The BMW M42 is a straight-4 DOHC piston engine produced from 1989 to 1996. It was produced alongside the M40 straight-4 engine, as the higher performance engine. It was also used in North American versions of the E36 318i instead of the M40. The M42 was replaced by the M44, which was introduced in 1996.

Compared with the M40, the M42 features a DOHC valvetrain, a timing chain, hydraulic valve lifters and an increased 10:1 compression ratio. Later versions of the M42 also feature a dual length intake manifold (called "DISA").

The M42 was used as the basis for the S42 racing engine, which powered the BMW 320i in the German Super Tourenwagen Cup.

Design

Following BMW's typical construction techniques at the time, the motor incorporates a cast-iron block and aluminium head. Weight-saving measures include aluminium chain cases, oil sump, motor mount arms, accessory mounts and a cartridge-style oil filter housing. Closely related to the SOHC M40, the M42's DOHC 16 valve head and chain-driven cams provided increased power in comparison to the M40.

The M42 also incorporates other performance features such as a forged steel crankshaft and welded tubular stainless steel exhaust manifold instead of the more typical cast-iron items. BMW also fitted hydraulic motor mounts to decrease the inline four's inherent noise, vibration and harshness (NVH) compared to the smoother inline sixes already in production at that time.

When installed in the BMW E30, a two-piece oil pan with a removable front sump was fitted to the M42. In this two-piece arrangement, the upper oil pan casting incorporates the oil pump's supply passage, and is sealed to the crankcase oil filter housing with a paper gasket. This can cause problems, because thermal cycles and engine vibration tend to loosen the six 10mm upper pan mounting bolts inside the motor.

All versions featured a low-maintenance timing chain with a self-adjusting hydraulic chain tensioner and hydraulic valve tappets. The M42 also incorporates the Bosch Motronic M1.7 DME, eliminating a distributor in favor of fully electronic ignition timing.The DME was configured to fire four individual remotely mounted coils. Furthermore, in markets that required emissions controls, the DME also incorporates an upstream O2 sensor and three-way catalyst.

Running changes

The earliest versions of the M42 developed problems with the camshaft chain drive. The hydraulic tensioner,chain guides, idler wheel and rear lower chain case have all been updated to resolve mechanical wear problems experienced in the early versions of the M42. Since the updated cam chain tensioner is shared with the M44, people commonly refer to the revised tensioner as a "M44 tensioner".

In the final versions of the M42, BMW engineered a dual length intake manifold (called "DISA" by BMW)

Recalls

Early models of the M42 experienced failures of a profile gasket sealing the lower cam chain case to the underside of the cylinder head. This gasket seals the primary coolant passage within the timing chain case. A significant failure would thus discharge pressurized steam and hot coolant into the timing chain case. In many cases this coolant rapidly contaminates the motor oil in the sump, causing main bearing failure. BMW updated the profile gasket material and instituted a program to repair motors under warranty. In extreme cases, the aluminum mating surfaces in the head and chain case would corrode.

Models

M42B18

The M42B18 has a displacement of 1,796 cc, which is achieved through a bore of 84 mm and a stroke of 81 mm. The engine uses Bosch Motronic 1.7 fuel injection. Versions equipped with a catalytic converter produce 100 kW and 172 Nm. and meets with Euro2 norms.

Applications:

• 1989-1991 E30 318i (only North American models)
• 1989–1991 E30 318iS
• 1992–1996 E36 318i/318ti (only North American and South African models)
• 1992–1996 E36 318iS
• 1996 Z3

S42B20

A racing version of the M42 Engine, called the S42 was used in BMW's 320 4-door touring car, participating in the German racing series called STW (Super Tourenwagen Cup). It differed by having individual throttle bodies (ITB) for each cylinder and its capacity was enlarged to 1999 cc. It had eight fuel injectors instead of the standard four. Valve cover and airbox were entirely made of carbon fiber. Lubrication was provided by a dry sump system. Compression ratio was increased and a lightweight head installed.

