The impossible to solve overheating problem

90% of these "overheating" posts have one thing in common. A small electric fan such as yours, which is totally inadequate

.............and no fan shroud/or inadequate shroud, to force pulling air through the rad, and not around it.

Although you have found (or your new mechanic) other issues causing your overheating problems.....that little fan and no shroud is not helping you cool anything........you might want to upgrade to duals and proper shroud to eliminate future cooling problems.