Engines BMW M50B25, M50B25TU

Buying a BMW car for most consumers is a guarantee of purchasing a quality car that will last much longer than its competitors.

The secret of the reliability of cars is in the control of their production at all stages - from the manufacture of parts to their assembly into units and assemblies. Today, not only branded cars of the company are popular, but also manufactured engines - which are often installed on cars of classmates instead of regular internal combustion engines.

A bit of history

In the early 90s, BMW pleased car owners with the release of a new M50B25 engine, which replaced the outdated M 20 unit at that time. Compared to its predecessor, a high power factor was achieved - the cylinder-piston group was modernized, which used lightweight and durable parts, made by special technology to lighten the weight.

The new version was distinguished by stable operation - the gas distribution mechanism included upgraded valves, which were much lighter and had a longer resource than on the M 25. Their number per cylinder was 4 instead of 2, as it was before. The intake manifold was twice lighter - its channels had ideal aerodynamics, providing better air supply to the combustion chambers.

The design of the cylinder head has changed - beds were machined in it for two camshafts that served 24 valves. Motorists were pleased with the presence of hydraulic lifters - now there was no need to adjust the gaps, it was enough just to monitor the oil level. Instead of a timing belt, a chain was installed on this ICE for the first time, which was regulated by a hydraulic tensioner and required replacement only after passing 250 thousand kilometers.

The manufacturer upgraded the ignition system - individual coils appeared, the operation of which was regulated by the Bosch Motronic 3.1 engine management system.

Thanks to all the innovations, the motor had almost ideal power indicators of that time, had low fuel consumption, a high environmental class and was less demanding on maintenance.

In 1992, the engine underwent another update and was released under the name M50B25TU. The new version was finalized and received a new Vanos gas distribution system, modern connecting rods and pistons were installed, as well as a Bosch Motronic 3.3.1 control system.

BMW E34 M50B25TU

The motor was produced for 6 years, two versions were produced - 2 and 2,5 liters. At the beginning of production, it was installed on cars of the E 34 series, then on the E 36.

Technical specifications

Many motorists have difficulty finding a plate where the series and engine number are stamped - since its location is different for different models. On the M50V25 unit, it is located on the front surface of the block, near the 4th cylinder.

Now let's analyze the characteristics of the motor - the main ones are shown in the table below:

Cylinder block material	cast iron
Supply system	injector
A type	in-line
Number of cylinders	6
Valves per cylinder	4
The piston stroke, mm	75
Cylinder diameter, mm	84
Compression ratio	10.0
10.5 (UT)
Engine displacement, cc	2494
Engine power, hp / rpm	192/5900
192/5900(TU)
Torque, Nm / rpm	245/4700
245/4200(TU)
Fuel	95
Environmental standards	Euro 1
Engine weight, kg	~ 198
Fuel consumption, l/100 km (for E36 325i)
- town	11.5
- track	6.8
- funny.	8.7
Oil consumption, gr. / 1000 km	to 1000
Engine oil	5W-30
5W-40
10W-40
15W-40
How much oil is in the engine, l	5.75
Oil change is carried out, km	7000-10000
Engine operating temperature, deg.	~ 90
Engine resource, thousand km
- according to the plant	400+
- on practice	400+

Overview of the main design features of the motor:

• M50V25 is an in-line six-cylinder engine with a volume of 2494 cm³. Its design is represented by a cast-iron block, in which six cylinders with a diameter of 84 mm are located in one row. The motor has good torque (245 Nm / rpm) and power (192 hp), giving you complete control over the car both in traffic jams and on a country road. It is important to note that appetites for these parameters are quite moderate - fuel consumption is from 8,7 to 11,5 l / 100 km, depending on the driving mode.
• The cooling system is liquid, circulation is provided by a pump driven by a crankshaft pulley. The thermostat regulates the flow of antifreeze in a large or small circle, providing a full temperature regime for the engine.
• The lubrication system provides oil supply to the main rubbing units using pressure pumped by a gear-type pump, which is located in the sump. To improve the operation of the unit, as well as to prevent clogging of the oil channels, a special filter is installed in the system;
• The crank mechanism is represented by six forged lightweight connecting rods and pistons, the stroke of the latter is 75 mm. Under their action, the crankshaft rotates, transmitting torque to the vehicle's transmission. The compression ratio for the classic version of the internal combustion engine is 10,0, for the M50V25TU - 10,5.
• The ignition system includes one coil for each cylinder, the operation of which is controlled by the Motronic 3.1 engine management system. This design ensures uninterrupted ignition of the working mixture;
• The gas distribution mechanism is represented by a timing chain, a hydraulic tensioner, two camshafts and valves with their guides - each cylinder has 2 intake and two exhaust valves. When the crankshaft rotates, the chain ensures the synchronous movement of the camshafts, which open the valves one by one.

