It’s a shame there isn’t an air bleed valve in the top hose from the radiator. I had a Renault with one and it helped immensely to bleed air from the high part of the system, where it migrates to.
On the Plus8 (2002 model) the method above was basically what I used. My expansion tank was near the rad, not on the bulkhead though. I unbolted it, raised it up and it helped by being higher. Replaced when happy that airlicks were gone/ greatly reduced.Slightly overfilled to allow coolant suck-back as air was removed. Squeezing the top hose also helped get air from it into the expansion tank. Keeping the level in this expansion tank is important to stop air getting sucked back. Any excess will be expelled via the overflow pipe in the filler neck. The cap (15psi) released to let the excess flow out. Later level checks made after a few miles driving. I used 50/50 coolant/distilled water with water wetter.
Mine overheated once when stuck in traffic on a hot day and the fan fuse blew. Replaced the fuse and checked the wiring/thermo switch etc but no problems after that. The fan was always loud when on so an audio back-up to alert temperature getting up! I did some small jobs to reduce this. Making sure as much air as possible went through the rad ( Morgan ali not aftermarket). Morgan airflow leaves scopes for improvement! I believe the rad was slightly under spec as a heat exchanger as it was too near the limit for the thermo switch to kick in. The core should have denser gills per inch to increase hear transfer/airflow surface to marginally increase heat exchange, or even an extra row of tubes that would further increase heat exchange. This would reduce the times the fan kicked in. No overheating but enabling a slightly lower ambient running temp would give bigger leeway to the fan kicking in. Both these are standard upgrades. We used these in the radiator factory as basic upgrades for different engine sizes/ oil cooling/aircon differences for Rover SD1 cars as OE equipment for the assembly factories.
