Thermostat Change

[DemonDaz]

I am planning on changing the thermostat this weekend. When I drain the system, if I drain from the bottom of the block, do I need to drain from the radiator as well?
I will also change the blue thermostat while I'm at it.

[delphini]

What temp. thermostat are you putting back in it ?

[Brianmoooore]

What temp. thermostat are you putting back in it ?

The same temp that came out i should hope, unless someone has been messing before.

[Brianmoooore]

I am planning on changing the thermostat this weekend. When I drain the system, if I drain from the bottom of the block, do I need to drain from the radiator as well?
I will also change the blue thermostat while I'm at it.

Drain both if your planning on a full coolant change. Personally I would just pull off a bottom radiator hose.
You haven't said what engine. If it's a six pot, then refill with the front of the car slightly uphill. Turn the heater full on and monitor the temp gauge and heater output when you restart the car. Airlocks are common and cause severe overheating.

[DemonDaz]

Cheers Brian, it is a 6 pot, 325.
Full coolant change, when filling up, Bentley manual says to fill then open the bleed screw, would it be better to just leave the leed screw open until water comes out of it?

I will pull the hose off the bottom of the rad.

Any other tricks to prevent air locks?

It was a thermostat from ECP, 80 deg I think.

[Brianmoooore]

The troublesome airlock happens at the back of the head in the heater circuit. It's not normally a problem to shift it, but if you don't know about the possibility, and just start up the engine, it can overheat in a surprisingly short time, with the possibility of cracking the head.