Reply to "Some good...some bad! It passed the MoT test ... But it over heated on the way home."

For what it is worth, my process when filling an empty system is roughly this:

First off, a stuck thermostat is a MAJOR problem. Whenever I have my Pantera coolant system opened, I always replace the stat. Always.

AND, with the thermostat pipe removed and everything is open, I fill the engine block at the thermostat location all the way to the top. That little trick removes a LOT of air from the system before you even start the engine.

Install the stat and the stat pipe.

I then install the Lisle spill-proof funnel in the pressure tank fitting and start to add coolant to the system at the funnel.

Air trapped in the radiator can be bled at the radiator, or on cars like 2511 that have the air-bleed hose running back to the pressure tank, that trapped air is free to bleed out of the pressure tank.

Once filled, start the engine. Funnel is still in place, and filled at least half-way with coolant.

Run engine until warm enough to open thermostat. Since I prefill the block, the stat opening does not noticeably affect the funnel coolant level, but if no prefill, expect a quick drop of the funnel fluid level as coolant is allowed to enter the block. WATCH TO MAKE SURE THE FUNNEL DOES NOT EMPTY.

Eventually, the funnel coolant level reaches a steady level and very few air bubbles are being seen rising from the bottom of the funnel. You are almost done.

Shut off the engine.

As that hot coolant cools, its volume shrinks and the funnel coolant level will lower as the system refills itself to a cool state.

Wait for everything to cool down.

Put the funnel 'fluid stopper' in the funnel, remove the funnel and install the pressure tank cap. Check that the expansion tank is about 1/3 to 1/2 full.

Done.

As I take the car back onto the road, I always check the system several times after this process, but rarely need to add any coolant.

The funnel is readily available online or locally for less than $30.

I need to acknowledge Jack DeRyke for bringing the Lisle funnel to my attention, many years ago.

Larry