47-55.1 Lincoln Cooling Fan

[Hcb3200]

since your pulling it to put in a gasket.
Do the flow test with straight water. makes less of a mess and you are not running it long enough to boil over with that cold water it won't over heat.
Run it idling see what flow is and run it about 1500 and see what flow is.

Then drain and hook all up normal and fill with proper fluid mix assuming the flow is normal and has not sent you off in a issue to troubleshoot.