@waqashussin,check the condition of thermostat valve.it is most often found under the housing.some newer modles locate thermostats in a housing sealed by a cover that looks just like a radiator cap.TO test the thermostat,hang a thermometer in a pan of water and place it on the stove.Suspend the thermostat in the water,now heat the water,noting the temperature at which thermostat valve begins to open.If the thermostate does not open at the temperature stamped on its body,it is defective and must be replaced.
Check the condition of water hoses,look for cracking,swelling and oil or grease damage to hoses.Pay particular attention to the area just behind the clamp,some times the clamp will dig its way into hose pipe causing for leakage.
Check the belt tension by applying a little push with ur thumb in the centre of the belt,if u can deflect it more than 15 to 20 mm,it means belt is too loose and u would need to tighten it.Also keep in mind that the belt should not be over tightened this would cause a bearing failure and resultant damage to the driven part.