Engines

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Contents

List of Engines

To maintain and repair your engine, you need to know what lump you have under the bonnet of your E30. Below is each engine, listed by model and year, for the E30. By clicking on the engine, you will have access to information regarding Maintenance, Cooling systems, Fuel, Intake, Exhaust and Electrical systems, as well as Common Problems and Upgrades.


NameEngine codeVolumeEngineValvetrainFuelOutputTorqueYears
316M10B181766cc4cylSOHC 8VPetrol99hp (66kW) @4500 rpm103ft/lb (140Nm) @4250 rpm1982–1987
316iM40B161596cc4cylSOHC 8VPetrol102hp (75kW) @4500 rpm105ft/lb (140Nm) @4250 rpm1987–1994
318iM10B18
M40B18
1766cc
1796cc
4cylSOHC 8VPetrol104hp (77kW) @4500 rpm
113hp (85kW) @4500 rpm
103ft/lb (140Nm) @4250 rpm
122ft/lb (165Nm) @4250 rpm
1982–1990
1987–1995
318iSM42B181766cc4cylDOHC 16VPetrol140hp (104kW) @4500 rpm127ft/lb (172Nm) @4250 rpm1989–1991
320iM20B201990cc6cylSOHC 12VPetrol123hp (92kW) @5800 rpm
127hp (95kW) @6000 rpm
125ft/lb (170Nm) @4000 rpm
120ft/lb (164Nm) @4300 rpm
1982–1985
1985–1991
320iSS141990cc4cylDOHC 16VPetrol192hp (143kW) @6750 rpm155ft/lb (210Nm) @4750 rpm1982–1990
323iM20B232316cc6cylSOHC 12VPetrol139-150hp (104-110kW) @4500 rpm0ft/lb (0Nm) @4000 rpm1982–1985
325eM20B272693cc6cylSOHC 12VPetrol127hp (95kW) @4250 rpm169ft/lb (230Nm) @3200 rpm1982–1990
325iM20B252494cc6cylSOHC 12VPetrol169hp (125kW) @5800 rpm163ft/lb (222Nm) @4300 rpm1982–1990
325iXM20B252494cc6cylSOHC 12VPetrol169hp (125kW) @5800 rpm163ft/lb (222Nm) @4300 rpm1982–1990
M3S142302cc4cylDOHC 16VPetrol197hp (147kW) @6750 rpm
212hp (158kW) @6750 rpm
176ft/lb (0Nm) @4750 rpm
170ft/lb (0Nm) @4600 rpm
1986–1988
1989–1991
M3 EvolutionS142302cc4cylDOHC 16VPetrol197hp (147kW) @6750 rpm176ft/lb (0Nm) @4750 rpm1987–1987
M3 Evolution IIS142302cc4cylDOHC 16VPetrol217hp (162kW) @6750 rpm181ft/lb (0Nm) @4750 rpm1988–1988
M3 Sport EvolutionS142467cc4cylDOHC 16VPetrol235hp (175kW) @6750 rpm177ft/lb (0Nm) @4750 rpm1990–1990
324dM21D242443cc6cylSOHC 12VDiesel84hp (63kW) @4600 rpm112ft/lb (152Nm) @2400 rpm1985–1993
324tdM21D242443cc6cylSOHC 12VDiesel114hp (85kW) @4800 rpm162ft/lb (220Nm) @2400 rpm1985–1993


If you are still unsure about which engine you have in your car, you can find the number on the engine itself.


For more comprehensive info on every BMW engine, check out this file

Servicing

All engines need looking after, and while simple jobs like oil changes are standard to all E30s, some jobs are specific to either the 4-cylinder or 6-cylinder engines. Click on the engine model for your car to get specific information:

Special engines

The following topics are standard maintenance tasks to keep all engines running smoothly

Ancillaries

The main body of the engine is surrounded by ancillary components to supply fuel, air and spark, as well as devices for lubrication and cooling. The overall engine is controlled by an engine management system.

Fuel

Main article: Fuel

All cars need motion lotion. This is stored in a tank under the rear seats. From there, the fuel is delivered via a fuel pump, through a filter and hard pipes, to the engine bay. From there the pipes are made from rubber, and enter a fuel rail. At times controlled by the ECU, injectors will squirt fuel into the relevant cylinder of the engine. From the other end of the fuel rail is a fuel pressure regulator and return fuel line, which returns fuel to the tank, making a closed loop.

On carburettor engines, the fuel rail, injectors and fuel pressure regulator are replaced by a carburettor, which connects to the inlet manifold, and the fuel pump is mounted in the engine bay.

Air

Main article: Intake

All engines breathe. When you press the accelerator pedal, you are not controlling the fuel (as some think) but the amount of air the engine can take in. Fuel needs oxygen to burn, so no oxygen means no burn.

On injected engines, air enters the system through a filter box at the front of the engine bay. Included into this filter box is an Air Flow Meter which measures how much air is coming in, and sends this data to the ECU. From there the air enters a large rubber distribution pipe connected to a number of ancillaries and the Throttle Body. The Throttle body is a cable-operated flap (connected to your accelerator pedal) which allows air into the engine when the pedal is pressed. Air enters the intake manifold which supplies air to all cylinders in the engine head.

