The M10B20 is a 2.0 L petrol inline-4 from BMW's M10 family, built 1962–1988 and rated at 125 hp and 170 Nm. It powered the BMW E12 520, BMW E21 320 and BMW E28 520.
This guide is about the M10B20 specifically: its specification, the cars that use it, how it differs from the other M10 versions, what to check, prices from our stock and fitment answers for each model. For the history of the whole family, read our M10 guide.
- Capacity and layout: 2.0 L, inline-4, naturally aspirated
- Output: 125 hp and 170 Nm
- Production: 1962–1988
- Fitted to: 3 models across 3 chassis generations
- In our stock: ask the desk for the next arrival
M10B20 specifications
| Item | Value |
|---|---|
| Engine code | M10B20 |
| Family | M10 |
| Capacity | 2.0 L |
| Layout | Inline-4 |
| Fuel | Petrol |
| Aspiration | Naturally aspirated |
| Power | 125 hp |
| Torque | 170 Nm |
| Specific output | 63 hp per litre |
| Production | 1962–1988 |
| Models | 3 |
M10B20: 2.0 L, inline-4, petrol, naturally aspirated. Output is 125 hp with 170 Nm of torque, and production ran from 1962 to 1988. That is about 63 hp and 85 Nm per litre, a relaxed tune aimed at torque, durability and economy. Within the M10 family, it is the most powerful version, while the M10B15 (80 hp), M10B16 (90 hp) and M10B18 (105 hp) are milder. It was fitted to the BMW E12 520, BMW E21 320 and BMW E28 520.
What the code M10B20 means
- M marks an M-series code, the naming BMW used for its engine families up to the early 2000s.
- 10 is the family number.
- B stands for petrol (from the German Benzin).
- 20 is the capacity in decilitres, so 2.0 litres.
Which BMW models use the M10B20
| Model | Generation | Built |
|---|---|---|
| BMW E12 520 | first 5 Series | 1972–1981 |
| BMW E21 320 | first 3 Series | 1975–1983 |
| BMW E28 520 | second 5 Series | 1981–1988 |
In the E12 first 5 Series (1972–1981), the M10B20 powered the 520. Engines from other models fit the E12 as long as the sump, mounts and ancillaries match, which we check against your VIN. All E12 engines
In the E21 first 3 Series (1975–1983), the M10B20 powered the 320. Engines from other models fit the E21 as long as the sump, mounts and ancillaries match, which we check against your VIN. All E21 engines
In the E28 second 5 Series (1981–1988), the M10B20 powered the 520. Engines from other models fit the E28 as long as the sump, mounts and ancillaries match, which we check against your VIN. All E28 engines
M10B20 compared with other M10 versions
| Code | Capacity | Power | Torque | Years |
|---|---|---|---|---|
| M10B15 | 1.5 L | 80 hp | 118 Nm | 1962–1964 |
| M10B16 | 1.6 L | 90 hp | 130 Nm | 1962–1988 |
| M10B18 | 1.8 L | 105 hp | 145 Nm | 1962–1988 |
| M10B20 | 2.0 L | 125 hp | 170 Nm | 1962–1988 |
M10B20 or M10B18?
The M10B18 has 20 hp less than the M10B20 (105 against 125 hp), from 1.8 L instead of 2.0 L, and was built 1962–1988. A different capacity means a different crankshaft, pistons or head, and different software. It can be fitted as an upgrade with the matching engine control unit and wiring, but it is a conversion rather than a straight replacement.
M10B20 or M10B16?
The M10B16 has 35 hp less than the M10B20 (90 against 125 hp), from 1.6 L instead of 2.0 L, and was built 1962–1988. A different capacity means a different crankshaft, pistons or head, and different software. It can be fitted as an upgrade with the matching engine control unit and wiring, but it is a conversion rather than a straight replacement.
M10B20 or M10B15?
The M10B15 has 45 hp less than the M10B20 (80 against 125 hp), from 1.5 L instead of 2.0 L, and was built 1962–1964. A different capacity means a different crankshaft, pistons or head, and different software. It can be fitted as an upgrade with the matching engine control unit and wiring, but it is a conversion rather than a straight replacement.
