At my wits end, motor getting hot. Input please

[lil hoodlum]

At this point I think I have covered most of the common reasons.


It may very well be someting that I am overlooking or not correct on. New thermostat may not be working properly.


Motor is some 18 years on rebuild so there maybe a build up of scale or whatever inside. What does anybody recommend for cleaning it out?


There very well maybe a blockage some where in the motor, intake, heads, etc. I am not opposed to ripping the intake and heads to verify and install new head gaskets to rule out old ones leaking. Oil is not milky. Antifreeze/coolant is a nice green color.


2nd question.
Could valves be in need of adjustment cause a motor to run hot?