BMW 5 Series E39

since 1996-2001 release

Repair and operation of the car

Procedures of repair of the engine

General information

M52 engine (520i, 523i, 528i)

M51 engine (525tds)

On the BMW cars of the 5th series engines of three types are installed: 6-cylinder petrol, 6-cylinder turbodiesel and V8 engine. V8 engines (volume of 3.5 and 4.0 l) is considered only in the section "Maintenance".

The power unit is installed along the car and is taken out only upward by the crane.

The 6-cylinder petrol engine has the designation M52. Its head and the block of cylinders are cast from aluminum alloy. Unlike traditionally applied cast iron aluminum alloy has higher heat conductivity and smaller weight. It promotes the best cooling and lower fuel consumption. The head of cylinders 4-valvate, has the adjustable camshaft of inlet valves (designation of BMW - VANOS).

On model 525tds the 6-cylinder turbodiesel of M51 of 2.5 l is established. The block of cylinders is cast from cast iron, a head of cylinders from light alloy.

At the increased wear and existence of zadir of walls of cylinders they can be honingovat. After that it is necessary to use repair pistons.

The head of cylinders at all engines has a so-called cross purge. It means that fuel mix comes to working cylinders on the one hand, and the fulfilled gases come out with another. It promotes more bystry gas exchange. In a head of cylinders camshafts are located. The diesel engine has only one camshaft. 4-valvate petrol engines have two camshafts. One sets in motion inlet valves, another final. The drive of camshafts is carried out through a roller chain. Valves are set in motion through hydropushers. Need of adjustment of gaps for valves in the course of maintenance is absent.

6-cylinder petrol engines have the adjustable drive of gas distribution. At the same time the camshaft of inlet valves depending on engine speed by means of an adjusting element is turned rather driving asterisk in such a way that the optimum moment of opening of valves is provided. Adjustment is carried out by the control unit opening and closing the oil valve of pressure.

Supply of oil in the lubrication system is carried out by the oil pump which at the 6-cylinder petrol engine settles down in front in the pallet of a case and is set in motion from a bent shaft. At the diesel engine the oil pump is in a distribution drive case cover on the end of a bent shaft and is set in motion from the tooth gearing. Oil is sucked in from the pallet of a case and through openings and pipelines moves to bearings of cranked and distributive shaft, and also to the working surfaces of cylinders.

The pump of cooling liquid is located in a forward part of the block of cylinders. The pump shaft at achievement of the corresponding temperature sets in motion the cooling fan via the viscous coupling. The drive of the pump is carried out through maple a belt which at the same time set the generator in motion. It must be kept in mind that the cooling system is all the year round filled with antifreeze mix, a security measure from corrosion and water with the low content of lime.

Preparation of air-petrol mix is carried out by system of injection and electronic ignition thanks to what stable value of emission of the fulfilled gases is provided. The system of ignition with coils of ignition has no mobile elements that excludes wear of its elements. At the diesel engine distribution of fuel on cylinders is carried out by the DDE system (digital diesel electronics).

Petrol engines are calculated for work on AI-95 gasoline, however thanks to existence of detonation regulation also other grades of fuel can be applied. If AI-98 gasoline is applied, then under normal conditions operation fuel consumption is cut and engine capacity increases. At use of AI-91 gasoline engine capacity decreases and fuel consumption increases.