Common M10B20 problems
The M10B20 shares its weak points with the rest of the M10 family. These are the faults to check on a used unit and on your own engine. The full explanation of each is in the M10 guide.
| Known fault | What to check |
|---|---|
| Camshaft and rocker wear | Remove the rocker cover and look at the lobes and rocker faces for pitting or a polished flat. |
| Timing chain guides and tensioner | Listen at the front cover during the first seconds after a cold start. |
| Warped head after overheating | Ask for a compression or leak-down test and check the coolant for oil. |
| Valve stem seals | Watch the exhaust for the first ten seconds after a cold start. |
| Oil leaks from age | Look under the bellhousing and around the front cover for fresh oil. |
Camshaft and rocker wear. Lobes and rocker pads wear when the oil spray bar is blocked or oil changes were neglected. A worn cam loses lift and the engine feels flat above 4,000 rpm.
M10B20 maintenance
- A good 15W-40 or 20W-50 mineral or semi-synthetic oil with zinc protection for flat-tappet cams, about 4.0 to 4.5 litres with filter.
- Oil every 5,000 to 7,500 km for a classic driven in short trips; valve clearances checked every 15,000 km.
- Single-row or duplex timing chain on the front of the engine; no scheduled change, inspect guides when the head is off.
Will the M10B20 fit my car?
Will the M10B20 fit my BMW E12 520?
The M10B20 is the original engine for the BMW E12 520, which makes it the straightforward choice. The first 5 Series was built 1972–1981, and the M10B20 was produced 1962–1988, so check that your car's build date falls inside that window. Confirm the drive type (rear-drive or xDrive), the gearbox (manual or automatic) and the emissions standard, because these can change the sump, the flywheel and the software. Send us the VIN and we check all of it for you.
How much is a replacement engine for a BMW E12 520?
We do not have an M10B20 on the shelf for the E12 520 at the moment. Units arrive regularly; send us your VIN and we will tell you when the next one is ready and what it will cost, including delivery.
Will the M10B20 fit my BMW E21 320?
The M10B20 is the original engine for the BMW E21 320, which makes it the straightforward choice. The first 3 Series was built 1975–1983, and the M10B20 was produced 1962–1988, so check that your car's build date falls inside that window. Confirm the drive type (rear-drive or xDrive), the gearbox (manual or automatic) and the emissions standard, because these can change the sump, the flywheel and the software. Send us the VIN and we check all of it for you.
How much is a replacement engine for a BMW E21 320?
We do not have an M10B20 on the shelf for the E21 320 at the moment. Units arrive regularly; send us your VIN and we will tell you when the next one is ready and what it will cost, including delivery.
Will the M10B20 fit my BMW E28 520?
Yes, the BMW E28 520 left the factory with the M10B20, so an M10B20 from another car is the direct replacement. The second 5 Series was built 1981–1988, and the M10B20 was produced 1962–1988, so check that your car's build date falls inside that window. Confirm the drive type (rear-drive or xDrive), the gearbox (manual or automatic) and the emissions standard, because these can change the sump, the flywheel and the software. Send us the VIN and we check all of it for you.
How much is a replacement engine for a BMW E28 520?
We do not have an M10B20 on the shelf for the E28 520 at the moment. Units arrive regularly; send us your VIN and we will tell you when the next one is ready and what it will cost, including delivery.
M10B20 prices
We do not have an M10B20 on the shelf at the moment. Send us your VIN or the code you need and the desk will tell you when the next unit arrives and what it will cost.
Buying a used M10B20: checklist
- Photographs from every side. Good suppliers photograph the actual engine you will receive. Look for the block stamp, the sump, the timing cover and any broken brackets or connectors in the pictures.
- Ask how the donor car was damaged. Most good used engines come from cars with body damage. A front-end impact can crack sensors, the timing cover or the sump; a rear or side impact usually leaves the engine untouched. The yard records the damage on each unit.
- Sump, oil pickup and drive variants. Rear-drive, xDrive and front-drive cars can use different sumps, oil pickups and engine mounts even with the same engine code. Check that the sump matches your subframe and front axle.
- Gearbox and flywheel match. Manual and automatic engines differ at the flywheel or flexplate, and sometimes at the crankshaft spigot. Make sure the engine you buy matches your gearbox or that you transfer the right parts.
- Look at the oil and coolant. Clean oil without metal particles and coolant without oil are good signs. Milky oil, oily coolant or a burnt smell mean the engine needs further checks before it is fitted.
