BMW M60 and M62 V8 Engines

BMW M60 V8 engine

M60, the first BMW V8 since the 1950s.

Chronology

Since the mid-70s BMW's largest engine had been the M30 3.5 which put out 218bhp in it's Motronic injected form. Whilst this was one of BMW's legendary engines and was bullet proof in terms of reliability the fact was that more power was needed to compete with some of Mercedes newer offerings and the big V8s found in the USA. In 1988 BMW released the M70 5.0 V12, but it was expensive and not a realistic option for the five series. A 4.0 six was investigated (the E34 M5 S38 went up to 3.8) but not progressed with. So a new V8 was needed.

BMW had made V8s before in the 1950s for such cars as the 507 coupe and there had been an attempt in the 1970s but the 70's fuel crisis put and end to it. So the new engine would start with a clean slate. The projected in service date was 1986, but it took until 1992 for the M60 to emerge.

In 1992 3.0 and 4.0 V8s were sold in the E34 530i / 540i, E32 seven series and E31 840i. The automatic cars had a five speed box and the rare manuals a six speed box, both one more gear than with the M30. In the UK the M30 soldiered on in the E32 until the end, a 730i could be bought as an M30 six or a more expensive V8.

In 1996 the displacements rose to 3.5 and 4.4 litres and engine became the M62. The E38 730i became a 735i but confusingly the 740i was still called a 740i and the 840i also kept it's name.

The M62TU (technical update) was released in 1998 with little fanfare and with the same capacities. A new 4.6 was released for the X5 4.6is, a car with a prodigious thirst and seriously short range (as little as 240 miles) from it's large petrol tank.

Alpina made an M62TU 4.8 automatic Z8 as an alternative to the manual car which had the M5's engine. This sold very well in the USA.

BMW M62tu V8 engine

M62TU with VANOS on the intake camshafts.

Design

From the outset the M60 was an all alloy engine with Nikasil liners and a plastic intake manifold to keep weight down. In fact it weighed 30% less than the aborted 70's prototype. It was a 90 degree V8 with four valves per cylinder and didn't have VANOS. In order to allow room for growth the cylinder spacing was 98mm instead of the 91mm used on smaller engines. A cast crankshaft was used on the 3.0, forged on the 4.0.

The massively long double row timing chain drove only the intake camshafts. As was the practice on the M50 series the exhaust camshafts were linked to the intakes by a separate chain. Other M50 features included accessories which were driven by a serpentine belt and an oil filter which lived in an easily serviced canister. The whole package lived under a nicely sculpted cover on rubber mounts, it's real purpose was to absorb engine noise.

In order to comply with ever tighter emissions laws it was no longer desirable to simply recirculate crankcase gases into the intake. An oil separator valve (OSV) was designed to return oil to the sump and pass cleaner air back to the intake. It operated on a vortex principle and was used in most subsequent BMW engines.

The engine used hydraulic tappets to reduce maintenance and had balance weights designed into the camshafts to ensure smoother running. Knock sensors and the one coil per cylinder approach also featured. From the outset it used a low restriction MAF instead of a flap based air flow meter. This was a truly modern engine, there was doubt that it was the most advanced V8 in the world when it entered production.

A new manufacturing process was used for the conrods which connect the crankshaft to the pistons. Traditionally the big end caps were made separately and mated with perfectly flat surfaces. In the new design the conrod was made as one piece from sintered steel and snapped in two at the big end! This fractured surface fitted together perfectly and gave a better join.

But the new beast had a glass jaw, in markets with high sulphur fuel (which included the UK in the early 90s) the Nikasil cylinder liners could wear quickly. The M52 six has the same problem and BMW replaced many under warranty. The M62 changed over to Alusil liners which solved the problem.

In addition to increases in displacement the M62 had design goals of better economy, lower emissions, more torque and quieter running - although the M60 was already a very smooth engine. To this end BMW replaced the dual row timing chains with single. Whereas the M60 has used an idler sprocket above the crankshaft at the bottom of the V valley the new engine used a chain guide. They also fitted an electronically controlled thermostat which was to see service on the later M54.

M62s have a remotely mounted oil filter canister on the inner wing, a handy recognition feature.

For the final M62TU variant the major change was the fitting of VANOS variable valve timing to the intake camshafts. This results in more mid-range torque and very slightly better economy. This engine had an electronically operated EML throttle body and a non-return fuel rail.

BMW M60 V8 engine

M60 V8 in an E39 540i.

Variants

Code Size Power
bhp@rpm
Torque
lb/ft@rpm
BHP/
litre
Torque/
litre
Made Bore x
Stroke
Timing Weight
(kg)
VANOS
M60 3.0

4.0

218 @ 5800

286 @ 5800

229 @ 4500

295 @ 5100

72.7

71.5

76.3

73.8

April 92 - 96 84x67.6

89x80

Chain 146 No
M62 3.5

4.4

4.6

235 @ 5700

286 @ 5700

236 @ 4700

310 @ 3900

67

64

67.4

70.5

96 - 98 84x78.9

92x82.7

Chain 140 No
M62TU 3.5

4.4

4.6

241 @ 5800

292 @ 5400

342 @ 5700

254 @ 3800

325 @ 3600

354 @ 3700

69

65

74

73

72

79

98 - 2005 84x78.9

92x82.7

93x85

Chain 140 Single

 

BMW M62 V8 engine

Big 4.4 V8 in an E38 740i.

Problems

The oil pump bolts could sometimes back out and fall into the sump. Reassembly with a bit more threadlock is the answer.

The cooling system wasn't up to the standards of older versions. The radiator wasn't made of the best materials. In addition to overheating the fittings could snap off when worked on as the plastic became brittle with age. It's much more of a problem in hot countries where the system is under more strain. Regular coolant changes are vital.

On the M60 the Nikasil liners reacted with sulphur in petrol and wore badly, the only solution was a new block. In the UK we now have low sulphur fuel which we didn't have in the early 90s. So any car that runs OK now will likely stay that way.

The oil separator valve can foul up, especially if the car is used for a lot of short journeys in cold damp weather. Symptoms include poor running, excessive oil consumption and a whistling noise. It's not the easiest part to access. All tubes leading to and from it must be replaced or removed and throughly cleaned if fitting a new part.

Oil can leak past the valve cover gasket into the spark plug wells.

In the event of a lot of chain noise, especially when cold, it's worth fitting a new chain tensioner. It's an inexpensive and easily accessed part. It doesn't fail often in the this engine.

The VANOS units in the M62TU can become noisy as the oil seals wear. It's a big job to change them and they can soldier on for 10,000s of thousands of miles with the noise being the worst symptom. A thicker grade of oil can help but won't do your tappets any favours.

Knocking under acceleration can be a sign that one of the two catalytic converters had failed and is highly restrictive. The engine management system tries to cope with this but can't control each bank of injectors well enough, so one sign leans out and knocks. Not a common fault.

The four rubber and metal mounts which hold on the engine cover rot with age and fail. They used rubber to isolate engine noise, but not a good enough rubber.

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.