Replaced surge tank, now erratic temp guage

[RKL2]

I replaced the large plastic surge tank in my Cat 2006 Journey (36GD). I followed all the suggestions on this forum and it went well...In disconnecting the old tank I probably lost about 1/2 gallon of coolant after disconnecting the main radiator hose....
When I hooked everything back up and added new coolant I went for a drive to heat it up and burp the air...During the drive, the temp gauge kept going up to normal and down about a quarter and then back up to normal...It lasted for about 15 minutes and then stayed at normal...
I thought it was trying to remove any air pockets and when I returned home I removed the coolant cap on the purge tank and quite a bit of air and some coolant blew out. I also had turned the heater control on during the drive and heat came out the vents.
do I need to do anything more to ensure no more air pockets?...Should I take it for another drive to test the temp guage?....thanks...RKL2

[MrTransistor]

Hi RKL2,

I think you’ll be okay. You may want to take another 25 mile drive to see if the problem is gone before you attempt another long trip. If anyone finds a better replacement for this tank, please ‘scream it loudly on this site’!