The BMW 323i in the third 3 Series generation (E36, built 1990–2000) was built with one engine, the M52B25: a 2.5 L petrol inline-6 with 170 hp.
This guide tells you which engine your 323i has, what goes wrong with it, what a replacement costs from our stock and what else to plan for when you fit one.
- Generation: third 3 Series, 1990–2000
- Body styles: E36 (saloon, Touring, coupé, convertible, Compact)
- Engines: M52B25
- Output: 170 hp
- Replacement engines in stock: 6 from 1.413,00 €
Which engine is in your 323i?
| Engine code | Built | Power | Torque | Type |
|---|---|---|---|---|
| M52B25 | 1995–2000 | 170 hp | 245 Nm | 2.5 L petrol inline-6, naturally aspirated |
M52B25 in the 323i
The M52B25 was used in the E36 323i, built 1995–2000. It is a 2.5 L naturally aspirated petrol inline-6 with 170 hp and 245 Nm.
Reading the code: M marks an M-series code, the naming BMW used for its engine families up to the early 2000s; 52 is the family number; B stands for petrol (from the German Benzin); 25 is the capacity in decilitres, so 2.5 litres.
323i engines by model year
| Model year | Engine |
|---|---|
| 1995 | M52B25 (170 hp) |
| 1996 | M52B25 (170 hp) |
| 1997 | M52B25 (170 hp) |
| 1998 | M52B25 (170 hp) |
| 1999 | M52B25 (170 hp) |
| 2000 | M52B25 (170 hp) |
The 323i kept the same engine for the whole E36 run, which makes ordering simple: any unit with the same code fits, subject to the gearbox, drive type and sump.
Other cars with the same engine as the 323i
A replacement engine does not have to come from another 323i. These models left the factory with the same engine code, so a unit from any of them is a candidate donor once the sump, mounts and ancillaries are matched to your car.
M52B25: BMW E39 523i, BMW E46 323i.
How to confirm your engine code
The 323i only used the M52B25, but the exact version can still change with the build date, gearbox and market. Send us the last seven characters of the VIN and we read the engine code from BMW's records, or look for the code stamped on the block. How to find your BMW engine code.
Known 323i engine problems
The M52B25 in the 323i shares the known weak points of the M52 family. Full M52 guide.
| Known fault | What to check |
|---|---|
| Nikasil bore wear | A compression or leak-down test is the only reliable check; Alusil and iron-block units are not affected. |
| Cooling system | Look at the date of the last cooling refresh and check for a metal impeller. |
| VANOS seals and solenoids | Listen for a diesel-like rattle at idle and check for torque loss low down. |
| DISA valve (M52TU) | Remove the DISA valve and check the flap pin for play. |
| Crankcase ventilation | Look for oil in the intake and smoke on start. |
Nikasil bore wear. Early Nikasil engines run poorly when high-sulphur fuel damages the bore coating. Low compression and hard hot starts are the symptoms.
Cooling system. Plastic water pump impellers, thermostat housings and radiator necks crack.
VANOS seals and solenoids. Hardened seals cause rough idle and a loss of torque; double VANOS units also rattle.
DISA valve (M52TU). The flap inside the DISA valve can break and be drawn into the engine.
Crankcase ventilation. A blocked CCV causes oil consumption and leaks.
Symptoms to watch for on the 323i
Rattle for a few seconds after a cold start. The classic sign of a weak timing chain tensioner or stretched chain. It must be checked quickly: a chain that jumps a tooth can bend valves.
Poor low-down torque and uneven idle. VANOS seals or solenoids. The engine may run well at high revs but feel flat and lumpy at low speed.
Hard starting when warm and low compression. On engines with Nikasil bores, the bore coating may be damaged. A leak-down test confirms it.
Looking after the 323i engine
- Oil: 5W-30 or 5W-40 synthetic to BMW Longlife standard, about 6.5 litres with filter.
- Service interval: Oil every 10,000 to 15,000 km; VANOS seals and cooling every 100,000 km.
- Timing drive: Duplex lower and single upper chains at the front with hydraulic tensioner.
- Workshop notes: Ask whether the block is Nikasil or Alusil. Engines built from late 1998 use Alusil.
Buying a used engine for the 323i: checklist
- 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.
- 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.
- 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.
- Compression or leak-down figures. Even compression across all cylinders tells you more than mileage. Ask for the figures, not just a pass or fail, and compare the highest and lowest readings: a spread above 10 to 15 percent deserves a question.
- List of what is fitted. Engines are sold with different ancillaries: some have the turbo, injectors, manifolds, alternator and starter, others are long blocks. Agree the list in writing so you know which parts must come from your old engine.
- 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.
- VANOS operation. Rough idle, a rattle from the front of the head and a loss of torque at low revs point to VANOS seals or solenoids. These are serviceable parts and are easier to renew with the engine out.
