Good afternoon everyone.
I recently purchased a 98 ranger with 120k miles. Great condition. It has the 2.5 manual transmission. The thermostat was sticking open on me so I ended up replacing the whole thermostat housing with a new thermostat. Tried bleeding the system by leaving off the radiator cap and the coolant reservoir cap and letting it run with the heat on. I noticed some air bubbles coming out

Problem is after I've been driving for 10-15 minutes my temp will rise but if I turn the heat on it will go back down. I let it idle for 20 minutes this morning even ran up the road and back home with no issues. Get on the interstate heading to work tonight and it starts to overheat.

I'm thinking I still have a air pocket somewhere stuck. Plan on jacking up the front end and trying to bleed it that way tommorrow morning. I did it before on flat ground not jacked up.

Any ideas would be greatly appreciated. Thanks.

 

Edit: check engine light came on for a EGR A insufficient

Not sure if that has anything to do with it overheating or not. Also heard some bubbling in the radiator when I turned it off. Heat works.

 

After making sure it is bled properly, I would spray out the radiator fins from the engine side to get the dirt out. If the symptoms continue, they suggest an internally plugged radiator or perhaps a blown head gasket. Try the easy stuff first. It might be helpful to mention which engine you have