After replacing the Evans with Prestone there is no change whatsoever.
Is it possible that the new thermostat is incorrect? It’s this one:
My car was originally a US SPICA car, but a previous owner changed it to twin Dell’Ortos.
When I crack the bleeder open, hot or cold, only fluid comes out. An IR temp gun shows 185-200 on the exterior of all hoses, and there is heat in the cabin. The hose to the expansion tank is not blocked.
Still, the temp gauge shows a consistent 15-25F increase over the pre-top-end-rebuild temps.
If the car is parked with the engine running and the electric fan comes on, the temps drop verrrry slowly. I’d expect them to come way down in just 15-30 seconds based on experience with other cars, but it takes way longer. Same if I let the temps rise a bit then cruise at 50 mph — the temps don’t come down fast like I’d expect.
Is that a clue?
I really doubt the thermostat is defective. Could I have the wrong one? Unfortunately I no longer have the original.