So I saw that the caps that were on the bolts of the radiator were breaking from the heat so I made some new ones.

Print Settings  

Printed using Prusa i3 MK3S on the smooth spring steel sheet with PLA filament with these settings:

Layer Height: 0.3mm

Infill Density: 100%

I have not scaled down the model as it fitted perfectly.

You can always use different materials or settings, whatever suits you best.