Repair operations possible with the engine in the vehicle
Many major repair operations can be accomplished without removing the engine from the vehicle.
Clean the engine compartment and the exterior of the engine with some type of degreaser before any work is done. It will make the job easier and help keep dirt out of the internal areas of the engine.
Depending on the components involved, it may be helpful to remove the hood to improve access to the engine as repairs are performed (see Body, if necessary).
Cover the fenders to prevent damage to the paint. Special pads are available, but an old bedspread or blanket will also work.
If vacuum, exhaust, oil or coolant leaks develop, indicating a need for gasket or seal replacement, the repairs can generally be made with the engine in the vehicle. The intake and exhaust manifold gaskets, oil pan gasket, crankshaft oil seals and cylinder head gaskets are all accessible with the engine in place.
Exterior engine components, such as the intake and exhaust manifolds, the oil pan, the oil pump, the water pump (see Cooling, heating and air conditioning systems), the starter motor, the alternator and the fuel system components can be removed for repair with the engine in place.
Since the cylinder heads can be removed without pulling the engine, valve component servicing can also be accomplished with the engine in the vehicle. Replacement of the camshafts, timing chains and sprockets are also possible with the engine in the vehicle.