BMW N47 Rebuild, common faults & everything you need to know
A complete guide to BMW's widespread 2.0 diesel - a common-rail inline-four with DOHC and 16 valves, a single VGT turbo (sequential twin-turbo on the N47S) and the notorious rear timing chain. From the rear timing chain, injectors and EGR/DPF to 200 hp builds, with factory-verified torque specs from BMW TIS and workshop pricing.
We have built and rebuilt BMW turbodiesels for decades. The N47 is the diesel engine found in everything from the 1 Series and 3 Series to the 5 Series, X1 and X3. It is a common-rail inline-four with DOHC, 16 valves and an aluminium block with cast-iron liners, force-fed by a VGT turbo (sequential twin-turbo on the strong N47S variants). The bottom end is robust, but the N47 has one defect that defines the engine: the rear timing chain. The chain, guide rails and tensioner sit against the flywheel side and wear prematurely, especially on early model years. When they start to rattle, the engine and gearbox must be separated to reach them. The N47 is also an interference engine, so a timing chain failure bends the valves. Beyond the chain, the injectors and turbo wear and the EGR/DPF clog with soot. We do everything from cylinder head reconditioning and turbo reconditioning to complete engine reconditioning with our own machine shop and a 12-month warranty.
The N47 at a glance
Shared base data for the N47 family (N47D20 2.0L and the architecture-sharing N47D16 1.6L). Variant-specific power and torque figures are listed in the table below. Torque values read from BMW's factory manual (BMW TIS tightening torques, edition 12/2007, for the E90 320d N47 and E82 120d N47) and cross-verified against the factory-page evidence images.
| Variant (code) | Forced induction | Power | Torque | Year |
|---|---|---|---|---|
| N47D16 (70 kW) | Single VGT | 95 hk | 235 Nm | 2013-2015 |
| N47D20 (85 kW) | Single VGT | 116 hk | 260 Nm | 2009-2015 |
| N47D20 (105 kW) | Single VGT | 143 hk | 300 Nm | 2007-2013 |
| N47D20 (120 kW) | Single VGT | 163 hk | 340 Nm | 2009-2014 |
| N47D20 (130 kW) | Single VGT | 177 hk | 350 Nm | 2007-2013 |
| N47D20 (135 kW) | Single VGT | 184 hk | 380 Nm | 2010-2015 |
| N47D20T0 N47S | Twin-turbo (sequential) | 204 hk | 400 Nm | 2007-2012 |
| N47D20T1 N47S | Twin-turbo (sequential) | 218 hk | 450 Nm | 2011-2015 |
The power and torque figures above are identity data (the engine's output per code, not tightening torques), compiled from BMW's variant lists and spec databases. Use them to identify the correct engine variant - the exact values are on the engine's data plate. N47S (T0/T1) is the sequential twin-turbo family (123d/125d/325d among others).
Torque specs
Read from BMW's factory manual (BMW TIS tightening torques, edition 12/2007, section 11/13 for the E90 320d N47 SAL and E82 120d N47 Coupe) and cross-verified against the factory-page evidence images. Stretch bolts (cylinder head, mains, connecting rod, vibration damper hub) are angle-tightened - always fit new ones. The cylinder head on the N47 is tightened with a jointing sequence: torque to value, slacken, retorque to a lower value and angle. Always work against the correct engine code.
Cylinder head & valvetrain
Engine block & bottom end
Fuel system (common-rail diesel)
Intake, exhaust & turbo
Note - Stretch bolts: cylinder head, main bearing, connecting rod and vibration damper hub bolts are angle-tightened stretch bolts (TTY). BMW specifies new bolts, and Meksta always fits new bolts on disassembly. The reason: stress accumulation is invisible and the cost of new bolts is negligible against the risk of failure. The cylinder head is tightened with a jointing sequence (70 Nm, slacken all at least 180 degrees, retorque to 50 Nm, then + 120 degrees + 120 degrees) in a diagonal order from the centre outwards.
NOTE - Rear timing chain: The N47 has a single timing chain and it sits at the rear, against the flywheel and gearbox side. The factory-verified chain torques (upper chain tensioner M22x1.5 = 70 Nm, lower tensioner = 10 Nm, guide rail bearing pin = 20 Nm) all belong to the rear chain system. Because the engine is an interference engine, a chain failure bends the valves. Reaching the chain requires separating the engine and gearbox, which is an extensive job - we replace the entire chain kit with rails, tensioners and sprockets in one go.
