All the items are within his estate, the rubber tube is in the closet on the first floor, the oil can is in the basement within a maze, and the last item is in the fountain outside of the mansion, piranhas inhabit the fountain so you will need the fish food and poison also found within the estate.
I have posted a link for you in the "Related Links"section below, that may be able to help you out.
this site will help
Go to youtube and search runescape ernest the chicken oil can.
for all the help i need with runescape i go on runehq.com
I have posted a link below in the "Related Links"section, I .
The top floor of Draynor Manor.
I think its in the kitchen on the ground floor
Poisoned Fish Food is needed for the quest 'Ernest the Chicken'. You will need Poison and Fish Food - both can be found inside Draynor Manor by searching the rooms. Use the Poison on the Fish Food to get Poisoned Fish Food.
For completing Ernest the Chicken, you get 4 Quest Points, 3000 gold pieces, 10 eggs and 300 feathers.
Seafood... is used to raise a players hp (health points). Unless your doing Ernest the Chicken quest then you have to put poison in it and kill the fish in the fountain outside Draynor Manor.
Check out Sals Realm of RS or the RS website for a guide.
Go to Runehq for quest help---they have the best, most detailed instructions for all of the RuneScape quests.
All of your quest questions can be answered at the following site. Check related link
The pressure gauge is found in the fountain which is somewhere around the manor, but not outside the manor gates. If you try to search the fountain ( right click, search ) you will notice that there is a school of vicious piranhas in there and it will cause you damage, but you will find some fish food and poison in the manor. Use the poison on the fish food, and it will become poison fish food. Feed it to the fishes and they will die and then you can get the gauge out safely.To see more information on the quest, Ernest the Chicken, go to the link below.