Tip: Reason for overheating

Just wanted to give a tip for anyone who may overheat. I drove about 10 miles today and my truck (2006 Siliverado) hit 260. My first thought was 'thermostat', so I replaced the thermostat... still overheated. So I did some calling around and 1 suggestion was a bad head gasket, which didn't thrill me. However, I spoke with someone at a local parts store who suggested that I may have air in the line somehow and that I should burp my system. Turns out that's all it was. I had taken my truck for an oil change where they left the reservoir cap off. I did not realize it was missing for a week or so wich may have been all it took to get air in the system. So, if your vehicle overheats and it's not the thermostat, try burping the system before you go too deep.

Just how did you "burp" your system.

Just how did you "burp" your system.

Actually, my buddy "burped" it while I was inside making some more calls. While I was out there though, one thing he did was he held the hose coming from the top of the radiator that goes to the motor as the truck heated up, which held back (most of) the coolant. When my temp hit about 220/230, he released it so the coolent had a "burst" into the motor. Then, when I went back in the house, he left the cap to the reservoir off, let the truck heat up to just where it would get to the top of the reservoir and then shut the truck off. This was apparently bringing the air pocket to the top of the system and then finally out, because after he did this about 3 times or so it now runs like a charm. Ran it for about 20 miles this morning and it stayed at 200 the entire time.

Just how did you "burp" your system.

the proceedure to rid air on the 5.3 l engine is to keep cap off engine to idle, until the temp is in the normal range...as the engine runs coolant must be added...until it is at the full hot mark....


the lube jocky that did this is another example of how these forums get weird problems....I hope he used dexcool as you may know dexcool is more expensive...this is also how vehicle owners trash talk dexcool....



you should have had the coolant light on !!!!! so as to warn you of this....your engine could be damaged.....make sure you report this to the lube center in writting ...just in case..

you should have had the coolant light on !!!!! so as to warn you of this....your engine could be damaged.....make sure you report this to the lube center in writting ...just in case..

I'm not sure an air bubble in the block preventing 100% coolant circulation would throw an error.

I don't think there's a sensor that would register that except for the temp showing less than efficient cooling...

I'm not sure an air bubble in the block preventing 100% coolant circulation would throw an error.

I don't think there's a sensor that would register that except for the temp showing less than efficient cooling...


in the recovery /fill res... is a float..if the cap is off the coolant will move up and down so much that the coolant level sensor should show a problem..


the other condition that could have caused the overheating is the fact that you had no coolant pressure....it you had a hot day driving at high speed there is a great possibility the the coolant started to boil and then the temp was shot to max because the water pump could not pump air bubbles created with the boiling...

Update: Turned my heater on this morning and (I'm guessing) there was an air bubble still in there because I overheated again. This time I personally "burped" my system, and I burped it until I saw NO bubbles left. Even though my reservoir showed full originally, after burping (slowly) I ended up putting almost a full container of fluid in my truck.

disclaimer: not a certified tech by any means
How To: (turn on your heater while doing this) Standing with 1 leg out the door and 1 on the gas pedal, I could see my reservoir tank perfectly while able to control my throttle. Since my motor was already really hot, first I would simply turn my truck over and see the antifreeze being sucked in to the motor and I would immediatly turn the truck off, doing this would immediatly result in the AF returning to the reservoir along with air bubbles. Then after doing simply turning the truck over showed little results, I would pump the throttle to about 2500RPM+/-, which would suck the AF into the motor and return air bubbles. Once pumping the throttle showed less and less bubbles, I began holding the throttle around 2K-2500RPM and waiting. Once all of these stopped resulting in bubbles and my motor temp stayed constant, I was good to go. Keep in mind, during this process, if your reservoir begins to rise to about 80% or so, shut off the motor and let everything settle back down. Also, as you see air bubbles leave, this means there will be space for more AF, so make sure you keep adding AF to your reservoir as needed. Also, you will more than likely overflow a few times so be sure you're in an area where you can stand to drop some coolant, or be sure to clean up if needed.

[quote=KahneFan]Update: Turned my heater on this morning and (I'm guessing) there was an air bubble still in there because I overheated again. This time I personally "burped" my system, and I burped it until I saw NO bubbles left. Even though my reservoir showed full originally, after burping (slowly) I ended up putting almost a full container of fluid in my truck.

once again the proceedure to rid air on the 5.3 l engine is to keep coolant cap off, engine to idle, until the temp is in the normal range...as the engine runs coolant must be added...until it is at the full hot mark.....

If you still overheat and air is in the system the reservior cap should be replaced and also a pressure testing to ensure that the system is with no leaks...


usual causes blown head gasket , cracked head, intake gasket etc....