Strange ticking rattling on 4.3 V6

[Kubaat3lover]

Hello boating friends,
Finally on the water but after 1st start I’ve noticed strange ticking / rattling only @ idle.
Any ideas will be appreciated …

 

[Scott06]

Exhaust flappers. the rubber wears off them and they make noise. When you accelerate they stay open

 

[stresspoint]

year of motor ? , possibly a hydraulic lifter not quite up to par. if non adjustable it will need replacing or just live with it.
if however you have an adjustable lifter motor you may get away with a valve lash adjustment.

 

[Kubaat3lover]

2005 approx 400hrs