On May the 13th, 2019, I got a new raditor and thermostat installed at Firestone. Everything was good for 6 weeks. On a Tuesday morning going to work, the van started overheating. I pulled over, turned off the van and waited for it to cool down. Once cooled down, I checked the coolant level at the radiator and the coolant was low, the reservoir lid was open and was at the full mark. I put antifreeze in it to the bottom of the radiator neck and closed the reservoir lid. It ran fine going to work. After work, the coolant was low again and I filled it up again to the bottom of the neck. Next morning I filled it up again and took it to work. It started overheating again. I pulled over and turned on the heater and the temp gauge came back down to normal. Knowing that I filled up the radiator, I took off on the road again and everything was fine. I have repeated this for 2 more days with the same results. Seems that turning the heater on trips something and everything works ok. I changed the radiator cap and it still does the same thing. I have water in the reservoir. I checked the oil cap & dip stick and I didn't find no milky stuff. Checked the muffler and there was no antifreeze in it. I have no visible leaks on the ground or around the inside of the engine.
Update: Took van to Midas today for another check. They said most likely it's an air bubble and that Dodge vehicles are notorious for that. Could air have gotten into the coolant system when the reservoir lid was open?
I am perplexed.
Please advise.
Thanks.

 

if the system has a rad cap on the radiator; the reservoir is not pressurized so the cap for the reservoir is to keep dirt out...doesn't matter if its off or on for system operation.

if the system uses a pressurized surge tank (no rad cap on radiator)...the cap on the tank must be tight.

modern cooling systems should be vacuum filled to eliminate trapped air. adding coolant by hand to an empty system will require thermocycling to remove trapped air.

 

If you have a van with rear heating lines, sometimes, the van needs jacked-up one corner at a time, then lowered to the ground again to allow air to make its way to the radiator, or as close to it as it can. Air pocket do get created, so people have to get creative to move them around and dislodge them. Jacking-up the vehicle high, in various sequences, often does the trick.

 

You can get a coolant/antifreeze system pressure test tool from the Loan-A-Tool program at Autozone or O'Reilly Auto Parts.

With the van cool you put the test tool on the radiator cap spot (the tool becomes the radiator cap) and you can pump it up and see if the system holds pressure. If it looses pressure you have to look for the leak (engine is still cool). If not loosing pressure you would then run the engine until it's hot and then shut off the engine once it's hot to see if something is leaking when expanded from heat.

If still no leak then you have trapped air and you just have the fun job of finding out where and maybe bleading the air out from a hose clamp on the high points throughout the system.

 

You're supposed to fill the reservoir, run it to operating temperature, fill more, run more, etc, etc. Sounds like the just filled it once and sent you on your way.

If it's not leaking and holding coolant fully now, you're good to go. If it's losing coolant and all you did was replace the radiator and thermostat, I'd be looking for an external leak somewhere. My ram 1500 leaks. I can smell it, I think I know where it's leaking due to the buildup on the hose but I've never seen it wet. It must only leak under pressure.

 

Thanks for the info.

 

Thanks for the info.

 

Thanks for the info