General information about engine repair without removing it from the car (BMW 5 Series E28)

The four- and six-cylinder SOHC engines described in this manual are very similar in design. Where differences exist between them, they will be noted.

The means by which overhead camshafts are driven varies depending on engine type; the M10 and M30 engines use a timing chain, while the M20 and M40 engines use a timing belt.

Many major repairs can be done without removing the engine from the vehicle.

Before starting any work, clean the engine compartment and the outer surfaces of the engine using some kind of degreaser. This will significantly simplify the upcoming procedures and reduce the risk of introducing dirt into the engine.

Depending on the components you are going to work on, it may be useful to remove the hood to provide better access to the engine during repairs (if necessary, see Chapter Body). To avoid damage to painted surfaces, cover the car fenders with special covers, or, if you don't have them, blankets or bedspreads will do.

If oil, vacuum, exhaust or coolant leaks are detected and gaskets or seals need to be replaced, repairs can generally be made without removing the engine from the vehicle, as long as there is sufficient access to the intake manifold and exhaust manifold gaskets, oil pan, crankshaft and cylinder head seals.

With the engine installed on the vehicle, external components such as the intake manifold and exhaust manifold, oil pan, oil and water pumps, starter, alternator, distributor and fuel system components can be removed without hindrance for repair.



Removing the cylinder head does not require removing the engine. Maintenance of the camshaft, rocker arms and other valve train components is easiest with the cylinder head removed; these procedures are described in the relevant section. However, note that on the M40 engine, the camshaft can be removed without removing the engine, since it is held in place by the bearing caps.

In emergency situations, such as when the necessary equipment is not available, work such as repair or replacement of piston rings, pistons, connecting rods and connecting rod lower head bearings can be performed without removing the engine. However, this practice is not recommended, as it must be preceded by extensive preparatory work and thorough cleaning of all components involved.