Overheated today

[CooLManZilla]

Hello everyone,

I decided to wash the car today, before I started it I opened the hood and did a general check.
For some reason I unscrewed the coolant reservoir cap, peeked inside and closed it back up.
i washed and dried the car and then took it around the block a few times to get the excess water drops out of the crack and crevices. I parked the car and let it idle while I dried the last few drops and dressed the tires. I noticed the fan come on but I didn’t think anything of it initially. After I hear the fan come on again I decided to peek at the temp gauge. Sure enough it was higher than normal. I quickly got in and backed it into the driveway and turned it off. I popped the hood and checked the coolant level. It was right at cold full. I squeed the upper coolant hose (it was hot but not burning) and it didn’t seem to have much pressure and gurgled back into the reservoir. Think it’s just a bad thermostat? Im pretty sure there is air in the system but what would have caused this sudden intake of air into the system?
car is 04 with 108k miles. All stock except for mufflers.

[Comin' in Hot]

You probably sucked air into the cooling system... only open the plug on the cross over tube(COT). you will have to burp the system from the COT plug

[CooLManZilla]

You really think just opening the reservoir while the car was off and cold would have introduced air like that?
I’ve never heard of that having a undesired effect before.

[Comin' in Hot]

Yes, Ford should have never put a cap on the marauder reservoir but its a shared part with the CV and MGM.

[CooLManZilla]

Can you please explain further? Ive never of heard of the cap having such an impact on air in the system before.

[Comin' in Hot]

The COT is the highest point of the cooling system on a 4v, not the reservoir. If you open the reservoir you have the potential to suck air into the cooling system. If there is air the system, it will eventually get trapped in the COT and thats where the temp sensors are causing the temp sensors to read high.... The system needs to be burped at the COT plug. Link>>>>> Ford 4.6L DOHC Coolant Refill & Burp Procedure by Reische Performance Products (https://www.reischeperformance.com/refill.html)

[Blackmobile]

This could come in handy

https://www.amazon.com/dp/B0BJDJG289?ref=ppx_yo2ov_dt_b_ fed_asin_title

[CooLManZilla]

Thanks. I’ve seen and read about the burp procedure before. I had the car towed to a shop, they did tests, checks and burped the system. Car isn’t overheating anymore but I noticed a few air bubbles percolating in the reservoir after i got home. So I am assuming there is still a little air left in there still being forced out. I’m nervous about fiddling with the COT myself too much since they seem to be impossible to get. I would rather leave that to the professionals.
on a another note, what’s the go to radiator replacement for our cars these days? Mine is still the original and I want to be prepared when the time comes to replace.