NOTE - Two separate bolted joints at the rear: the upper timing chain tensioner (70 Nm, M22x1.5) must not be confused with the lower tensioner (10 Nm, M6) or with the guide rail bearing pin (20 Nm, M16x1.5). These are three different fasteners in the same rear chain system with different torques. Likewise, the flywheel bolts (120 Nm) are a different group from the reluctor ring bolts (5,0 Nm + 45 degrees) at the crankshaft end.
NOTE - Diesel, no spark plugs: The N47 is a common-rail compression-ignition diesel - it has glow plugs for cold starting, not spark plugs, and individual injectors per cylinder. The injector clamp is tightened in two stages (8 Nm then 26 Nm), the high-pressure line nuts to 24 Nm and the rail pressure sensor to 70 Nm. During cylinder head work we check and replace glow plugs and seal/adjust the injectors as needed.
NOTE - Values we do not publish: we only publish torque values that we have been able to verify against an actual factory page. The glow plug torque does not appear on any published TIS page for the N47 (BMW only lists a preheating relay) and is therefore deliberately omitted - we ignore the common forum value. Likewise, the exhaust manifold torque to the cylinder head is uncertain for the N47: TIS page 11 62 does not name the N47 unambiguously (the N47 has an integrated, cast exhaust manifold), so we rely on the documented turbo-to-manifold value (25 Nm) instead. We never guess and never borrow another engine's value. Ask us for them if you need them and we will look them up in the correct factory manual.
NOTE - N47 vs N47S (twin-turbo): turbo-to-manifold is 25 Nm on the single-turbo N47 and on the low-pressure stage of the sequential twin-turbo N47S. The N47S high-pressure turbo, however, has its own torque (8 Nm) - never mix them up. Always work against the correct variant.
Factory tolerances (bearing clearance, deck height, piston clearance) for the N47 are documented separately and published once cross-verified. Every measurement is checked against factory tolerances with our own machine shop.
Common problems on the BMW N47
This is what we see most often when an N47 comes in. Symptoms, causes and how we fix them.
Rear timing chain failure
Notorious N47 fault • Critical- Symptoms
- A rattling or clattering noise from the rear of the engine (towards the bulkhead/gearbox), especially on cold start and at idle, fault codes for camshaft versus crankshaft position and, in the worst case, the engine jumping and dying. Because the N47 is an interference engine, the result is bent valves and sometimes damaged pistons.
- Cause
- The N47's single timing chain sits at the rear against the flywheel side. Early chains, guide rails and tensioners wear prematurely, especially on model years around 2007-2011. Because the chain sits at the back, the engine and gearbox must be separated to reach it. We replace the entire chain kit with rails, tensioners and sprockets.
Clogged EGR, DPF & sooty intake
Very common • High- Symptoms
- Power loss, rough idle, black smoke, limp mode, frequent regeneration or a clogged particulate filter, fault codes for EGR or boost pressure and increased fuel consumption.
- Cause
- The EGR system recirculates exhaust gas which, together with oil mist from the crankcase ventilation, builds soot deposits in the EGR valve, intake manifold and ports, and loads the DPF. Common on all N47s and especially on short trips and city driving.
Worn common-rail injectors
High mileage • High- Symptoms
- Stalling, a knocking diesel noise, white or black smoke, hard starting, rough running and an injection fault code. Often a single cylinder that misfires or has an abnormal quantity correction.
- Cause
- The Bosch common-rail injectors (solenoid or piezo depending on variant) wear and start to leak or deliver the wrong quantity. Poor fuel and neglected filter changes accelerate the wear. Requires testing, coding, reconditioning or replacement of the injectors.
Turbo wear & sticking VGT mechanism
High mileage • High- Symptoms
- Lost boost, limp mode, a whistling or howling noise, blue smoke under load and a boost pressure fault code (underboost or overboost). On the N47S the transition between the two turbos can become uneven.
- Cause
- The VGT turbo's variable vanes seize with soot, and the thrust bearings wear at high mileage. The oil feed is sensitive to neglected oil changes. On the N47S twin-turbo the control and actuator for the low-pressure/high-pressure stage can play up. We recondition the turbo or replace it as part of the overhaul.
