BMW M30B30 Engine

Characteristics of the M30B30 engine

Engine reliability, problems and repairs

In the period from the early 70s to the late 80s, BMW cars with the index 30 and 30i were powered by the M30B30 engine, which is a large inline six with a working volume of 3 liters. This power unit is based on a cast iron cylinder block, the same as the M30B28, but with cylinders with a diameter of 89 mm. The crankshaft has a stroke of 80 mm, connecting rods – 135 mm, compression height of the piston – 42.8 mm.

The cylinder head is simple – SOHC 8V, no hydrocompensators, phase shifters and other modern nonsense. M30B30 camshafts: phase 260, lift 7.4 mm. The injectors’ capacity is 192 cc. In the drive of the timing chain was used. The fuel supply system was both carburetor and injector. The first one was produced until 1979, injectors – during the whole production period and received the widest distribution.

The carbureted model M30B30 appeared together with the injector model in 1971, had a compression ratio of 9 and developed 180 hp at 6000 rpm. The injector model came with Bosch D-Jetronic injection and a compression ratio of 9.5, which made 200 hp at 5,500 rpm.

Since 1976, carburetors Solex Zenith 35/40 INAT were replaced by Solex DVF-4A1, the power of such motors increased to 184 hp at 5800 rpm, and since 1979, instead of carbureted M30B30 began to install injector M30B28.

In 1975, the injector M30B30s were modified: the compression ratio was reduced to 9, injection was replaced by Bosch L-Jetronic and it affected the power, which decreased to 195 hp at 5800 rpm.

In 1986, the M30B30 engine was installed on the new, at that time, BMW 730i E32. This engine had a compression ratio of 9.2 and developed 197 hp at 5800 rpm. A version with a catalytic converter and compression ratio 9 was produced, its power was 188 hp at 5800 rpm.

Later, on the basis of 3-liter engine were built M30B32, M30B35 and other famous engines of M30 series.

M30B30 was taken out of production in 1994, together with BMW 730i E32 and instead of it BMW 730i E38 was produced, with a new 3-liter engine with V8 configuration – M60B30.

BMW M30B30 engine problems

• Overheating. This problem is inherent in many BMW inline 6-cylinder engines and it is not worth to run it – will lead the cylinder head. The cause of the malfunction in a dirty radiator, pump, thermostat or in air plugs in the cooling system.
• Cracks in the cylinder block. They are formed around the threads for the cylinder head bolts, due to the failure to remove oil from the thread wells, after disassembly of the engine. Symptoms indicating the appearance of cracks in the M30: antifreeze leaving, emulsion in the oil. You can try to solve the issue by repair, but it is more reliable and correct to buy a used cylinder block without cracks.

Given the very advanced age of BMW M30 motors, to the above is added wear and tear of everything that is possible: most often problems occur in the mechanism of gas distribution, with the subsequent inability to adjust the valve, it is solved by replacing the eccentrics, worn valves, guide sleeves. Malfunctions associated with the DMRV are also not uncommon.

Benefits:

1. Reliability and durability: Thanks to the cast-iron cylinder block, the M30 engine has high reliability and durability, which is confirmed by a practical resource of more than 400 thousand kilometers.
2. High tuning potential: The M30 engine has significant tuning potential, achieving over 800 hp
3. Easy maintenance: Relatively simple design and the prevalence of spare parts make maintenance and repair of the M30 engine accessible and uncomplicated.
4. Wide range of applications: The engine has been installed in various BMW models such as the BMW 530i E34, BMW 630 E24, BMW 730i E32, BMW E3 3.0, BMW E9 3.0, BMW 530i E12, and BMW 730 E23.

Disadvantages:

• High fuel consumption: Especially in urban conditions, where consumption can reach 16.3 liters/100 km, making it not the most economical engine.
• Oil consumption: The engine can consume up to 1000 grams of oil per 1000 km, which requires regular oil level checks.
• Lack of modern environmental standards: The engine does not meet modern environmental standards, which can be a problem in regions with strict emission regulations.
• Two-valve design: Less efficient than modern four-valve engines.

Recommendations for use:

1. Timely oil changes: It is recommended to change the oil every 7000-10000 km using oils that meet specifications (5W-30, 5W-40, 10W-40, 15W-40).
2. Oil consumption control: Check the oil level regularly to avoid problems with oil shortage.
3. Maintaining the cooling system: Make sure the cooling system is working properly to avoid engine overheating and related problems.
4. Use quality fuel: Use only high quality fuel to ensure stable operation and engine longevity.

At this point, all BMW M30 engines have outlived their useful life, despite the fact that it can easily exceed 500,000 kilometers. Also, cars with M30 are often operated quite harshly (especially E34), this additionally imposes its imprint.

The BMW M30 itself is a great engine for its time, but age takes its toll. If you want to buy a BMW and you have to choose between M30 or M50 (and other motors of this series), you should take a more recent M50.

Tuning the BMW M30B30 engine

M30B30 Stroker

The three-liter M30, by means of ingenuous manipulations, can be turned into an M30B35. To do this, you need to buy pistons, crankshaft and brains from M30B35, as well as bore the cylinder block to 92 mm. The connecting rods remain standard, the 3.5 liter motor has pistons with lower compression height. If you leave the cylinders stock and install only a crankshaft with a stroke of 86 mm, as well as pistons from M30B32, you will get M30B32. There is no great sense in it, because there is a lot of fiddling, and the increase is about 10 hp, if you make a stroker, then up to 3.5 liters (although here too, do not expect a big increase). After increasing the working volume, it would be good to buy the M30B35 cylinder head, with increased intake valves. And if it came to the head, it is desirable to refine it, to install a camshaft Schrick 284/280, springs and reinforced rockers, to make a normal straight-through exhaust, cold intake and adjust the brain. In the end, the remodeling will cost quite a bit, and you’ll get a boost in the neighborhood of 50-60 hp.

Bottom line: buy M50B25 or M54B30, save time.

You can build a turbo project based on the M30B30 just like with the M30B35.

ENGINE RATING: 4+