BMW N62 / N63 engine: faults and reliability

• N62B36 3.6 naturally aspirated 272 hp (735i, 2001-2005)

  2001–2005 · 272 hp · N62B36

  With caution

  It is the oldest N62 and the 6 Series guide places coolant loss mainly on the older examples; check the hoses and level before buying.^[1][4]

• N62B40 4.0 naturally aspirated 306 hp (540i and 740i, 2005-2010)

  2005–2010 · 306 hp · N62B40

  With caution

  The open sources give no reliability data specific to the 4.0; it shares with the rest of the N62 the points to check (coolant hoses and valve stem seals).^[1][5]

• N62B44 4.4 naturally aspirated 320-333 hp (545i, 645Ci, 745i, X5 4.4i; 2001-2006)

  2001–2006 · 320–333 hp · N62B44

  With caution

  A 100,000 km test of a 745i recorded no engine defects, but the sources cite coolant loss from hoses (Gebrauchtwagenberater and Auto Bild) and, to a lesser extent, valve stem seals (Auto Bild): both points need checking.^[1][5][9]

• N62B48 4.8 naturally aspirated 360 hp (X5 4.8is, 2004-2006)

  2004–2006 · 360 hp · N62B48

  With caution

  Gebrauchtwagenberater calls coolant loss from cracked hoses a typical N62 problem on the X5 E53.^[10]

• N62B48TU 4.8 naturally aspirated 355-367 hp (550i, 650i, 750i, X5 4.8i; 2005-2010)

  2005–2010 · 355–367 hp · N62B48, N62B48TU

  Buy

  The German guides describe the 6 Series N62 as a solid engine and the X5 E70 4.8i's as an engine with few problems; even so, at over 15 years old, the coolant hoses and valve stem seals should be checked.^[2][4]

• N63B44O0 4.4 twin-turbo 408 hp (2008-2014)

  2008–2014 · 408 hp · N63B44O0, N63B44

  Avoid

  Gebrauchtwagenberater advises against the 550i with this N63 because of oil consumption (valve stem seals) and the stretched chain, and recommends a car built after July 2013; fiches-auto describes it as the big weak point of the petrol range.^[3][11]

• N63B44O1 (N63TU) 4.4 twin-turbo 450 hp (2013-2019)

  2013–2019 · 450 hp · N63B44O1, N63TU

  With caution

  Gebrauchtwagenberater considers it more reliable than the pre-July 2013 N63, but classes it as "to be checked" and still describes it as a complex engine.^[3]

Buy: No known serious faults, or they have already been corrected, in this version. With caution: Worth buying if something specific is verified: history, a replaced part or a completed campaign. Avoid: High risk of a serious fault that is hard to check for or prevent.

1. 1High severityFrequency: CommonLubricationN63 oil consumption from worn valve stem sealsYes: the original N63 is known for using oil and the German press attributes it to worn valve stem seals. Gebrauchtwagenberater gives €3,000-4,500 as a repair reference in Germany.
2. 2Critical severityFrequency: OccasionalTimingN63 timing chain stretch and guide breakageOn the N63 the timing chain can stretch and the sliding guide can break, leaving plastic debris in the sump and risking serious engine damage. We have found no European recall for this reason.
3. 3Critical severityFrequency: OccasionalTurboAdditional turbo coolant pump with a risk of short circuit and fireIn 2011 BMW recalled 5, 6 and 7 Series, X5 and X6 models built between 2007 and 2011 because of the additional turbo coolant pump: moisture, a short circuit and, in extreme cases, a fire. In 2012 there was another campaign for a crack in the pump, with a more robust version.
4. 4Medium severityFrequency: CommonCoolingN63 coolant loss and cracks in the cylinder headThe N63 loses coolant fairly often: Gebrauchtwagenberater cites it on the 550i, the X5 50i and others, along with cracks in the spark plug well. Owner reports add hoses and the water pump.
5. 5Medium severityFrequency: CommonCoolingN62 coolant loss from hoses and the pipe between the cylinder banksOn the N62 V8, coolant loss from cracked hoses or pipes is typical, especially on the earliest units. Replacing them is laborious: the hose between the banks means removing a good part of the engine.
6. 6Medium severityFrequency: OccasionalLubricationN62 blue smoke and oil consumption from hardened valve stem sealsOn the N62 V8, the valve stem seals can harden with age and cause oil consumption with blue smoke. It is not a widespread fault: several German guides describe the engine as solid.

Severity colours: low, medium, high, critical. How we rate them

Manufacturer

BMW

Family

N62 / N63

Fuel

Petrol

Displacement

—

Cylinders

8

Fuel system

—

Injection

—

Timing

Chain

Power

272–450 hp

Peak torque

650 Nm

Production

since 2001

Makes

BMW

Technical data^[3][6][7][8]

1. 2001–2005

   N62B36 3.6 naturally aspirated 272 hp (735i, 2001-2005)

   First version of the N62, 3.6 litres and 272 hp (200 kW), fitted to the 7 Series E65 (735i and 735Li). German Wikipedia limits the 735i to 2001-2003 and the English one extends it to 2005.^[6][8]

2. 2001–2006

   N62B44 4.4 naturally aspirated 320-333 hp (545i, 645Ci, 745i, X5 4.4i; 2001-2006)

   4.4-litre version: 333 hp (245 kW) in the 745i, 545i and 645Ci, and 320 hp (235 kW) in the X5 4.4i. The start years differ between sources: the 745i starts in 2001 (English Wikipedia) or in 2002 (German) and the X5 4.4i in 2003 or in 2004.^[6][8]

3. 2004–2006

   N62B48 4.8 naturally aspirated 360 hp (X5 4.8is, 2004-2006)

   4.8-litre, 360 hp (265 kW) version of the X5 E53 4.8is, prior to the TU revision of the N62.^[6][8]

4. 2005–2010

   N62B40 4.0 naturally aspirated 306 hp (540i and 740i, 2005-2010)

   4.0-litre, 306 hp (225 kW) version that replaced the 3.6 in the 7 Series (740i and 740Li, 2005-2008) and was fitted to the 5 Series 540i, which according to German Wikipedia was only sold in Europe.^[6][8]

5. 2005–2010

   N62B48TU 4.8 naturally aspirated 355-367 hp (550i, 650i, 750i, X5 4.8i; 2005-2010)

   Revised (TU) 4.8-litre version: 367 hp (270 kW) in the 550i, 650i and 750i, and 355 hp (261 kW) in the X5 E70 4.8i. Gebrauchtwagenberater places the arrival of the N62TÜ in July 2005.^[2][4][6][8]

6. 2008–2014

   N63B44O0 4.4 twin-turbo 408 hp (2008-2014)

   First version of the 4.4-litre twin-turbo V8: 408 hp (300 kW) and 600 Nm. It debuted in 2008 in the X6 xDrive50i and moved to the 750i, 550i, 650i and X5 50i.^[2][7]

7. 2013–2019

   N63B44O1 (N63TU) 4.4 twin-turbo 450 hp (2013-2019)

   Technical revision of the N63 (N63TU, 2012 update) with 450 hp (331 kW) and 650 Nm, fitted to the 750i, 550i, 650i and the X5 and X6 50i. Gebrauchtwagenberater places its arrival in the 5 Series in July 2013.^[3][7]