Horsepower evolution steps of the S42 Engine:

In its final evolution, this engine develops 158 HP/l.

Production period:	1987-1994
Manufacturer:	BMW
How it works:	Otto
Engine Type:	R4
Valve control:	OHC
displacement:	1596-1795 cm 3
Fuel supply:	manifold injection
Engine charging:	none
Power:	73-85 kW
Previous model:	M10
Successor:	M43

The BMW M40 is an inline-four SOHC piston engine which replaced the M10 and was produced from 1987–1995.

The M40 is a water-cooled four-cylinder gasoline engine with a crankcase made of gray cast iron . The cylinder spacing is 91 mm. 

The engine has a cast crankshaft with eight counterweights.  The cross-flow cylinder head consists of chill casting. The overhead, belt driven five bearings camshaft of the engine is made of chilled cast iron manufactured and operated per cylinder via drag levers each an inclined by 14 ° inlet and an outlet; the intake valve discs are 42 mm larger than the 36 mm exhaust valves. They have a hydraulic valve clearance compensation. Furthermore, the camshaft of the BMW M40, although made of shell-molded, is susceptible to "shrinkage", which is caused by the direct sliding of the drag levers on the camshaft. Mixture preparation is carried out by means of intake manifold injection ,  which is controlled by the Bosch Motronic M 1.3.  It contains the Lamba probe for the regulated three-way catalyst . Note: The four-valve version is the BMW M42 . 

Displacement ranges from 1.6 L (1596 cc; 97.4 cu in) to 1.8 L(1796 cc; 109.6 cu in). It began to be replaced by the M43 SOHC engine in 1991, however from 1989 the M40 was produced alongside the higher performance M42 DOHC four-cylinder engine.

Compared with its M10 predecessor, the M40 uses a belt-driven camshaft, and hydraulic tappets. Like the M10, the M40 uses an iron block and an aluminium head.

Fuel injection for the E30 versions is Bosch Motronic 1.3, and the E36 versions use Motronic 1.7.

M40B16

The M40B16 is a 1.6 L (1,596 cc) version of the M40, which has a bore of 84 mm (3.3 in) and a stroke of 72 mm (2.8 in). It produces 102 hp (76 kW) and 105 lb·ft (142 N·m) of torque. The E30 version uses Bosch Motronic 1.3 fuel injection, while the E36 version uses Motronic 1.7.

Applications:

• 1988–1994 E30 316i
• 1990–1994 E36 316i
• 1992–1993 Bertone Freeclimber 2

M40B18

The M40B18 is a 1.8 L (1,796 cc) version of the M40, which has a bore of 84 mm (3.3 in) and a stroke of 81 mm (3.2 in). It produces 113 hp (84 kW) and 120 lb·ft (160 N·m) of torque. Like the M40B16, the fuel injection system is Bosch Motronic 1.3 for the E30 versions and Motronic 1.7 for the E36.

Applications:

• 1987–1994 E30 318i
• 1988–1994 E34 518i
• 1992–1993 E36 318i

The BMW M30 is a straight-6 SOHC piston engine which was produced from 1968 to 1994. The first model to use the 2494 cc version of the M30 was the E3 2500. Over its 28-year lifespan, the M30 was used in many BMW models. Although there was no direct replacement for the M30 engine, effectively the v8 M60 and straight-6 M50 (smaller capacity than the M30, but with DOHC) took over from the M30.

Initially, the engine code was "M06", before it was renamed the M30 in the mid 1980s. The engine has been given the nicknames of 'Big Six' and 'Senior Six', following the introduction of the smaller BMW M20 straight-6 in the late 1970s.

