Originally Posted by BUP

Replacing seals - do you mean exhaust hose or exhaust tubes ? Do you have stock Mercruiser exhaust and risers ? if yes to both questions, I most likely know your problem(s). Before explaining all of this make sure you do not have any exhaust/ water outlet restrictions - even with the exhaust manifolds & risers. Make sure your water ports are free and clear. There is more but really need to know what you have.

If you mean your exhaust hose or exhaust tubes look on the inside to make sure you are not blistering them from heat in return tears them open from the inside out..