Most basic repairs can be performed without removing the engine from the vehicle.
Before starting any work, it is recommended to flush the engine compartment and the engine with a jet of water. A clean engine is easier to work with because contamination of the engine's internal components can be prevented. To expand the working space and not damage the paintwork, remove the hood and mudguards. If traces of oil or coolant leaks are observed, indicating the need to replace gaskets, then all work is usually carried out without removing the engine. Without removal, you can replace the oil pan gasket, cylinder head gasket, intake and exhaust manifold gaskets, front and rear covers and the crankshaft oil seal.
Without removing the engine, you can remove the water pump, starter, alternator, ignition distributor, intake and exhaust manifolds, fuel pump and carburetor.
Since the cylinder head can also be removed without removing the engine, the valve train can also be repaired. Without removal, work such as replacing or checking the condition of the toothed belt, timing belt pulleys, oil pump and front cover seal can be performed.
In extreme cases, when the necessary equipment is not available, piston rings, pistons, connecting rods and connecting rod bearings can be replaced without removing the engine, and cylinders can be honed. However, it is not recommended to perform these works without removing the engine, since it is necessary to clean the related parts and perform preparatory measures.