Development

The M30 was originally developed in the late 1960s, loosely based on the straight-four BMW M10 engine first used in the 'Neue Klasse' BMW 1500. Several features, including a profile lowering 30-degree slant to the right, a crossflow head (a gas flow head in later desgins) and a chain-driven single overhead cam with rocker arm valve actuation are common between the M10 and the M30.Further similarities include a cast-iron block with an aluminium head and a forged crankshaft. The first two engines introduced were the 2.8 and the 2.5 litre option, both short-stroke engines sharing a common bore.

The engine block with a cylinder clearance of 100 mm is made of gray cast iron , the crankshaft is mounted seven times. 

The cross-flow cylinder head is made of light metal. The by a timing chain , in many variants, a duplex chain, driven overhead camshaft operated two valves per cylinder . By varying the bore and the stroke , engines with 2.5; 2.8; 3.0; 3.2; 3.3 and 3.5 liters capacity.

For mixture formation were carburetor or intake manifold injection ,1979 for the 3.2 and 3.5 l versions of the digital engine electronics, since 1986 in conjunction with the catalyst , to the application. End of the 70s, in the 5 series from the E28 1981, vertically arranged suction systems were used for weight reasons,  . Images injection versions. When the engine was introduced in 1968 new for a soft and also favorable in terms of exhaust combustion as a three-ball swirl tank with volume concentration around the spark plug designed combustion chamber. This also protects the bearings.  Also versions with turbocharger were developed; in series came in the 1980s, the 745i .

As a tuning base, the M30 engine was used among others the companies Alpina , Hartge and Schnitzer .

The M30 was finally replaced by the equipped with four-valve technology BMW M50 (six-cylinder in-line engine, 24V). For the BMW E32 was parallel to the eight-cylinder - V-engine BMW M60 (32V) continue to be offered the M30B30.

Turbocharging

The M30 was the basis for the turbocharged M102 and M106 engines.

The Alpina B10 Biturbo used a modified version of the M30, with two turbochargers and forged pistons. Producing 265 kW/360 hp at 6000 rpm and 520Nm/384 lb-ft at 4000 rpm, the engine made this car the fastest sedan in the world. The final 50 M30 blocks were shipped to Alpina for use in the final 50 B10 Biturbos.

Motorsport

The M30 powered a series of BMW 6-cylinder E9 and BMW E24 coupes to European Touring Car Championship (ETCC) throughout the 1970s and into the middle 1980s, even though a more powerful DOHC 24-valve head had been developed for high-performance motorsports and street use.

The BMW M88 high-performance engine is based on the M30 block.

M90

The M90 engine, used in several models from 1979-1982, combines the block from the motorsports BMW M88 engine with the M30's SOHC cylinder head.

Data 

The weight of the engines is between 192 kg in the 2.5 l variant for the BMW 525 from 1976, 199.5 kg for the engines in 3.0s / si, up to 212 kg of the M30B35. The turbo versions weigh 225 kg. 

2.5 litre

The first model to use the 2494 cc version of the M30 was the E3 2500 in 1968. Unless otherwise noted, these engines use a carburetor.

Applications:

• 1968-1977 E3 2500
• 1974-1975 E9 2.5 CS
• 1973–1976 E12 525 (107 kW)
• 1975-1979 E23 725 (110 kW)
• 1976–1981 E12 525 (110 kW)
• 1981–1987 E28 525i (110 kW, fuel injected)

2.8 litre

A 2.8 litre version of the M30, this appeared in 1968 in the then new E3 2800 and E9 2800CS. It has a bore of 86 mm, a stroke of 80 mm and a displacement of 2,788 cc (170.1 cu in). In the E24 628 CSi, it uses Bosch L-Jetronic fuel injection. Originally, two Solex Zenith "35/40 INAT" carburetors are used, the compression ratio is 9.0:1 and the engine produces 170 PS (125 kW) and 24.0 kg·m (235 N·m; 174 lb·ft).

