BMW N62 V8 Engine

BMW N62 V8 engine

N62 Valvetronic V8 engine.

Chronology

In 2002 the M62 V8 was replaced by the N62. The old engine was BMWs first V8 since the 1950s are had been in production for just over ten years. The new N62 incorporated many technological advances such as the Valvetronic system. The design goals included more power and torque with a better spread, better acoustics (quieter), better economy with lower emissions.

Initially the engine was available in 3.6 and 4.4 capacities however the 3.6 was only available in the E65 735i (the 335i and 535i were N54 3.0 turbos). The 4.4 was offered in the E60 five series 545i, six series 645i, X5 and the E65 745i. Quite a few external companies, such as Morgan, sold it in small volume cars.

In 2005 4.0 and 4.8 litre versions replaced their smaller predecessors with more powerful new offerings. The 4.8 was marketed as a five litre in the 550i, 650i and 750i (which used to be an M73 V12).

BMW N62 V8 engine

N62 V8 in a 650i coupe.

Design

The M62 had been a four valve per cylinder design with an alloy block, in BMW terms it was a modern engine. The N62 took the technology forward by using Valvetronic valve lift control in place of a throttle body, this improved economy and responsiveness. It also used VANOS on both camshafts rather than just the intake. It needs a vacuum pump as the lack of a normal throttle plate inhibits intake manifold vacuum creation.

The timing chain design was of a similar to the N73 V12 with one chain for each bank of cylinders driving both camshafts on that side, radically different to the M62. The oil pump is chain driven from the crankshaft. Most version had a cast crankshaft but a stronger forged unit was needed for the 4.8.

For the new engine BMW ensured more commonality with the V12 than had been the case with the older engines. The block used the same cylinder liners and spacings. There was a much higher sharing of parts than had been possible between the M60 and M70.

This was BMWs only V engine to have the DISA variable length intake technology, it wasn't deemed to be of benefit to the larger V12. The runner lengths were changed progressively from 3500rpm.

Like many of BMW's more modern engines a secondary air pump was needed to reduce emissions in the warm up phase, this wasn't fitted to the 4.8. The catalytic converter now had a pre-cat to improve the efficiency of the main unit. These were housed very close to the exhaust ports so as to warm up more quickly.

In 2005 a Technical Update version of the 4.0 and 4.8 was released which resulted in a small power boost. Both models now had forged crankshafts (previously only the 4.8 had) and the air intake was enlarged. The variable length DISA system was replaced by a two stage system and the intake manifold was now plastic instead of magnesium alloy. The 4.0 no longer had a secondary air system.

BMW N62 V8 engine

N62 internals showing Valvetronic actuators.

Variants

Code Size Power
bhp@rpm
Torque
lb/ft@rpm
BHP/
litre
Torque/
litre
Made Bore x
Stroke
Timing Weight
(kg)
VANOS
N62 3.6

4.0

4.4

4.8

272 @ 6200

306 @ 6300

319 / 333 @ 6100

360 / 367 @ 6300

266 @ 3700

288 @ 3500

325 / 332 @ 3700

369 / 361 @ 3400

76

77

74

75

74

72

75

76

2002-10 84x81.2

87x84.1

92x82.7

93x88

Chain 265 Valvetronic

Dual VANOS

 

BMW N62 V8 engine

N62 V8 in an E60 550i.

Problems

This was not a direct injection engine so didn't suffer from the associated problems.

The oil pump's check valve can come adrift and end up in the oil filter housing, BMW had a TSB (technical service bulletin) in regards to this. Lots of work to fix. It's very easy to remove the oil filter and check for this if buying a used car.

If there's a small coolant leak from the timing cover it's bad news. It's just a faulty seal but can take up to 60 hours of labour to change! There are third party solutions involving a new coolant pipe which can be fitted in under ten hours.

If the car smokes white once warmed up (cold is normal) and idling for a long time you have worn valve seals. The new seals are a much better design so if buying a used car see if they're been fitted. New ones can be fitted without removing the heads if the correct procedure is followed but it's still not cheap.

The oil separator / CCV valves clog up resulting is high oil consumption, common BMW problem.

The early style continuously variable DISA (3.6 and 4.4) can gum up with oil sludge.

If an engine sounds very clattery it can be due to air in the hydraulic valve lifters. This can happen if the oil level falls very low or the car is used for nothing but very short trips, I've seen it once. The solution is to bleed the lifters. Warm the engine up with a short drive then with the car stationary run the engine at 3500rpm for three minutes, this can be tried several times back to back if needed. Certainly worked for me.