from the hoses, the coolant pump, the heater, the thermostat housing, the radiator, the core plugs, or the head gasket.
Check for a faulty thermostat.
Check for retarded ignition timing.
Check for an improperly operating electric cooling fan.
Check for radiator hoses that are plugged or rotted.
Check for a faulty water pump.
Check for a faulty surge tank cap.
Check for a cylinder head or an engine block that is cracked or plugged.

First of all, thank to you to everyone in this thread who has posted and thank you Aveo5_boy for typing that out for me.

Good news: I found the leak. The small outlet of the thermostat housing is leaking, looks like an easy fix. The leak was too slow and did not leak under idle/2,500 RPM when parked so I didn't notice it before, but before the thermostat housing and down I can see the previous drops.

Bad news: The leak is small and isn't the cause of the overheating.

Check for a loss of the coolant. - Leak is small, found it.
Check for a weak coolant solution. - Nope.
Check the front of the radiator for any dirt, any leaves, or any insects. - Nope.
Check for leakage from the hoses, the coolant pump, the heater, the thermostat housing, the radiator, the core plugs, or the head gasket.- Leak is small, found it.
Check for a faulty thermostat. - I assume the thermostat is working because the upper hose is hot, and the temperature is hottest the at the upper hose/upper part of radiator, and cools down further down the radiator. The heater also works.
Check for retarded ignition timing. - Not sure how, but car "runs" fine.
Check for an improperly operating electric cooling fan. - Fan runs fine at a stop/in traffic and the problem also happens at highway speeds.
Check for radiator hoses that are plugged or rotted. - On my initial check everything looked fine.
Check for a faulty water pump. - Heater is working, and coolant temperature (tested with IR thermometer) goes from hottest to coolest from upper hose > top radiator > bottom radiator > lower hose, so I assume the circulation is working.
Check for a faulty surge tank cap. - Only cap is the pressurized reservoir cap, which I have already replaced.
Check for a cylinder head or an engine block that is cracked or plugged. - Can't see anything on the exterior, seems possibly out of my expertise but I am not sure how to check.

Other things to consider:

The temperature gauge slowly climbs to the red line. Turning the heater on brings it back to normal levels.

[avguy]

Good progress to be left with just a "simple" overheating problem now . Based on what you wrote, it definitely sounds like some type of blockage which is causing a flow reduction. Water is moving, but not fast enough to keep the temp where it's supposed to be. The heater core must be functioning as a heat sink, pulling off the excess heat and keeping the system in balance.
So here are the possibilities that come to mind. Broken water pump impeller - unlikely, and just about impossible if it's a metal impeller. Thermostat not fully opening - not as likely being fairly new, but possible. Radiator becomming defective - not too likely but possible.
The one other thing that I can think of is the possibility of a small object dropped into the coolant tank while you were topping off. Those aluminum sealers on the coolant jugs need to be peeled-off or punctured before using. I'm sure you're careful, but is there any chance that a piece of that aluminum (or anything else for that matter) dropped down into the jug? Some small object like that could have perhaps flowed to a location where it's now causing a partial circulation restriction. It seems like a smoking gun that the overheat started only after you began to top off the low coolant.

[daltron]

I don't think I dropped anything in there, but that's always a possibility. A blockage sounds like a difficult thing to pinpoint. Because of the low cost, I want to change the thermostat out just to rule that out. Pull the upper and lower hose, drain everything, check to see if there are any issues with that stuff and go from there.

[petrified.rabbit]

if you have a leak it is highly possible you have an air pocket.

how hot is it running? if the system is depressurized because of the leak it is going to run @ 20 degrees hotter than if the system is pressurized. If there is also an air pocket, it could actually overheat.

[daltron]

if you have a leak it is highly possible you have an air pocket.

how hot is it running? if the system is depressurized because of the leak it is going to run @ 20 degrees hotter than if the system is pressurized. If there is also an air pocket, it could actually overheat.

I believe the highest I saw, assuming the ECU/scan tool was correct, was 117c. I ordered the CA thermostat (apparently CA has a different thermostat temp....) from Rock Auto and when it gets here this week I am changing that out and redoing all the connections.

[daltron]

Long story short, last 24 hours: Was driving back to work yesterday afternoon in the Aveo this time to replace the thermostat when the temps shot up and the radiator blew out on the freeway. Had it towed to work and picked up another radiator.

Ended up replacing the thermostat, thermostat housing, and radiator and the car no longer overheats.

[avguy]

Glad to hear it's no longer overheating - hope the HG survived the stress. It may help others if you could post the model number of the rad that blew out on you. If I knew which one it was, I would definitely avoid that rad, if and when I have to replace mine.

[daltron]

Sunbelt Radiators SBR-2873.

SBR-2873 | Sunbelt Radiators Inc.

You definitely get what you pay for, I guess.

Thanks to everyone who posted in this thread and helped me out.