Tie rod persistently becoming slack . Reasons

• Uneven tightening procedure
• Uneven tightening torque
• Over tightening
• Overloading of main engine
• Threads - not machined properly or cleaned
• VIT not adjusted -Pmax too high
• Improper power balance
• Rough weather- fluctuation
• Scavenge fire
• Loose foundation bolts
• Loose pinching screw
• Engine is new - no proper matching and bedding is done
• External vibration - Hull fouling , propellor tip clearance is less