Before head gasket replacement have you checked these
Intake Manifold Gaskets May Leak Coolant or Engine Oil
engine or leak. In some cases, an internal coolant leak may occur causing coolant to mix with the engine oil. Our technicians tell us that operating the engine with a coolant/oil mix can result in internal engine damage. Replacing the intake manifold gasket should correct these leaks.
Leaking Water Pump May Cause Coolant Loss and Overheating
A coolant leak may develop from the . The may overheat as a result of the coolant loss. A leaking water pump should be replaced.
step 1. undo negative battery cable or completely remove battery and tray.
step 2. remove air cleaner and associated piping if it is in the way to allow access to head, drain cooling system and remove upper radiator hose.
step 3. remove top portion of exhaust manifold.
step 4. remove intake manifold and fuel injection rail as necessary
step 5. remove spark wires and valve cover.
step 6. remove drive belts and top timing cover before removing timing belt find all alignment marks and paint to improve your visibility and aid in reassembly if no marks are present remove spark plug # 1 and rotate until piston is at tdc and check timing mark on crankshaft that it is on 0 then paint the belt and cams anything that has teeth that the timing belt rides on make a mark to aid in reassembly even if you are replacing t-belt at least you can compare to new belt and transfer marks, release tension on t-belt tensioner and remove t-belt.
step 7. remove head bolts start loosening at inside and work outwards reemove head bolts and pay attention to sizing and placement.
carefully check for anything that is still attached to head and if free tap head with rubber or dead blow hammer to free from block and lift straight up so as not to ruin or bend any of the alignment pegs.
step 8. remove head gasket material with non-scratching tools or scrapers or buff pads made for that job. making note of where it was blown.
step 9. decide if you should send head to machine shop to have mating surface made flat again and also to have valves and related parts inspected or replaced. usually about $300-$400
step 10. inspect block remove all gasket material look for pitting or scarring also use straight edge to determine if it is straight or if it needs to be resurfaced by a machine shop.
step 11. install new headgasket and check fit. If all is good reassemble in reverse order of removal and I always like to replace crank seal ,cam seal, water pump, t-belt and tensioner also thermostat, drivebelts, spark plugs, cap, rotor, wires, pcv valve, intake manifold ,exhaust manifold gaskets.
this is just a broad overview hope it helps you will have to get haynes manual or similar for head torque values and what not