- Timing chain noise. Listen for a rattle at the front of the engine for the first seconds after a cold start. On an engine that cannot be run, look at the chain guides through the oil filler or with the valve cover off.
- Originality and numbers. For collectible cars, the engine number and correct ancillaries add value. Photograph the stamp and keep it with the car's documents.
Questions about the M10B20
What should I know about the BMW M10 engine?
BMW M10 four-cylinder petrol engines for E30 316 and E21. We list one version: M10B18 (1.8 liter (1,766 cc), 77 kW (105 HP), 1975 to 1988).
Because there is only one version, the code is easy to match. You still need the engine computer and wiring that suit your car.
The M10 family was used in chassis E30 and E21. The photos on each listing show the actual engine, not a stock picture. The yard checks the code, records what is bolted on, and seals the openings before the engine is offered.
Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.
How much is a replacement M10B18 engine for a BMW E21 316?
A used M10B18 for the BMW E21 316 costs from about 800 € to 1.450 € in our yard. The price depends on the year, the mileage and the parts that come with the engine.
Shipping is a flat 249 € per order. It is added once at checkout and printed on the invoice, so there is no extra fee later. Inside the EU there is no import duty. Outside the EU, the receiver pays local duty and VAT.
A replacement engine is often much cheaper than rebuilding a damaged one, and much faster. The M10B18 you buy is photographed and checked in Hamburg before it is listed.
Eligible engines come with a 12 months warranty from the delivery date. It covers internal mechanical failure under normal use and correct fitting by a qualified mechanic or workshop. Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.
See all M10 Engines · Search M10B18 in the shop
What comes with a used M10B18 engine?
Each M10B18 is sold as described on its own listing. The yard writes down the parts that are fitted to that unit, such as the turbo, the injectors, the manifolds or the alternator, so you know what arrives.
Some units are long engines with few ancillaries, others are more complete. If you need a part that is not listed, ask the desk. We often have the matching items in the yard.
Every engine is drained, sealed at each opening, strapped to a heat-treated pallet and shrink-wrapped, then photographed before it leaves the yard.
On delivery, the carrier brings the pallet to the kerb or a loading bay. Please have a forklift, a pallet truck or an engine crane ready.
See all M10 Engines · Search M10B18 in the shop
Is the BMW M10B18 a diesel or petrol engine?
The M10B18 is a petrol engine. It is a 1.8 liter (1,766 cc) inline 4, SOHC, 8 valve unit with no turbo (naturally aspirated), and it was built to the Euro 1 emission standard.
The emission standard matters for registration and for low-emission zones in many cities. When you replace an engine with the same code, the car keeps the same paperwork and the same emission class.
Petrol versions need the correct catalytic converters and oxygen sensors on the car to stay legal and to keep the engine computer happy. Reuse the parts from your car if they are in good condition.
If you are not sure which version you need, send us your VIN. We tell you the right code for free.
See all M10 Engines · Search M10B18 in the shop
How much is a replacement M10B18 engine for a BMW E30 316?
A used M10B18 for the BMW E30 316 costs from about 800 € to 1.450 € in our yard. The price depends on the year, the mileage and the parts that come with the engine.
Shipping is a flat 249 € per order. It is added once at checkout and printed on the invoice, so there is no extra fee later. Inside the EU there is no import duty. Outside the EU, the receiver pays local duty and VAT.
A replacement engine is often much cheaper than rebuilding a damaged one, and much faster. The M10B18 you buy is photographed and checked in Hamburg before it is listed.
Eligible engines come with a 12 months warranty from the delivery date. It covers internal mechanical failure under normal use and correct fitting by a qualified mechanic or workshop. Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.
See all M10 Engines · Search M10B18 in the shop
How much is a replacement M10B18 engine for a BMW E21 318i?
A used M10B18 for the BMW E21 318i costs from about 800 € to 1.450 € in our yard. The price depends on the year, the mileage and the parts that come with the engine.
Shipping is a flat 249 € per order. It is added once at checkout and printed on the invoice, so there is no extra fee later. Inside the EU there is no import duty. Outside the EU, the receiver pays local duty and VAT.
A replacement engine is often much cheaper than rebuilding a damaged one, and much faster. The M10B18 you buy is photographed and checked in Hamburg before it is listed.
Eligible engines come with a 12 months warranty from the delivery date. It covers internal mechanical failure under normal use and correct fitting by a qualified mechanic or workshop. Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.
