I just replaced the oil pan gasket on my 2002 GT. It was a pain to do and I imagine it's the same way on yours. The Hanes repair manual leaves a lot out and makes it seem simple when it's not. The $40 part cost beats the $500 mechanic cost so it is worth it.
Once engine has cooled down, jack the car up and support it on jack stands. Remove the passenger side wheel.
Loosen the oil plug and drain the oil from the oil pan. (M15 bolt)
Remove the old oil filter and drain.
Remove the drive-plate inspection cover located on the driver’s side of the oil pan. There are two M10 bolts holding it in.
Removing the passenger side engine mount
Support the engine with a hydraulic jack and lift 2-3 inches. The lower passenger side engine mount is a U-shaped part located on the passenger side of the oil pan. The oil pan cannot be removed without removing this mount. There are five M15 aluminum bolts and two M15 aluminum nuts holding the mount in place. Once the weight of the engine is removed, the bolts will be easier to loosen. There are three bolts on the rear side of the mount and two on the front side. The two M15 nuts are located directly behind the oil filter. Once all seven nuts and bolts are removed, loosen the boot supporting the engine mount from underneath. There are two M15 bolts holding it in place. These do not need to be removed, only loosened to allow space to remove the engine mount. Remove the engine mount.
Removing the oil pan
The oil pan is held in by 3/8” hex bolts with ¼”-20 threads. Carefully loosen and remove each bolt and be sure to keep track of them and not lose them. Clean each bolt with carburetor cleaner to remove debris and oil. The oil pan should fall down but if it does not, tap with a soft hammer. The oil pan will catch on the lip of the transmission pan. You will need to pry the pan over the lip with a crowbar or screw driver. Be very careful not to damage the lip of the oil pan. Once loose, clean the oil pan lip with a solvent to remove oil.
Removing the old oil pan gasket
The old gasket likely was glued on, so it will remain in place. Before removing, loosen the two bolts (but don’t remove) holding the oil sump pump (M8). This will make it easier to remove the old gasket. With the sump pump now loose, tap loose the old gasket. Be sure not to damage the lip where the gasket seals to engine block or the new one will not seal properly. Maneuver the old gasket around the sump pump and remove.
Installing the new gasket
Clean the lip where the gasket seals on the engine block with carburetor cleaner or some solvent. Remove any old gasket sealant with a fingernail as to not damage the surface. Once cleaned, place the new gasket around the sump pump and tighten the two sump pump bolts to hold the new gasket in place.
Re-installing the oil pan
Place the oil pan back in place by again prying it around the transmission pan lip carefully. Once in place, begin replacing the bolts. Start them by hand and then ratchet them back into place following a criss-cross pattern. Do not over-torque or the bolts will break and will have to be removed with an easy out. The bolts are designed to break off before they strip out the threads on the engine block so be careful. Snug tight and then a quarter turn is enough. It is recommended to us a torque wrench for this but if you don’t have one, use common sense.
Re-installing the lower engine mount
With the oil pan back in place, place the mount back into place. Raise or lower the engine to align the five M15 bolt holes that hold in the mount. When holes are aligned, replace the bolts and tighten. Tighten the two M15 nuts holding the mount to the boot and then tighten the boot to the frame. Lower the jack supporting the engine and remove.
Replace the drive inspection plate and replace the oil pan plug. Install the new oil filter. Install 4.5 quarts of oil and check the dipstick to verify full.
Turn on the engine and let it get up to operating temperature and inspect the oil pan for leaks. Once the inspection is passed, replace the wheel and lower the car off of the jacks.