- Bore coating. Early engines with Nikasil bores can be damaged by high-sulphur fuel. A compression or leak-down test is the only reliable check; units with Alusil or iron bores are not affected.
- Plastic cooling parts. Expansion tanks, thermostat housings and water pump impellers made of plastic crack with age. Plan to replace them when the engine is fitted.
BMW 323i replacement engine cost
We currently hold 6 323i engine engines. The cheapest is 1.413,00 €, the most expensive 3.099,00 €, and half of them cost less than 1.565,00 €.
Prices depend on the exact version, the donor's mileage, how complete the engine is and the demand for that code. Higher-output versions, low mileage and dressed engines with turbo, injectors and ancillaries cost more; long blocks and higher mileage cost less.
2 of these come from E36 donor cars, priced from 1.413,00 € to 3.099,00 €. An engine from the same body is the most direct swap because the sump, mounts and ancillaries already match.
On top of the engine, budget for the workshop's labour and the parts that are best replaced while the engine is out: engine mounts, the rear main seal, cooling parts, a clutch or converter seal, fluids and filters.
Replacement engines in stock for the 323i
These 323i units are in our Hamburg yard right now. Each listing shows real photographs of the engine you receive, its mileage and what is fitted.
BMW E36 325i M52B25 Engine 19971.413,00 €
BMW E39 523i M52B25 Complete Engine1.502,00 €BMW E36 323i M52B25 Engine, Premium Grade3.099,00 €
BMW E46 323i M52B25 Complete Engine1.565,00 €BMW E36 325i M52B25 Engine 1997 — 1.413,00 €, reduced from 2.000,00 €. It comes from a 1997 donor car, and 27 units are available. Ask the desk for compression figures or extra photographs before you order.
BMW E39 523i M52B25 Complete Engine — 1.502,00 €, reduced from 2.100,00 €. It comes from a recorded donor car, and 5 units are available. We can confirm fitment against your VIN the same day.
BMW E36 323i M52B25 Engine, Premium Grade — 3.099,00 €, reduced from 3.600,00 €. It comes from a recorded donor car, and 18 units are available. We can confirm fitment against your VIN the same day.
BMW E46 323i M52B25 Complete Engine — 1.565,00 €, reduced from 2.100,00 €. It comes from a recorded donor car, and 25 units are available. The listing shows every side of the engine and the fitted parts.
Will it fit my 323i?
Engine swaps and upgrades for the 323i
These engines were fitted to other versions of the E36 at the factory, which makes them the most practical upgrades: the body was designed around them and many parts are shared.
| Engine | Factory model | Power | Gain |
|---|---|---|---|
| M50B25 | E36 325i | 192 hp | +22 hp |
| M50TUB25 | E36 325i | 192 hp | +22 hp |
| M52B28 | E36 328i | 193 hp | +23 hp |
| S52B32 | E36 M3 US | 240 hp | +70 hp |
| S50B30US | E36 M3 | 240 hp | +70 hp |
Can I fit the M50B25 in my 323i?
Yes, it is one of the more common upgrades. Both are petrol inline-6 engines, so the mounting points are similar, but the M50B25 needs its own wiring and engine control unit, the matching gearbox or clutch, and often a different sump, cooling and exhaust. The gain is 22 hp and 0 Nm. In Germany and most of Europe an engine swap must be inspected and registered.
Can I fit the M50TUB25 in my 323i?
Yes, it is one of the more common upgrades. Both are petrol inline-6 engines, so the mounting points are similar, but the M50TUB25 needs its own wiring and engine control unit, the matching gearbox or clutch, and often a different sump, cooling and exhaust. The gain is 22 hp and 0 Nm. In Germany and most of Europe an engine swap must be inspected and registered.
Can I fit the M52B28 in my 323i?
Yes, it is one of the more common upgrades. Both are petrol inline-6 engines, so the mounting points are similar, but the M52B28 needs its own wiring and engine control unit, the matching gearbox or clutch, and often a different sump, cooling and exhaust. The gain is 23 hp and 35 Nm. In Germany and most of Europe an engine swap must be inspected and registered.
Fitting a replacement engine in the 323i
- Inspect or replace the timing chain parts. Look at the guides and tensioner. On high-mileage engines, replacing them now costs far less than doing it later.
- Reset VANOS adaptations. Clear the VANOS adaptations so the ECU learns the camshaft positions of the new engine.
- Fill with the right oil and prime it. Fill with new oil of the correct specification and a new filter. Crank with the fuel and ignition disabled until oil pressure builds.
- Coding and adaptations. On modern BMWs, the engine ECU must be matched to the car's immobiliser (CAS, FEM or BDC). Reset adaptations, register the battery and clear faults with diagnostic software.
- First start and leak check. Start the engine, let it idle and watch oil pressure, temperature and fault codes. Check for leaks and bleed the cooling system.
