172, overheating

[JMBW]

hi

Every time i turn on the heater, my coolant gauge goes through the roof and when i turn it off, the gauge goes down to normal again. And othervise the gauge is somewhat unsteady (bobs a little)

could it be the coolant censor or an airlook in my coolant system?
or maybe something else?

please help me, it's driving me crazy!

 

[sideways danny]

sounds like an airlock to me

 

[not normal dan]

sounds like air lock for sure maybe in heater matrix

 

[JMBW]

Thanks,

Is it something I can flush out myself or do I have to take it to the shop?