Broken swirl flaps in the intake
Certain variants • Medium- Symptoms
- Rough running, power loss, a fault code for the intake flap and, in the worst case, a broken flap arm or bush being drawn into a cylinder.
- Cause
- The intake manifold's swirl flaps and their actuator wear and break off after soot build-up. We replace or professionally blank them off, clean the intake and code them out where needed.
Rod & main bearing wear
High mileage • Critical- Symptoms
- A knocking noise from the lower engine under load, low oil pressure, metal shavings at the oil change and, in the worst case, engine failure.
- Cause
- The main and rod bearings wear after high mileage, oil starvation, neglected oil changes or hard boost. Requires crankshaft grinding, new bearings and inspection of the cylinder bores. We check everything against factory tolerances.
BMW N47 rebuild pricing
Pricing based on N47 specifications: 4-cylinder inline, 84 mm bore, 16 valves, 5 main bearings + 4 rod bearings, aluminium block with cast-iron liners. We carry out cylinder boring, crankshaft grinding and cylinder head resurfacing with our own machine shop. The rear timing chain and turbo are handled separately. All prices exclude VAT and parts.
Cylinder head reconditioning
Bottom end
Full rebuild
Performance
Cylinder machining (4-cyl, 84 mm bore)
| Service | Price |
|---|---|
| Cylinder boring 4 cyl inline block (84 mm) | 3 318 kr |
| Plateau honing 4 cyl | 1 050 kr |
| Stress boring 4 cyl | 4 603 kr |
| O-ringing block 4 cyl (high-boost) | 2 800 kr |
| Deck decking block 4 cyl | 1 974 kr |
Crankshaft work (5 main + 4 big-end, 8 counterweights)
| Service | Price |
|---|---|
| Crankshaft grinding (5 main + 4 big-end) | 3 010 kr |
| Polishing standard | 1 022 kr |
| Cleaning 4-cyl crankshaft | 784 kr |
| Straightening (medium) | 1 190 kr |
| Camshaft journal grinding 4 pcs (DOHC) | 1 540 kr |
| Remove/fit counterweights 8 pcs | 2 044 kr |
Valve reconditioning (16 valves)
| Service | Price |
|---|---|
| Cutting 16 valve seats (standard) | 1 820 kr |
| Cutting 16 valve seats (large) | 2 772 kr |
| Valve guide replacement 16 pcs (light alloy) | 2 548 kr |
| Manufacture of valve seat inserts 16 pcs | 3 080 kr |
| Bronze sleeves fitting 16 pcs | 2 268 kr |
Resurfacing (I4, standard cylinder head size)
| Service | Price |
|---|---|
| Resurfacing cylinder head 4 cyl (standard) | 1 330 kr |
| Resurfacing cylinder head 4 cyl (large) | 1 596 kr |
| Resurfacing block 4 cyl (standard) | 1 988 kr |
| Resurfacing block 4 cyl (large) | 2 114 kr |
| Resurfacing manifold 4 cyl | 2 842 kr |
Con-rod work (4 pcs)
| Service | Price |
|---|---|
| Replace con-rod bush 4 pcs | 2 240 kr |
| Manufacture con-rod bush 4 pcs | 2 898 kr |
| Length adjustment con-rod 4 pcs | 2 898 kr |
| Replace press-fit piston 4 pcs | 1 582 kr |
| Replace piston ring 4 pcs | 1 106 kr |
| Resizing big-end housing 4 pcs | 2 352 kr |
| Check/straighten con-rod 4 pcs | 1 414 kr |
| Full reconditioning con-rod 4 pcs | 3 164 kr |
| Steel shot peening con-rods 4 pcs | 2 268 kr |
Pressure testing & balancing
| Service | Price |
|---|---|
| Pressure testing cylinder head 4 cyl (small) | 1 876 kr |
| Pressure testing cylinder head 4 cyl (large) | 2 800 kr |
| Pressure testing cylinder block | 1 400 kr /h |
| Balancing rotating assembly straight 4-cyl | 3 742 kr |
| Weight matching con-rods 4 pcs | 1 316 kr |
| Weight matching pistons 4 pcs | 1 092 kr |
| Flywheel balancing | 2 100 kr |
| Balancing flywheel + clutch | 2 842 kr |
Indicative pricing for the N47 configuration (4-cyl inline, 84 mm bore, 16 valves, alloy head, aluminium block with cast-iron liners). Labour prices exclude VAT and parts (piston rings, bearings, gaskets, stretch bolts, glow plugs, injectors, timing chain kit, turbo). Request a quote for an exact price after inspection.
