Toilets are attached to the floor using either two or four hold-down bolts. Over time, these bolts can corrode and allow the toilet bowl to rock which causes leaks. To repair this you must remove the old hold-down bolts and install news ones. Although installing the new bolts is straight forward, it can be a challenge to remove the old bolts, especially if the corrosion is extensive. However, with a little prep work the bolts will come out with no trouble.
Locate the silver, water shutoff valve on the wall behind the toilet and turn it clockwise until it will no longer turn. This shuts off the water supply to the toilet. Flush the toilet to remove all water from inside the tank.
Look at the bottom of the toilet bowl where it attaches to the floor. Grasp the white plastic caps on either side and pull up to remove them. Some caps twist counterclockwise to remove.
Spread old towels around the base of the toilet to protect the floor and apply 1 to 2 tsp of penetrating oil to each hold-down bolt on the base of the toilet. There is typically one bolt on either side of the toilet, but some toilets have two bolts on each side.
Allow the bolts to sit for at least one hour.
Place an adjustable wrench around the metal nut at the top of one of the hold-down bolts and close the wrench until it is tight. Rotate the handle of the wrench counterclockwise to remove the nut. Repeat to remove the nut on the remaining bolt.
Grasp the base of the toilet and lift it up from the floor. It helps to have someone help with this step. Move the toilet outside.
Place a rag inside the exposed sewer pipe to prevent smells from getting inside the home.
Turn each bolt-down screw counterclockwise until they come out of the metal toilet flange installed in the floor. You can do this by putting on work gloves and turning the bolts with your hand, or by using pliers. If your house is old, the bolts may be screwed into the floor instead of the flange.
Insert new hold-down bolts in the same location by twisting them down into the openings where the previous bolts were installed.
Remove the rag and bring the toilet back inside the home. Gently set the toilet down on the hole and thread the bolts through the holes in the bottom of the toilet.
Insert new metal nuts on top of the bolts and turn them clockwise with the wrench until they are secure. Do not over tighten them since this will crack the toilet bowl.
Press or screw the white plastic bolt caps back on top of the bolts. Turn the water shut off valve counterclockwise to supply water back to the toilet.