Replacing thermostat

[Keith.Williams]

Is it necessary to bleed the coolant system while changing the thermostat

[Blackened300a]

Is it necessary to bleed the coolant system while changing the thermostat

Yes, everytime the coolant system is opened. You can crimp the hoses to the thermostat to make less of a mess and less coolant loss. You'll still have to burp it when finished.

[fastblackmerc]

Yes you should burp anytime the cooling system is opened. You'll have less headaches later on.

[Motorhead350]

This is true. ^^^^^^