My van keeps overheating

Could be a bad thermostat. Take the thermostat out and put the hose back on without one. If it stay cool or cold then the thermostat is the problem

Bleed air from system like this remove cap from overflow tank fill with antifreeze to full mark leave cap off and start vehicle and let idle you will notice level in tank start to rise this is normal once thermostat starts to open level in tank will drop add more antifreeze to full mark then put cap back on.