On carburettor engines, the AFM and throttle body are replaced by a carburettor. Carburettors use a venturi effect (like blowing over an empty bottle to make it whistle), using air flow to suck fuel into the intake manifold.

Spark

Main article: Ignition

To make the fuel and air mixture burn, it must be ignited with a spark. This ignition system uses a standard distributor design.

The engine's electrical system charges a large capacitor, known as a coil, mounted at the front of the engine bay. This coil is directly connected to a rotating mechanical distributor, which works like a clock with one hand. For those who have seen the film Back To The Future, the moment the clock's hands strike the right point, a massive electrical charge is delivered through a cable, called an HT Lead, to a spark plug, which converts the charge into a spark. The number of points directly correlates the number of cylinders in the engine, as each cylinder requires its own HT lead and spark plug.

The firing of the distributor must be in time with the injection of air and fuel in the cylinder so that the combustion provides the maximum force. Incorrect firing can cause damage to the valves.

On injected engines, the timing is controlled by the ECU, allowing for retarding or advancement of the spark. On carburettor engines, the timing is mechanically matched to the cam shaft.

On M42 engines, the coil, distributor, HT leads and spark plugs are replaced with coil packs which generate and deliver a spark for each cylinder, controlled by the ECU.

Starter

Main article: Starter

Your petrol motor needs an electric motor to get it started. This motor spins the engine up to the speed needed for normal combustion to work - once those are happening, the starter will disengage.

The starter for all E30 engines sits on the intake side of the engine, and is bolted to the gearbox. It has direct heavy-duty wiring to the alternator and battery, and grounds through the engine block to the car chassis. It is triggered by wiring directly from the ignition switch.

Starters are specific to each engine, because the gear teeth of the starter cog has to match the teeth on the engine flywheel. What's more, there is a difference between early and late M20 starters due to a change in flywheel in 1987.

Exhaust

Main article: Exhaust

The exhaust allows all of the waste gases to leave the engine; if you didn't let that happen, the engine would explode like a pressure cooker. But it's not just a simple case of letting off steam; the pressure and speed with which these gases leave the system is crucial for smooth engine running.

A wide range of exhausts were fitted to E30s; two-and three-piece units, twin or single pipes, with or without catalytic converters and therefore with or without Lambda sensors. There are also a variety of aftermarket components such as improved exhaust manifolds and "tuning" backboxes to give a distinctive exhaust note when driving.

Engine Management

Main article: Engine Management

The Engine Management system on injected engines is a rudimentary electrical brain called an ECU. It receives data from various sensors in the engine and drivetrain, and controls Fuel and Spark based on a set of parameters, known as a map, inside the ECU chip.

On carburettor engines, there is no Engine Management system.

Cooling

Main article: Cooling

The engine has an optimal temperature range, where the heat of the block helps the fuel to evaporate and ignite. Heat is also good for thinning the oil, allowing it to penetrate and lubricate all the small nooks and crannies of the engine. However, too hot an engine will cause the metal components to wear quickly, and can cause failure of seals and gaskets, or even cracks in the metal such as the head.

For this reason, the engine is cooled with a water circuit. The engine block is filled with water channels, which carry coolant in and out of the engine. The system is pressurised with a water pump (driven by the timing chain or belt), which delivers the water to a radiator mounted at the front of the engine.

The pressure, or flow, of the system is regulated by a thermostat. This simple valve is controlled by the ECU, which takes data from a thermometer known as the Blue Plug and uses these readings to control the heat as well as the fuelling of the engine. If the Blue Plug reads cold, more fuel is added to help the engine run in cold conditions.

Under hard load, the natural air flow over the radiator may not be enough to cool the system. For this purpose, there is a fan behind the radiator. Again, readings from the Blue Plug tell the ECU when the fan should operate.

Oil

Main article: Oil

The internals of an engine are complex moving parts, rotating thousands of times a minute with metal rubbing on metal. Without oil, these metal components would lock solid, causing irreparable engine damage in most cases. A well lubricated engine will deliver power smoothly and last for many years.

Upgrades

For many, BMWs engines were as perfect as possible, and power upgrades are not easy to come by. Considering the youngest of these engines is now 17 years old, restoring the engine to its original condition will provide better power upgrades than any aftermarket accessories, in terms of Pound per hp.

With that in mind, there are some upgrades specific to each engine. Check out the relevant page for your engine for more info.

Engine Swaps

Main article: Engine Swaps

While every E30 is a sublime driving machine, the desire for more power leads many to look at their options. Since many E30 engines are unsympathetic to "tuning" without spending serious cash, many owners look towards swapping their old engines for alternative BMW units. If you're thinking about this, take a look at the current option of engine swaps.

Aside from swapping between engines within the E30 line-up, the following BMW engines have also proved to fit under the bonnet:

Troubleshooting

Main article: Troubleshooting Engines

You put the key in and nothing happens. Or she coughs and splutters but refuses to start. If your motor refuses to co-operate, work your way through our Engine Troubleshooting guide to find out why.