Timm's The BMW M60 M62 and M62TU
V8 Engine
Working on the BMW V8 engines - it's not as scary
as it first seems
Above is the M60 engine, the first of the modern BMW V8's, it
was sold as a 3-Litre (M60B30) and 4-Litre (M60B40)
History and development
M60
BMW introduced the M60 engine in 1992, fitted to the E32 730i and 740i.
It was sold alongside the M30 straight-six and the mighty M70 5-Litre V12
in the E32. It was a radical advancement on these engines as both the
M30 and M70 were standard 2-valve per cylinder, distributor-ignition
engines of traditional design - well, apart from the all electronic throttle
control on the V12 and some versions of the M30B35.
The M60 engines introduced 4-valves per cylinder, quad overhead cams,
coil-over-plug ignition which dispensed with the distributor and HT leads,
duplex timing chains, 10.5:1 compression, twin-walled exhaust manifolds
and cylinder walls hardened using the Nikasil process rather than using
the traditional liner. The new V8 produced more power per litre, but more
importantly it was more economical and produced less pollution. The
M60B30 was fitted to my first 7 Series and was a good introduction to this
great engine, I'm on my 7th BMW V8 now with the N62B46.
Mention the M60 engine, even today in 2018, and the next word will be
Nikasil. Nikasil was a process to harden the cylinder walls, rather than
using the traditional cylinder liner, the Nikasil process allowed the
machined aluminium bores to provide a bearing surface which promised
longevity and better sealing between cylinder and piston. Although the
Nikasil process had been used previously with no problems, the
combination of the M60 and fuels with high Sulphur levels softened the
cylinder walls. The resultant wear meant a loss of compression and as the
engine was designed without replaceable cylinder liners the engine was
effectively scrapped.
Although a great many M60's were re-fitted with a new short-block by
BMW, these were initially Nikasil blocks and could have failed again.
BMW's solution was to replace the Nikasil process with a new cylinder-
hardening process called Alusil. Around the same period, the Sulphur
levels in fuels was reduced and those engines that suffered bore wear
were replaced, and those that were not replaced were not affected once
the Sulphur levels decreased. As Nikasil deterioration resulted in
catastrophic engine problems due to bore failure there were no engines
that were affected but kept running for any length of time, and this
meant that the Nikasil failure period was limited. It has been many years
now since Nikasil failure was a worry with the M60 engine - further
details can be found here.
It might have been expected that the 730i V8 (218 BHP) would have
much better performance than the 730i I-6 (185 BHP), and the M30
engined E32 would be dropped - but this was not the case as BMW fitted
the V8 models with a 3.23 differential whereas the I-6 730i got the much
shorter 4.1. The result was that the V8 had the same 0-60 MPH
performance as the I-6 and most owners of the 730i were not that
interested that the V8 was 5 MPG more frugal.
M62
If the M60 had a shortcoming it was the lack of torque at low revs,
especially the 3 Litre M60B30 which really only got going at 4000 RPM.
The long final drive ratio certainly didn't help, especially since the part-
throttle gear-changes were made well below the power-band. To address
the lack of performance at low revs the M62 was introduced in 1995.
The M62B44 fitted to the 840ci, the long cable across the front of the engine is for cruise
control
The M62TUB44 fitted to the E38 - The CC, ASC and throttle cables have been replaced with EML
The M62 was produced as the 3.5 Litre M62B35 and the 4.4 Litre M62B44
and fitted to the E31 and E38. The published power for the 4.4 Litre M62
was 286 BHP (sometimes quoted as 282 BHP) which is the same figure as
quoted for the 4 Litre M60. Again, BMW changed the differential from 3.15
to 2.93 when the M62 was introduced (except for the Sport 740i which
retained the 3.15) and the acceleration figures again remained the same.
The same differential ratio change was present on the 8-Series 840ci.
When the M62 was introduced in the E31, the rear axle ratio changed from
2.93 (M60) to 2.81 (M62) - and still the same acceleration figures were
stated. Mechanically the M62 lost a couple of useful parts, the duplex
timing chains and the idler sprocket, in their place was added a single
timing chain and plastic chain guides. In performance terms, the M62
produced a hefty amount of torque at lower revs and the more
sophisticated DME 5.2 engine management increased fuel economy.
However, the improvements didn't really make that much difference,
especially with the longer final drive, and it wasn't until the M62TUB was
introduced that the performance targets were realised. The DME 5.2
engine management added a lot tighter control of the engine and the
diagnostic capabilities were increased drastically.
M62TUB
The M62TUB44 is really the engine that the M60 aspired to be, it has
heaps of low-down torque, is economical and produces much lower
emissions. The main difference was the introduction of variable valve
timing on the inlet camshafts (Vanos), this was the source of the flatter
torque-curve and the better fuel economy.
The M62TUB also introduced fully-electronic throttle control (EML), this
meant that the ASC and cruise-control actuators were not required, but
more importantly, it meant that the throttle response could be altered
depending on driving style. The relation between throttle pedal and
throttle butterfly were not fixed as it is when a cable is used, instead the
throttle butterfly could open by different amounts and at different speeds
with the same pedal press depending on driving mode.
This gives the 740i and 540i with the M62TUB44 better performance at all
engine speeds. Perversely, the published acceleration remained the same
as did the BHP, owners who have driven both versions would disagree. The
added complexity also increased the problems with the V8 with the
introduction of 'Vanos noise' (which wasn't terminal although annoying)
and failure of the timing solenoids and seals.
Engine details:
More information on all three versions of the V8 can be found below:
M60
M62
M62TUB
Problems with the modern V8:
The M60/M62/M62TUB engines have proved exceptionally reliable - there
are many thousands of the Nikasil M60's still in daily use, maintaining
perfect compression. After a shaky start the modern BMW V8's have
proved to be an unrivalled success. However, they have a few weak spots,
the most common are listed below:
•
The cooling system overheats and explodes
•
The crankcase ventilation system causes all sorts of problems
•
The valve train makes some scary noises
•
The M62TUB44 can suffer from 'Engine Failsafe' problems
•
The M60 could easily over-fuel and fail to start for days
•
Vacuum leaks causes strange behaviour
Click on the links below for more information and repair instructions:
SEARCH MEEKNET
SEARCH MEEKNET