- First 1,000 km. Drive gently for the first few hundred kilometres, vary the engine speed and avoid full load. Change the oil and filter after about 1,000 km to remove any assembly debris.
The full fitting and first-start procedure.
323i engine questions
How much is a replacement M52B25 engine for a BMW E46 323i?
A used M52B25 for the BMW E46 323i costs from about 1.250 € to 2.100 € 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 M52B25 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 M52 Engines · Search M52B25 in the shop
How much is a replacement M52B25 engine for a BMW E36 323i?
A used M52B25 for the BMW E36 323i costs from about 1.250 € to 2.100 € 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 M52B25 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 M52 Engines · Search M52B25 in the shop
Will the M52B25 engine fit my BMW E46 323i?
Yes, if your BMW E46 323i was built with the M52B25. BMW used this 2.5 liter (2,494 cc) petrol engine with 125 kW (170 HP) in the E46 323i from about 1995 to 2000.
In our records the M52B25 is the engine for the E46 323i, which makes the match simple. Still, check the code on your old engine or send us your VIN.
Also tell us if your E46 has a manual or an automatic gearbox. The flywheel or the flex plate and some sensors depend on it.
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 M52 Engines · Search M52B25 in the shop
What should I replace when I fit a used M52B25 engine?
A used engine lasts longest when it starts life in your car with fresh fluids and new seals. Fit a new oil filter and fresh oil of the grade BMW lists for this engine, and refill the coolant with the correct BMW antifreeze mix. Check the spark plugs and the ignition coils, and make sure the fuel lines are clean and tight before you crank the engine. Change the drive belt, the thermostat and the water pump seals if they look tired, because they are cheap while the engine is out.
Look at the engine mounts and the clutch or the torque converter while the engine is out. Old mounts can crack a new engine's brackets, and a worn clutch is much easier to change now.
Before the first start, turn the engine over without fuel until the oil pressure light goes out. Then let it idle, check for leaks, and drive gently for the first few hundred kilometres.
The warranty asks for fitting by a qualified mechanic and the correct oil, coolant and filters. Keep your receipts in case you ever need to make a claim.
See all M52 Engines · Search M52B25 in the shop
How long does delivery of an M52B25 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 M52 Engines · Search M52B25 in the shop
How do I know a used M52B25 engine is in good shape?
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. An inspection certificate for the unit can travel with the order when you ask for it.
When you look at a listing, check the recorded mileage, the year and the photos of the ports and the stamp. Ask for photos of anything you want to see closer. If you want more photos or a short video of a unit, ask the desk and we send them before you pay.
On a petrol engine like the M52B25, a careful fitter will also look at the spark plugs, the coils and the timing side before the engine goes in.
If the engine fails inside under normal use, the warranty covers you. 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.
See all M52 Engines · Search M52B25 in the shop
How much is a replacement M52B25 engine for a BMW E36 323i?
A used M52B25 for the BMW E36 323i costs from about 1.250 € to 2.100 € 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 M52B25 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 M52 Engines · Search M52B25 in the shop
Is the BMW M52B25 a diesel or petrol engine?
The M52B25 is a petrol engine. It is a 2.5 liter (2,494 cc) inline 6, DOHC, 24 valve unit with no turbo (naturally aspirated), and it was built to the Euro 2 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 M52 Engines · Search M52B25 in the shop
What is the BMW M52B25 engine?
The BMW M52B25 is a 2.5 liter (2,494 cc) petrol engine from the M52 family. It has an inline 6, DOHC, 24 valve layout with no turbo (naturally aspirated), and makes 125 kW (170 HP) with 245 Nm of torque. BMW built it from 1995 to 2000 and it meets the Euro 2 emission standard.
You find the M52B25 in the BMW E36 323i, BMW E39 523i and BMW E46 323i. What we list: BMW M52 petrol engines for E36, E39, E46 and Z3.
At Autowerke Engines every M52B25 is a real used engine from our yard in Hamburg. Before a unit is listed, the yard checks the engine code against the listing, writes down the parts fitted to it, seals every opening and photographs the real engine you will receive. Each listing shows the year, the mileage and the price, so you can compare units side by side.
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 M52 Engines · Search M52B25 in the shop
How much is a replacement M52B25 engine for a BMW E39 523i?
A used M52B25 for the BMW E39 523i costs from about 1.250 € to 2.100 € 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 M52B25 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 M52 Engines · Search M52B25 in the shop
Delivery, warranty and payment
Before a 323i engine 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.
Door-to-door delivery is included to the address you give at checkout. Typical delivery takes three to five working days within Germany and neighbouring countries and five to ten working days to the rest of Europe and the UK.
Every engine carries a 12-month warranty on eligible internal failure when a qualified workshop fits it with new fluids and filters. Payment is by card, bank transfer or crypto; your invoice is emailed as soon as you order.
