OK here is the thing my engine has been running at about 150 degrees for awhile now. It stays pretty constint on this temp. It will go up to 210 and the fan will come on, but will drop back down and stay there. This happens both while moving and sitting at stop lights.

Im thinking it is either the Thermosate or the ECT sensor...any ideas????

thanks for your input

 

I'd lean more toward gauge/sending unit/something electrical......don't see how it can actually run 150 even with no or stuck open t-stat unless your ambient temps are really low.......but wouldn't think it would reach 210 if they were.