What's the correct procedure for getting all the air out of the cooling system of a PV? I installed a new radiator and refurbed heater unit and also added a coolant recovery system bottle to the new radiator. After adding the recommended antifreeze & water I shut up the system and started her up. Temp shot up and started pushing fluid out of the radiator top cap. What should I be doing?

Thanks guys, VERY helpful. Will do what you recommend!

I have had to drain and refill my 544 system at least 5 or 6 times recently. I do it like Ron describes. Leave the cap off as it warms up and be sure the heater core valve is open as that is (at least in my case) where most the trapped air is hiding. I usually have to refill the radiator level once or twice as it warms up. I had a leaking heater core that didnt want to seal up despite repeated attempts to solder it up. Yea, finally got it to hold.
Dean

PVG;

I'd recommend keeping the Rad Cap of a newly filled Cooling System open until at least the first TStat opening so you can monitor and top up after the level falls, as air moves out...your temp "shooting up" was caused by a big bubble(s) of air which allowed hotspots (possibly local boiling) and which need to be replaced by Coolant...I'd fill Rad and pump on the hoses by squeezing even before starting the engine...and after starting also (CAUTIOUSLY, keeping bodyparts from moving engine parts!), by covering Rad with palm and again squeezing top hose and adding some shock and turbulence into the Coolant path for the purpose of dislodging air-bubbles.

"started pushing fluid out of the radiator top cap." ...this does not sound right! In a CS with Exp Tank the Rad cap is strictly a sealing cap, so NO Coolant should EVER even be able to come out here!...the Pressure (and overflow) is regulated, and allowed by a CS with ET, by the Pressure Cap which is now located on the Exp Tank. See also: https://www.sw-em.com/Cooling_System.htm#closed_cooling_system

Only after the majority of air is removed from the CS by letting engine run while Rad is open (and no pressure can build), and we monitor and manually burp and top up CS, and no more drop in the Coolant level is observed, should the Rad be sealed with its (Sealing) Cap, and Pressure Cap also can seal the CS on the ET (filled to Min level)...only then is the Auto-burp (Step 2 in graphic) able to handle what little air is left...before that, it would be completely overwhelmed by all the air (and that is what caused your overflow!).

I would say this info applies to B18/20 as well as B16 CSs.

Cheers!