Preparatory work and list of repair procedures that can be performed without removing the engine from the vehicle

Clean the engine compartment and the exterior surfaces of the engine using one of a wide range of special solvents. This treatment prevents dirt from entering the engine.

If necessary, depending on the nature of the work, the hood may be removed to provide free access to the components being serviced (see Body Chapter). Cover the fenders with protective covers or simply old blankets to prevent accidental damage to the paint finish.

If there is suspicion of vacuum loss or leaks of oil, coolant, exhaust gas, etc., indicating the need to replace the relevant gaskets or seals, almost any of the listed procedures can be performed without removing the engine from the vehicle (in situ). This applies to replacement of the intake manifold and exhaust manifold gaskets, oil pan gasket, cylinder head gasket, and both crankshaft seals.

Removal, repair and installation of external components and attached assemblies such as the intake manifold, exhaust manifold, oil pan, water pump, starter motor, alternator, ignition distributor and fuel system components can also be carried out in situ.

Since the cylinder head can be removed from the engine without first removing the engine from the vehicle, repair of the camshaft and valve train can also be performed directly on the vehicle. In addition, the timing belt and timing drive sprockets are normally replaced in situ.

In an emergency, without removing the engine, it is also permitted to repair or replace piston rings, pistons, connecting rods and connecting rod bearings. However, this option should not be used routinely, because of the difficulties involved in maintaining cleanliness and performing the required preparatory procedures.