Applications:

• 1968-1974 E3 2800
• 1971 E3 Bavaria
• 1968-1971 E9 2800CS
• 1975-1976 E12 528 (125 kW, carburetor)
• 1977-1979 E23 728 (125 kW, carburetor)
• 1976-1978 E12 528 (130 kW, carburetor)
• 1977-1978 E12 528i (129 kW, fuel injected, lower compression ratio, North America only)
• 1978-1981 E12 528i (135 kW, fuel injected)
• 1979-1986 E23 728i (135 kW, fuel injected)
• 1979–1987 E24 628CSi (135 kW, fuel injected)
• 1981-1987 E28 528i (135 kW, fuel injected)

3.0 litre

This version was produced from 1971 until 1992. It has a bore of 89 mm, a stroke of 80 mm and a displacement of 2986 cc. The first model to use the carburetted version of the 3 litre M30 was the E9 3.0CS. There was also the first fuel-injected M30 version for the CSi and later Si models, which uses the Bosch D-Jetronic fuel injection system.

Applications (carburettor)

• 1971-1975 E9 3.0CS
• 1972-1974 E3 3.0S
• 1972-1974 E3 Bavaria
• 1976–1979 E24 630CS (Pierburg 4A1 downdraft carburetor)
• 1977-1979 E23 730 (135 kW)

Applications (fuel injected)

• 1971-1975 E9 3.0CSi
• 1972-1973 E9 3.0CSL
• 1974-1975 E3 3.0Si
• 1975–1978 E12 530 (130 kW, South Africa only)
• 1975–1978 E12 530i (131 kW, North America only)
• 1976 E12 530 MLE (147 kW, South Africa only)
• 1977–1978 E24 630CSi (North America only)
• 1986–1992 E32 730i (138 kW)
• 1988–1990 E34 530i (not sold in North America)

M30B32

Despite having a capacity of 3210 cc, this engine appeared in many cars badged so as to suggest 3.3 litres of displacement, such as the 633i, 3.3 Li, and 733i. It has a bore of 89 mm, a stroke of 86 mm and a capacity of 3210 cc. In the E24 633CSi, it uses Bosch L-Jetronic fuel injection. The US version used L-Jetronic from 1978 until mid-1981, changing over to Motronic fuel injection in June of that year. The 1979 732i is BMW's first use of Bosch's Motronic fuel injection.

Applications:

• 1976–1984 E24 633CSi
• 1976-1977 E3 3.3 Li
• 1977-1979 E23 733i (145 kW)
• 1979 E12 533i
• 1979–1986 E23 732i (144 kW)
• 1983–1984 E28 533i (North America only)
• 1984-1986 E30 333i (145 kW, South Africa only)
• 1982 Cumberford Mantique prototype

M30B34

This engine has a bore of 92.0 mm, a stroke of 86.0 mm and a displacement of 3428cc. In the E24 635CSi, it uses Bosch Motronic 1.0 fuel injection.

Without catalytic converter
The version sold in Europe and most other markets used a 10.0:1 compression ratio and produced 160 kW (210 hp).

Applications:

• 1982-1986 E23 735i
• 1982-1986 E24 635CSi
• 1985-1988 E28 535i/M535i

With catalytic converter
The version sold in markets such as North America and Japan used an 8.0:1 compression ratio and produced 136 kW (182 hp).

Applications:

• 1982–1987 E24 635CSi
• 1982-1987 E23 735i
• 1985-1988 E28 535i
• 1985-1987 E23 735i
• 1986-1987 E23 L7
• 1987 E24 L6
• 1987-1988 E28 535is

M30B35

It has a bore of 92 mm, a stroke of 86 mm and a capacity of 3428 cc. In the E24 635CSi, it uses Bosch Motronic 1.3 fuel injection.

• 9.0:1 compression ratio
• 155 kW (208 hp) at 5,700 rpm
• 305 N·m (225 lb·ft) torque at 4,000 rpm
• 87 AKI / 91 RON octane fuel or better recommended

Applications:

• 1988–1989 E24 635CSi
• 1988–1992 E32 735i (155 kW)
• 1988–1993 E34 535i
• 1988-19?? Rayton Fissore Magnum 3.5

The BMW M21 is a six-cylinder-inline-diesel engine developed by BMW. The engine with swirl chamber injection is based on the otto engine M20 and was produced for BMW by the upper Austrian Steyr engine plant from 1983 to 1991. It was succeeded by the M51.

