My analysis is that problem is with the temp guage plug or the guage dial in dash board. There are only two variables here heat and resistance (or u may call it impedence), lets enlist all possible issues :
[U]Heat
[/U]- temp plug (its actual name is temp sending unit) is not insulated from body. If i'm not wrong then a rubber seal is there which insulates it from body
- temp sending unit is faulty (i doubt that)
- You are installing in correct pattern sending unit, please note that mehran and khyber sending units are almost identical but they give incorrect reading if used in wrong vehicle
impedence
Incorrect impedence of sending unit
Incorrect impedence of dial guage
Generally both these units are disposable type (meaning cannot be repaired)