Gurgling in engine bay after shutdown, upper hose empty

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borgille

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There are times I really feel like just taking a baseball bat to my truck! Today, after I got home after an uneventful 30 minute drive from work and turned off the truck, I heard some loud/noticeable gurgling coming from the engine bay. At first, I thought it was one of my kids thrashing around above the garage in the dining room. It kind of sound like when you hold a full gallon jug of water upside down as it drains. Popped the hood, and it sounded like it was coming from the engine or the upper coolant hose. Probably lasted for a good minute or so. Felt the hose...there's not really any pressure in it, and it doesn't feel like there's any liquid in it either. So, I open the radiator cap, and there's no coolant at the top, but there is coolant in the reservoir. I'm guessing the gurgling might have been either coolant boiling or air getting sucked in from the empty upper hose into coolant behind the thermostat...but not sure why air would be getting sucked into it. The coolant temp on the dashboard was at around 215 or so (3.6 V6 engine) just before I shut it down. Afterward, I slowly filled the radiator with maybe a quart slightly more of distilled water before it seemed full again. The upper hose got pretty hot after that.

I'm thinking one culprit might be a new radiator cap. Last week, I noticed a small leak around the radiator cap, so Friday, I got a replacement. The radiator was topped off when I swapped the caps. Could the replacement cap be responsible for the loss of coolant? I haven't seen any coolant leaks anywhere around my truck. Nothing on the garage floor. I didn't see any new traces of dried coolant on the neck of the radiator around the cap. I'll probably have to pick up something to pressure test the coolant system. Any other things I need to check? If it's the cap, I'm going to be pissed...seems like everything I get for that truck is faulty.
 

grizzstang

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Could be the cap if you bought a cheap one. It also could be your radiator.

The rad leaks around the end caps when they get old (where the plastic meets the aluminium).

You won't see it on your floor either but if you take a flashlight and check your rad you will see the staining if it has been leaking.

Start by trying another cap to see if that is your issue and it could be since you said your reservoir tank had coolant but the rad was low.

That should not happen with a properly functioning rad cap but do have a look at your rad.
 

GTyankee

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Radiator cap has to be the correct pressure rating
OEM is always the best

There is a possibility that you did not bleed the air from your system all the way


another video, goes into more detail

 
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borgille

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Yeah. It was definitely the cap. I returned the cheap one and got one from the dealership, pressure was good after that. I also replaced the crap thermostat from one of the local auto parts stores for an OEM replacement... still different than the aluminum housing original part, but that got the P0128 code to finally go away. I'll just keep checking the level in the rad and the reservoir until I'm confident that everything's good.
 
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