BMW M30B33 engine

The BMW M30 is a direct fuel injection engine with a 6 SOHC system. A version of the gasoline engine that was produced from 1968 to 1992 with a production run of 22 years, it is the longest production conveyor belt that assembled a BMW engine and is used in many car models.

The first models to use the M30 engine were the E3. 2,500 and 2,800 sedans were produced. The original M30 models were produced with displacement from 2.5 to 3.0 liters (2,494-2,986 cc), with later versions having displacement up to 3.4 liters (3,430 cc) In keeping with the M10 inline-four engine from which it was developed, the M30 has an iron block, aluminum cylinder head and overhead valves with two per cylinder.

The engine was nicknamed the “Big Six” and “Older Six”, after the direct injection M20 engine was introduced in the late 1970s. The M30 was produced alongside the smaller M20 engine, until the introduction of the BMW M70 V12 engine in 1987.  The M30 was BMW’s most powerful and largest production engine.

After the introduction of the DOHC M50 engine in 1990, the M30 began to be phased out.

Ward’s rated the M30 as one of the “Top Engines of the 20th Century”

M30B33 engine specifications

Advantages

The m30 series engines are rightly regarded as the most reliable and durable engines available. All this indicates that BMW’s engine engineers maintain quality standards. The resource of more than 500,000 is justified by the high power, as this type of internal combustion engine is less loaded during moderate urban driving than its small-capacity counterparts. Drivers had complaints about the largest modification of the internal combustion engine with a volume of 3.5 liters. It turned out to be too powerful and quite problematic, compared to the younger modifications. It should be noted that the cylinder head is not equipped with two camshafts. At that time, the motorists decided to use only one.

There are also no hydrocompensators, so we recommend every 7-10 thousand kilometers to visit a service station in order to adjust the thermal clearances between the valves. In practice, this process should be done a little earlier than in the technical regulations. However, it does not make sense to talk about the average power of engines, because, for example, in the beginning of 1981 engines can get a compression ratio of 9 and output of 170 horsepower, and after minor modifications, which at that time came out more often than some videos on YouTube channels, after 4 months the engine could get a compression ratio of 9.5 and increase its power to 200 horsepower, which internal combustion engines can achieve at lower speeds.

The powertrain has changed several fuel supply systems.  We are talking about new carburetors and fuel injection control systems. As for the features of the M30 B33 engine, it is a bored version of the younger brother M30 B30. The larger displacement is achieved with new cylinders and increased piston stroke. But, despite these improvements, motorists decided to leave only one camshaft and not to install hydrocompensators. However, the M30B33 engine in garage conditions easily swung to the M30B35 version. Of course, for this purpose it is necessary to install new pistons, connecting rods. In some cases, replacement of the cylinder head was required. However, it was the most climbable engine in terms of tuning. Approximate power increase, thanks to artisanal modifications, was about 30-40 horsepower, compared to the power data, with which the engine came out of the assembly line.

Disadvantages

As for problems, despite their reliability and popular love on M30 engines, they do have some issues, although most of them are caused by owners’ hot rodding.

However, there were a few drawbacks from the factory. We will talk about them in this section.

The first thing to look for is cracks that occur in the cylinder block. The main vulnerable point is the bolt threads. Quite a serious defect, which in later versions was corrected by Bavaria Motors, but on earlier versions of this internal combustion engine, the error was quite common. The driver could notice a serious drop in the antifreeze level, and when changing the oil, emulsion could be seen. According to Bavaria Motors, the cause was due to grease that the technicians did not remove from the threaded wells.

In those years, in addition to robots, engines were assembled by humans. Therefore, inattention on the part of the assembly engineers was always present. The only way to solve this problem is to replace the cylinder block. You will have a very hard time finding a craftsman who will take on the task of fixing this problem. Once upon a time these internal combustion engines were replaced under warranty if the owner discovered this problem, but after almost 40 years of production, no warranty will cover this issue. And it seems to us that BMW’s own engine builders were surprised at the longevity of these internal combustion engines.

It is also necessary to pay attention to the constant overheating of M30 series engines. The problem was caused by defects in the cooling system, in particular the pump, thermostat, which were fastidious to dust and dirt that got into the system. At the beginning of the material we indicated a constant and comfortable for the engine operating temperature, so if you noticed that the arrow on the sensor rose more than 120-130 degrees, you need to urgently check the condition of the cooling system. If you do not pay attention to it, the cylinder head may rot.

