I am having an overheating issue and it only happens when I'm on the freeway or long stretches of road, fine in stop and go traffic and idling. also it will not over heat if I turn on the heater full blast.
here is the back story
I was gifted a 2007 Dodge caliber SE with a blown motor, no issue for me as I have done many engine rebuilds and swaps.
I found a motor with 49k miles the motor swap went great, along the way I replaced alot of the gaskets since I was in there, I also replaced both thermostats and the water pump to prevent issues, and the motor I purchased, didn't have either thermostat or water pump.
finished the swap 3 days ago and the car started right up no issue did the normal bleed (burp) the cooling system went out for a few short drives no issues at all had the ac system recharged and the alignment done.
decided to take it for a 30 minute drive temps were good, jumped on the freeway and the temp started to climb using my obd2 live to monitor the temp it went up to 240 F so thinking when I was younger I turned the heat on full blast and with in 10 seconds the temp dropped to 205 f. so I went home let it cool down check the fluids and nothing was low, I squeezed the hose to make sure I got the bubbles out.
At the point I'm like ok maybe it was a fluke and its fine I started it up and let it sit in the driveway for 30 minutes or so it got up to normal temp 205 so I was like ok lets test drive it,
fine in town hit the freeway again same issue.
so I looked online to ensure I didn't miss anything like a trick or a bleeder valve.
got home let it cool down, pulled both thermostats out didn't see any issues but I replaced them just because they were under warranty, the system seemed to be full of coolant when I pulled it apart,
so I put it back together and filled it up again, and hit the road for another test drive.
same issue only over heats when I am on the freeway or long stretches of road but if i turn on the heater full blast or its stop and go traffic or idling I have no issue.
any help at this point would be much appreciated.