Over heating issue - 4 Days until NC 500

Hi Guys
Need your help. I'm off to do the North Coast 500 with my fellow Scottish Region members. Ok bought a Lhasa green tin top last month. It has done 2000 miles in the last 15 years. I've renewed radiator, thermostat, heater matrix, water pump and gave the system a good flush. The old coolant had crystallised. Used Mr Muscle and drain cleaner to get most of the gunk out. Car is still overheating.gets hot really quick. Mechanic has taken the thermostat out and let the car get up to temperature. It's better but still hot. I've tried 2 thermostats so ruling that out.

Scratching my head and getting frustrated lol. Anyone have any ideas what the problem might be??

Cheers

hi is the fan kicking in mate

The t-stat has to match the temp rating of the radiator fan switch.

The Radiator Fan switch needs to be replaced and the new one tested that it closes at the designed temp.

Fans need to be tested that they spin, and that the +12 wire and the Ground need to be verified that they are good clean and tight.

No upper radiator card can allow engine compartment air to recirculate over the Radiator increasing the heat on the cooling system.  The upper radiator card prevents the air from being sucked in by forcing the air to only come in via the grille.

When filling the system if you didn't drill a 1/8 or 1/16th inch hole in the t-stat, then you can get an air bubble in the system that is hard to remove, I have heard of ones that have prevented the t-stat from properly opening.

You have to fill the system as from the radiator upper hose to lower block, then from the water outlet on the head in the front to fill the block. (heater should be on max hot as well.