In the 1970s BMW decided to develop an engine, which would both be powerful and have a good fuel economy. This was caused by the oil crisis in 1973. In 1975 a group of BMW engineers started working on the M21 diesel engine, the otto engine M20 was taken as the basis. In 1983 at the IAA, the first passenger car was shown to the public which made use of the 85 kW M21. It was the E28 524td, which has a top speed of 180 km/h and reaches 100 km/h in 12,9 s. This 5er-BMW was the fastest series production diesel car in the world back in 1983. It has a fuel economy of 7,1 l /100 km.

 M21 is a water-cooled  six-cylinder inline engine made of gray cast iron with OHC valve control and vortex chamber injection . The cylinder head is designed according to the cross-flow principle . The camshaft is driven by a toothed belt, and operates two valves per cylinder.  Furthermore, the camshaft also drives the oil pump via a secondary shaft. In comparison with the M20 engine has the M21 reinforced connecting rods, pistons, valves, a reinforced cylinder head as well as increased seven-bearing Crankshaft with twelve counterweights. The M21 was a InstantStart equipped mentioned system that reduces the preheating time as compared to comparable diesel engines. The idling speed is regulated depending on the temperature. The fuel injection is in 1983 to 1987 built variants mechanically and from 1987  built charged variants of the M21 engine of a digital engine control device controlled that provides than the conventional injection control for a better torque.  The injection pump is a distributor injection pump ,  which the fuel pump is integrated.  It is driven by the toothed belt. The engine has a fuel cut . Garret turbochargers without intercooler charge some variants of the M21 engine, the engine with digital control unit has a slightly smaller turbocharger, which improves the response. 1985, BMW pursued the M21 engine as a sucker , which was particularly popular in countries with high car tax.  The naturally aspirated received the digital engine control unit until 1989. When charged M21 85% of the maximum torque are min at 1700 .  In addition to the radiator, the turbocharged M21 has an engine oil cooler. The electric starter provides 2200 W  . The generator is driven like the water pump via the toothed belt. The power steering pump has a separate V-belt. 

Technical description

The M21 is a water-cooled and swirl-chamber-injected six-cylinder-inline-diesel-engine with a cast iron block and OHC valvetrain. The camshaft is driven by a belt,each cylinder has one inlet and one outlet valve. Compared to the otto engine M20, the M21 has reinforced connecting-rods, cylinder heads, pistons, valves and a reinforced crankshaft with seven bearings.

For faster engine startup the M21 has a glowplug system called instant start, which reduces the time to reach starting temperature compared to similar diesel engines. The fuel is injected into swirl chambers.

A Garret turbocharger is used (without an intercooler). Initially, the M21 was only available as a turbocharged engine. In 1985, BMW introduced a naturally aspirated version of the M21, which was popular in countries with a high motor vehicle tax.

Initially, the fuel injection system was controlled mechanically. In 1987, this system was replaced by an electronic diesel control system,which increased the torque output by 10 N·m (7 lb·ft). The updated engine has a smaller turbocharger, which improves response.

Models

Applications:

• 1983 - 1988 E28 524td
• 1985 - 1988 E28 524d (naturally aspirated)
• 1985 - 1993 E30 324d (naturally aspirated)
• 1985 - 1993 E30 324td
• 1988 – 1991 E34 524td
• 1984 - 1985 Lincoln Continental Mark VII
• 1984 - 1985 Lincoln Continental
• 1986 - 1987 Vixen 21 TD and Vixen 21 XC
• 1989 - 1991 Bertone Freeclimber
• 1992 UMM Alter II (Very rare UMM model, only 4 were made)