Features of the M50B25TU engine

This series is a more advanced version - changes were introduced 2 years after the release of the main engine. The goal for the engineers was to reduce noise, increase efficiency and reduce fuel consumption. The main modifications of the M50V25TU are:

• The use of the new control system DME 3.3.1 and the controller Siemens MS 40.1, which allow optimal control over the main processes of the engine. This made it possible to increase power and reduce fuel consumption;
• Change in the design of the crank mechanism - the new version uses more advanced parts that are durable, light and have an increased service life. The compression ratio has increased, new counterweights have appeared on the crankshaft to reduce axial runout and vibration;
• The timing was modernized - the new series uses lighter and stronger valve lifters. The return of the valve to its original position is carried out using one spring;
• The motor received a different model of the idle speed sensor, which maintains the optimal mode of operation of the internal combustion engine at idle, according to the updated parameters.

Another distinctive feature of the engine is the presence of the Vanos system, which regulates the operation of the gas distribution mechanism depending on the load, coolant temperature and other characteristics.

Vanos - design features, work

This system changes the angle of rotation of the intake shaft, providing the optimal mode of opening the intake valves at high engine speeds. As a result, power increases, fuel consumption decreases, ventilation of the combustion chamber increases, the engine receives the required amount of combustible mixture in this mode of operation.

Vanos system design:

• Hydraulic device for changing the position of the intake camshaft;
• Electromagnetic switch;
• Oil line with valve;
• Electronic controller.

The operation of this system is simple and effective - the control sensor analyzes the parameters of the engine and, if necessary, sends signals to the electromagnetic switch. The latter is connected to a valve that shuts off the oil pressure. If necessary, the valve opens, acts on a hydraulic device that changes the position of the camshaft and the degree of opening of the valves.

Motor reliability

BMW engines are among the most reliable, and our M50B25 is no exception. The main design features that increase the service life of the power unit are:

• Using a chain instead of a belt - replacement is required much less often, and reliability is higher;
• Installation of hydraulic lifters - no scheduled adjustment required;
• The use of new engine control systems (DME 3.3.1, Siemens MS 40.1, Vanos) - increases the resource of spare parts, as it optimizes the operation of the internal combustion engine;
• Many parts are made of high-strength alloys.

The resource that the manufacturer sets is 400 thousand kilometers. But according to the reviews of motorists - subject to the operating mode and timely oil change, this figure can be safely multiplied by 1,5 times.

Basic problems and their elimination

There are few sores on the motor, here are the most common of them:

• Overheating - this malfunction is best not to be trifled with, as it rarely goes away without consequences. It is recommended to check the condition of the cooling system, the presence of antifreeze and the likelihood of air pockets;
• Troit engine - most often the problem is in the ignition coils;
• Uneven speed - in most cases, the idle speed controller is to blame. Clean it with a special fluid and a pump. If the problem persists - the cause may be a throttle sensor or a lambda probe, it is also recommended to clean the throttle and check the integrity of the intake manifold;
• Reduced power is usually the cause of the failure of the Vanos system. The problem is eliminated by replacing it, for this it is advisable to contact a car service.

These are the main weak points of our engine. Often there are classic malfunctions in the form of oil leaks, failure of various sensors that require replacement.

What kind of oil to pour?

The choice of oil is always a very difficult task for a car enthusiast. In the modern market, the probability of running into a fake is very high, and you can kill the heart of your beast after one replacement. That is why experts recommend not to purchase fuels and lubricants in dubious stores or if there is a suspiciously cheap discount.

The following oils are suitable for our engine series:

• 5W-30;
• 5W-40;
• 10W-40;
• 15W-40.

It is important to remember that according to the manual - oil consumption of 1 liter per 1000 km is considered normal, but according to reviews, this figure is too high. It is necessary to change the oil and filter every 7-10 thousand km.

List of cars on which the M50V25 was installed

• BMW 325i E36;
• BMW 525i E34.