awkward job,but can be done no need to take engine out unless you like work, hammer and punch or scew driver drive the punch or screw driver in to the center of the core plug and prise it out, scrape out all the old sealent out making sure there are no bits of rust inside the recess put some new sealent in recess place the new core plug in situ and tap back in the hole using a drift or short piece of a broom handle,