Tuning the BMW N47
The N47 is a rewarding diesel to build torque on. The aluminium block with cast-iron liners and the bottom end take boost well, so big power and torque come from remapping, an upgraded turbo and injectors - but the timing chain and DPF/EGR must be kept in order first.
- 1
Remapping & intake/exhaust
A Stage 1 remap, a freer intake, a larger intercooler and a downpipe give a big gain in both power and torque thanks to the turbo. The bottom end handles this well with the right margins and a healthy timing chain.
180-210 hk - 2
Larger turbo / hybrid
An upgraded or hybrid VGT turbo with larger injectors and a Stage 2 remap. The stock bearings handle more boost with the right margins and turbo work.
220-250 hk - 3
Forged internals + large turbo
Forged pistons and con-rods, ARP bolts, balancing and a larger turbo. This opens the power window right up for a 2.0 diesel.
250-280 hk - 4
Full build
A complete bottom end, ported cylinder head, upgraded fuel system and large turbo for track and drag. We build the whole chain in-house with performance engine building.
280+ hk
Questions & answers about the BMW N47
What we hear most often from N47 owners.
What does it cost to rebuild a BMW N47?
A cylinder head reconditioning costs around 5 000 - 7 000 kr (labour), a complete engine reconditioning around 19 500 - 30 500 kr. On top of that come parts (gasket, bearings, piston rings, stretch bolts, glow plugs) and possibly a rear timing chain kit, injectors or turbo, typically 8 000 - 25 000 kr depending on condition and variant. We give a fixed quote after inspection.
Why does the timing chain fail on the N47, and why is it so expensive to replace?
The N47 has a single timing chain that sits at the rear against the flywheel and gearbox side. Early chains, guide rails and tensioners wear prematurely and start to rattle, especially on model years around 2007-2011. Because the chain sits at the back, the engine and gearbox must be separated to reach it, which makes the job extensive and expensive. If the chain fails, the valves hit the pistons because the N47 is an interference engine. We replace the entire chain kit with rails, tensioners and sprockets in one go.
Is the BMW N47 an interference engine?
Yes. The N47 is an interference engine with a timing chain. If the chain jumps or breaks, the valves hit the pistons, which bends the valves and often causes consequential damage. That is exactly why a timing chain failure on the N47 is so serious - a rattle from the rear must never be ignored.
Why does my N47 smoke and knock?
Black smoke and power loss are most often due to a clogged EGR/intake, a full DPF or a sticking VGT turbo. A knocking diesel noise and white smoke point to worn common-rail injectors. A knock from the lower engine under load can be rod or main bearing wear. We clean the intake and EGR, test and recondition/replace injectors, fix the turbo and check the bottom end against factory tolerances.
How long does a rebuilt N47 last?
With a proper rebuild and regular maintenance: 250 000 - 400 000 km or more. The bottom end is robust. What matters is that the rear timing chain is replaced and healthy, and that the EGR/DPF, injectors and turbo are kept in order. With that, the N47 is a durable diesel.
Can you tune an N47?
Yes. A Stage 1 remap often gives 180-210 hp on a 184 hp single-turbo variant with a solid increase in torque. With a bigger or hybrid turbo, upgraded injectors and Stage 2 you build 220-250 hp. With forged internals and a big turbo, 250-280 hp. The robust bottom end makes the N47 a good base for diesel builds - but a healthy timing chain and a sorted DPF/EGR are a prerequisite.
Should you rebuild or replace the engine?
For the N47: it depends on the damage. A used N47 has an unknown timing chain history and the same wear points (rear chain, injectors, turbo, EGR/DPF). A rebuilt engine has known tolerances, a new timing chain kit, new wear parts and a 12-month warranty. We ship worldwide.
See also: we recondition and build turbo engines and diesels from BMW and other manufacturers. Feel free to compare with BMW's inline-six BMW M54 or the VW Group diesel VW 1.9 TDI. If you only need the turbo sorted, we do that via our turbo reconditioning. See all our engine types.
Do you have an N47 that needs looking at?
Call us directly or send in a quote request. We reply within 24 hours.