ENJIN HEATING UP
 

My 1997 Nissan hardbody blown top gasket 2x.
Now back bearing went but oil pump working.
In front of fan is a unit with vanes--looks like it can heve some fluid inside with a spring sensor (for heat). What is this and can it be faulty or must the liquid inside be changed as I suspect this unit is faulty and oil was heating up
Thanx
What other engine can be installed?
Chris