BMW M10 (M118) engine

M10 (M118) is a power unit from the Bavarians, which can be found under the hood of the BMW third series. With a working volume of 1.8 liters, engineers managed to achieve a maximum power of 90 or 98 horsepower, depending on the modification.

M10 (M118) engine specifications

Advantages

The engine uses a classic arrangement of cylinders – there are four of them, and they are installed in an in-line arrangement. This greatly simplifies the repair of the M118 engine, and such a procedure is relatively inexpensive. Spare parts can also be found quite easily, and inexpensively, as the power units were very popular in their time.

Engineers were able to provide a larger cylinder bore than the stroke of the pistons. This is a favorable decision from the designers at the time, since short-stroke power units are characterized by a larger cooling area and a smaller index of moving parts. This significantly extends the service life without the need to overhaul the motor.

Cast iron and aluminum were used as the main materials for the motor. This made it possible to combine minimum weight with maximum reliability, and the motor is very robust and provides good performance. At the same time, the cast iron cylinder block lends itself well to boring and repair.

The motor is characterized by a 30 degree tilt to the right side. This is done to reduce the forces acting negatively. Thanks to this feature, the motor is characterized by quite good driving characteristics in combination with a long service life, provided that quality fuel and original lubricants recommended by the manufacturers are used.

The location of the intake and exhaust manifolds has been very well thought out, so that they are located on two opposite sides. This has meant that virtually all engine parts that need to be removed during repairs are in accessible locations. The considerable simplification of the design reduces the cost of carrying out repairs and servicing the engine.

Disadvantages

Despite the fact that the BMW M118 engine is characterized by great success, it is not without its drawbacks. As a rule, motorists can encounter the following characteristic problems:

• The weakest point of this range of power units is that cracks appear in the cylinder block. As a rule, defects can be observed on the threaded connections designed for fixing the cylinder head and cooling jacket channels. Most often, cracks are caused by overheating of the power unit. The first sign of a crack is a decrease in the amount of antifreeze in the expansion tank, which is accompanied by emulsion in the lubricating fluid. Through the crack, some of the antifreeze can enter the crankcase of the power unit. This leads to the fact that the probability of overheating increases and the wear of rubbing parts increases. Almost all engines have this defect, so today it is extremely difficult to find a motor without a crack.
• The eccentric washer and rocker cam are characterized by a short service life. Therefore, almost all owners experience premature wear of these components.
• The cylinder head gasket is made of low-quality material, so it often burns out. This fault causes coolant to enter the combustion chamber.
• Increased oil consumption may occur at high mileage. The engine burns oil as a result of natural wear of the piston system and loss of properties of the piston rings. This is normal for Bavarian engines.

Despite the fact that the engine has certain faults, M118 engines are characterized by a fairly high reliability. They are characterized by ease of repair and maintenance, relative unpretentiousness to the quality of gasoline and lubricating fluid used. Despite the fact that these power units are quite old, on the roads of our country you can still meet cars, under the hood of which they are placed.

Technical specifications

The M118 is the first evolution of the M10 series of engines, which was derived from its predecessor, the M115. The engine displacement has been increased to 1,773 cubic centimeters by expanding the cylinder bore from 82 to 84 millimeters and changing the piston stroke from 71 to 80 millimeters. During the creation of the engine, the company’s engineers faced the task of keeping the minimum differences from the predecessor, as it was very cheap in production, as well as efficient.

This powertrain was almost permanently installed on the three versions of the 1800 sedan, which manufacturers referred to as the “New Class”. Several variants with different power outputs were offered to buyers.

From 1963 through 1968, the first 90 horsepower version was made and was installed under the hood of the 1800 sedan. It was fitted with a Solex 38 PDSI carburetor, giving it 90 horsepower at 5,250 rpm. Peak torque of 143 Nm was developed at 3,000 rpm.

From 1968 to 1975, a modification of the M118 engine was produced, which was characterized by a “short stroke”. The displacement of this version was 1766 cubic centimeters. The cylinder diameter remained the same, and the piston stroke was used the same as on the modification with a working volume of 1.6 liters. This negatively affected the technical characteristics of the power unit. Such motors can be found under the hood of BMW 1802 Touring 114, 1800-1802 Touring E6 and E12 518.

A 110 horsepower motor was also produced for the 1800 TI, featuring a dual Solex 40PHH carburetor. These design features allowed for up to 147 Nm of maximum torque at 4,000 rpm.

The engine, which was intended to be fitted to the 1800 TI/SA sport version, used a twin Weber 45DCOE carburetor in combination with a sport camshaft. The designers had to increase the bearing diameter to accommodate the higher-lift camshaft. This made it possible to obtain a maximum power of 130 horsepower at 6.1 thousand rpm. Torque of 153 Nm was achieved at 5,250 rpm.