Pay attention to the radiator. It may be contaminated with dust and dirt. Also pay attention to the condition of the pump and thermostat. In some cases, it is possible to form air plugs in the system, after replacing the antifreeze. These power units have not been produced for a long time, and their resource is almost rolled out. Therefore, with them there are bound to be problems associated with natural aging. Disruptions in the operation of the timing mechanism, valves (they wear out), crankshaft and bushings are not excluded.

M30 engines are cool and reliable units with a long service life. Cars based on them can “run” 500 thousand kilometers and even more. At the moment, the roads of Russia are full of cars with these internal combustion engines, which are still on the move. It is also worth highlighting the study of the design and problems of M30 engines, so replacement or repair of components is easy, but often there are problems with finding the necessary components. Therefore, repair of M30 engine may take more time.

Characteristics

Today we will talk about a gasoline engine that has a working volume of 3.2 liters and an average output of 190 horsepower. The M30B33 engine is installed on cars of Bavaria Motors 7 series. Let’s start with the technical characteristics:

The engine displacement is 3,210 cubic centimeters. The maximum power that this power unit can achieve is about 190-196 horsepower. Accordingly, the torque that this engine can achieve is 285 Newtons per meter, but in order to get the maximum figures, you need to accelerate the engine to 4350 rpm. This is a gasoline engine. The average fuel consumption in the mixed cycle is about 11.5 – 12.7 liters for every 100 km of mileage. As for the type of engine, it is an inline 6 cylinder power unit. The diameter of the cylinders is 89 millimeters.

Two valves per cylinder. Maximum power of 197 horsepower, which we stated above, the engine is capable of producing at 5500 rpm. There is no supercharger or turbo installed on the powertrain from the factory. The entire powertrain lineup has a pretty serious compression ratio of 9.3 units. The piston stroke is 86 mm.

The BMW m30 engine series was one of the most successful among the power units of the German concern. This is evidenced by almost 10 modifications, which are built on this power unit. Also the love of motorists for the reliability and maintainability of the power unit.

Each engine gets 6 cylinders and 2 valves on each cylinder. It was produced from 1908 to 1992. Despite the fact that the internal combustion engine is considered morally and technically obsolete as of early 2019, a lot of cars are powered by it to this day. It is also loved by the masters at the service station of motorists because of the huge operational resource, the realization of the declared power and the absence of serious technical problems, of course, with adequate operation and timely replacement of consumables.

All m30 engines were fitted with a cast iron cylinder head. In order to supply the engine with a fuel mixture, various carburetor and injector modifications were installed. The engine is quite susceptible to the quality of fuel, but from the factory it comes out with a recommendation of fuel with an octane number of 92.

The oil consumed by the engine should correspond to viscosity 5W30, 5W40, 10W40, 15W40. Total engine, for every 1000 kilometers, consumes about a liter of lubricant, provided adequate operation of the motor. The total volume is about 5.75 liters, which operates at a temperature of 90-95 degrees. Engine resource, in most cases – more than 500 thousand kilometers, which for modern internal combustion engines is considered almost unattainable indicator.

Mostly, these engines were installed on cars from 5 to 7 series BMW early years of production. More advanced internal combustion engines, which are equipped with turbines, smart fuel injection control systems, of course for their year of production, were installed on the car from 6 to 7 series in the early nineties of the last century.

The protagonist of our review had almost the largest volume in the entire line of engines. It is second only to the 200 cubic centimeters of the M30B35 model. The power unit is installed on BMW 635, 735, 535, L6, L7 cars from 1982 to 1988.

Modifications

M30B33 – version with a capacity of 3.23 liters, 185-220 hp and torque of 310 Nm at 4000 rpm. The unit was used in BMW 635, 735, 535, L6, L7 from 1982 to 1988.

Index B33 is a decoding of the working volume of the power unit. The Germans took the 3-liter engine as a basis, and significantly modified it. 33 series received a larger cylinder diameter and increased stroke of pistons. 92 and 86 mm, respectively. The cylinder head received one camshaft for 12 valves. Hydrocompensators were not provided. There were several versions of this engine.

Early copies had a compression ratio of 8 units and catalytic converters were installed. Useful power of such engines was 185 horsepower. Later versions received a compression ratio of 10 units, without catalysts and developed 218. Between them stood an engine with compression of 9 units and 211 horsepower. That is why it is difficult to say the exact value of power and torque in this powertrain.

This engine is installed on the following models:

BMW 7-Series (E23)