See all M10 Engines · Search M10B18 in the shop
Which cars use the BMW M10B18 engine?
BMW fitted the M10B18 to the BMW E30 316, BMW E30 318i, BMW E21 316 and BMW E21 318i. These cars were built with this engine from about 1975 to 1988.
The badge on the boot is not enough to be sure. The same model name can hide two different engines, for example after a facelift or a change in emission rules. Always read the engine code stamped on the block, or look it up with your VIN.
The M10B18 is the only M10 version we list, which makes it easy to pick, but the wiring and the engine computer still need to match your car.
Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.
See all M10 Engines · Search M10B18 in the shop
How much is a replacement M10B18 engine for a BMW E30 318i?
A used M10B18 for the BMW E30 318i costs from about 800 € to 1.450 € in our yard. The price depends on the year, the mileage and the parts that come with the engine.
Shipping is a flat 249 € per order. It is added once at checkout and printed on the invoice, so there is no extra fee later. Inside the EU there is no import duty. Outside the EU, the receiver pays local duty and VAT.
A replacement engine is often much cheaper than rebuilding a damaged one, and much faster. The M10B18 you buy is photographed and checked in Hamburg before it is listed.
Eligible engines come with a 12 months warranty from the delivery date. It covers internal mechanical failure under normal use and correct fitting by a qualified mechanic or workshop. Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.
See all M10 Engines · Search M10B18 in the shop
Which years were BMW M10 engines made?
BMW built the M10 engines we list from about 1975 to 1988. The M10B18 ran from 1975 to 1988.
They went into chassis E30 and E21. The exact year of a car matters, because BMW sometimes changed the engine version or its parts in the middle of a model's life.
Each listing in our yard names the engine year, so you can match it to the build date of your car.
Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.
What should I check on a used BMW M10 engine?
Start with the basics: the engine code on the block, the recorded mileage and the photos. Make sure the code matches your car and the parts you need are on the unit.
On an M10 petrol engine, a fitter usually checks the spark plugs, the coils, the timing side and the oil seals. These parts are easy to check before fitting and easy to change if needed.
Ask the desk for more pictures of any listing. We are happy to show the stamp, the ports and the ancillaries before you decide. An inspection certificate can travel with the order on request.
Once fitted, change the oil and filter early and drive gently at first. Report any problem right away so the warranty stays valid.
See all M10 Engines · Inspection certificate
Are there other versions of the BMW M10B18?
In our yard the M10B18 is the only listed version of the M10 family. It makes 77 kW (105 HP) and 145 Nm, and was built from 1975 to 1988.
Engines in one family share a basic block, but the turbo, the injection, the sensors and the engine computer can differ. A higher power version often has different pistons, a bigger turbo or a different fuel system.
This is why we ask for the exact code. Fitting a different version can work, but the wiring, the software and sometimes the gearbox must be changed to match.
Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.
See all M10 Engines · Search M10B18 in the shop
How long does delivery of an M10B18 engine take?
Orders confirmed before 14:00 CET on a working day leave Hamburg the same day. Later and weekend orders leave the next working day. Delivery to the Netherlands, Belgium, Germany, France, Luxembourg and Denmark takes 1 to 3 working days.
Spain, Italy, Portugal, Poland, Czechia, Austria, Ireland, the Nordics and the Baltics take 2 to 5 working days. Greek and Spanish islands, Malta, Cyprus and remote areas take 4 to 8 working days. The UK and other countries outside the EU are quoted one by one.
Shipping is a flat 249 € per order. It is added once at checkout and printed on the invoice, so there is no extra fee later. Every engine is drained, sealed at each opening, strapped to a heat-treated pallet and shrink-wrapped, then photographed before it leaves the yard.
You get a tracking number when the pallet is collected. Check the wrapping before you sign, and note any damage on the paperwork.
See all M10 Engines · Search M10B18 in the shop
Delivery, warranty and payment
Before an M10B20 leaves our Hamburg yard it is drained of oil and coolant, every opening is sealed, and it is strapped to a pallet and wrapped. We send photographs of the packed unit and the tracking details.
Delivery is door to door and included in the price. Most European addresses receive the engine within five to ten working days; Germany and its neighbours are usually faster.
A 12-month warranty covers eligible internal failure when the engine is fitted by a qualified workshop with new fluids and filters. You can pay by card, bank transfer or crypto and receive the invoice by email straight away.
