Characteristics of the M40B18 engine
| Manufacturing | Steyr Plant |
| Engine make | M40 |
| Years of manufacture | 1987-1994 |
| Cylinder block material | cast iron |
| Power system | injector |
| Type | row |
| Number of cylinders | 4 |
| Valves per cylinder | 2 |
| Piston stroke, mm | 81 |
| Cylinder diameter, mm | 84 |
| Compression ratio | 9 |
| Engine displacement, cc | 1796 |
| Engine power, hp/rpm | 113/5500 |
| Torque, Nm/rpm | 162/4250 |
| Fuel | 92 |
| Environmental regulations | – |
| Engine weight, kg | ~132 |
| Fuel consumption, l/100 km (for 318i E30) – city – highway – mixed. |
10.3 6.7 8.6 |
| Oil consumption, gr./1000 km | to 1000 |
| Engine oil | 5W-30 5W-40 10W-40 15W-50 |
| How much oil in the engine, liters | 4.0 |
| Oil change is carried out, km | 7000-10000 |
| Engine operating temperature, deg. | 90-95 |
| Engine life, thousand kilometers – according to the factory data – in practice |
– 300+ |
| Tuning, hp. – potential – without loss of resource |
150+ n.d. |
| Motor installed | BMW 318i E30 BMW 318i E36 BMW 518i E34 |
Reliability, problems and repair of the BMW M40B18 engine
The first inline four-cylinder engine of the M40 family, the big brother of the M40B16, developed in 1987 as a replacement for the obsolete M10 series. The engine is based on a cast iron cylinder block, covered by an 8-valve head with a single camshaft and hydrocompensators (valve adjustment is not required on the M40). The diameter of inlet valves is 42 mm, exhaust valves 36 mm. Characteristics of camshafts BMW M40: phase 244/244 lift 10.6/10.6 mm.
Unreliable belt is used in the timing drive, which requires constant monitoring and replacement together with the roller, on average, once every 40 thousand kilometers. If this problem is not taken seriously, the risk of timing belt breakage and valve bending increases.
This motor was used on BMW cars with index 18i.
Parallel to the M40B18, since 1989 a more powerful version of the 1.8-liter engine – M42B18, for sports 18i, was produced.
In 1992, a replacement for the M40 engine was released, the updated M43B18.
Problems and disadvantages of BMW M40B18 engines
Engine knocking
A worn camshaft, rocker arms and hydrocompensators are often to blame for the various M40 noises. Check.
Swimming revs
Check the ducting on the DMRV for continuity, there may be an air intake. Further inspect the DMRV, lambda-probe, the state of the throttle valve and CCH. In addition, the problem of M40 revolutions is hidden in the difficult rotation of the camshaft.
Drops in acceleration
The main reason for problems with engine dynamics is the injectors, most likely they require cleaning.
Overheating
Search for the cause should begin with an inspection of the condition of the radiator, pump, thermostat, check the cooling system for plugs, check the condition of the plastic tubes of the cooling system.
Not starting
Look for the problem in the gas pump, plugs, high voltage wires, ignition coil.
Don’t forget about the all-too-familiar problem with the not-so-reliable timing belt described above. Add to this the age of the motor and at the output we get not the most successful acquisition.
The BMW M40 engine itself is reliable, its resource is about 300 thousand kilometers, in some cases it is possible and more. Nevertheless, almost all BMW M40B18 to date have crossed this mark and trouble-free operation, most likely, you can forget.
Tuning BMW M40B18 engine
Stroker
It is necessary to specify at once, tuning of M40 is far not the most profitable and successful investment of means, it is much easier to buy a contract engine BMW M50 for example, to weld and to know no troubles.
If your hands are stretched to refine your 1.8 liter, then stroker is your choice. To increase the volume up to 2.1 liters you need to buy a crankshaft from M47D20 (stroke 88 mm), S50B30 pistons, connecting rods M44B19. The cylinder head, timing, intake, exhaust, ECU from M44 (or M42). All this together, together with boring the block to 86 mm, will give 150-160 hp.
To turbocharge or blow into the M40 with a compressor is even more expensive and crazy, only the cylinder block will remain factory, and at the output we will get not too much power and lack of reliability.
MOTOR RATING: 4