Buying a BMW 8-Series is a worrying prospect, there are so many stories of them being a money-pit, really difficult to repair, a car only suitable for a collector with deep pockets. However, they are also described as an 'appreciating classic'. Well, neither statement is really true, they are no more expensive to repair than the E32 and a lot easier than the E38. The E31 V8's haven't appreciated in value yet (2015), possibly in the future. There are some V8's holding their prices but these are very late Individual Sport models with extremely low miles, well out of my price range. The early 850i prices (all that is available in the UK unless they are imported) are pretty static, even the 850csi's (although much more expensive) don't seem to be moving.
Models available in the UK
There were only 3,040 E31's built for the UK, 2190 of those were V8's and 697 fitted with the M70 V12, the remainder being 153 850csi's. The UK never received the 850ci fitted with the M73 engine although a few have been imported. This means that you will find a few 850i V12's for sale with most of these being 1991 - 1993 models, the rest will be the 4.0Ltr M60 powered 840i and the 4.4Ltr M62 powered 840ci.
A close look at an E31 8-Series
When I started looking for an 8-Series I didn't have a clue what was available, what the cockpit looked like or what options you could get. So, to start with, here are a few pictures with short descriptions:
The Canyon Red 840ci to the right has the standard quad-pipes fitted. It also has the standard 17" alloys (radial styling No 5), these are not staggered (the fronts are as wide as the rears) and are usually fitted with 235/45 tyres. These are three-part with a separate centre cap, inner and outer castings which are bolted together with 34 fixings. They are great-looking but need regular restoring due to corrosion.
The front view of an E31 is just perfect, a really timeless design. The grille's are small, like those on the M1. Outside of the grilles are two slatted mouldings, these generally fade or drop off. The clips that hold them on often fail when they are removed, which is needed to access the light assembly. The light assembly contains (from centre outwards):The main beam units, side lights and indicators. The main-beams (on the UK models) are used when the flasher-stalk is pulled and when the main-beams are switched on.
The non-Sport model to the right still has a pretty-low front spoiler, but at least it clears a standard-height kerb. As from the rear, the spoiler and the mirrors are the only visual differences between the Sport and non-Sport models.
The Sport bodywork does not make the 840ci any faster in a straight-line, in fact, it has more drag. What it does give is down-force which plants the car confidently at speed.
It's not a proper sports car unless the lights pop-up - and they do! The UK models have projector lenses for the dipped-beams and the fog lights. In the pop-up pods (from outside to inside), are the dipped-beams, fogs and main-beams. Below are the secondary main-beams and side-lights. With eight 55W bulbs running at the same time there is no shortage of light. Of all the BMW's I've owned, the E31 has the best headlights, even better than the Xenon's fitted to my younger E38. Xenon systems are often retro-fitted, but usually in the world regions that did not have projector lenses fitted. The USA models, for instance, have plain reflectors.
The cockpit of the E31 is stunning. This is a 1999 840ci Sport Individual which means it is fitted with the Steptronic gearbox. This allows full automatic control of the gearbox, or, when the selector is pushed to the left, manual control. In the manual mode, the gearbox can be controlled sequentially by pushing the selector forward (the select a higher gear), or backwards (to select a lower gear). The software will not allow gear-changes that would damage the drive-train. This car has the Becker Nav system and a 3-spoke wheel retrofitted
The MID displays useful information such as fuel consumption and outside temperature. It also displays warning messages such as brake-pad wear.
Around the gear selector panel are a number of switches and indicators. On the left-hand side is the alarm indicator and the passenger heated-seat control. This has two heating levels. If the high level is selected, the setting will be reduced to low once the seat is up to temperature.
To the right of the selector is the ASC button (Automatic Stability Control) and the drivers heated-seat control.
The picture near-right shows the most common equipment level - ASC control and the alarm indicator.
Far right is a well equipped panel (on an 850ci). The additional controls are for EDC (Electronic Damper Control) and a control for the rear blind.
This is the same wheel as was fitted in the E32's in late '93 and '94 and contains one of the first airbags to be used by BMW. Despite its looks, this wheel has good feel and visibility of the instruments.
Fortunately, there are many BMW steering wheels that are a direct fit that still contain the single-stage airbag.
The steering wheel shown to the right here is from an E36, and is a popular replacement on the E31. The method of replacing the wheel is shown on this website.
There are many other steering wheels that are a direct fit, and some can be simply modified. The only necessity is that the airbag is a single-stage unit, the later dual-stage bags will not operate correctly.
The steering wheel controls shown here are:
Below the wash-wipe is the cruise-control. This is the standard BMW system that allows +/-1 KPH adjustment of speed by pushing/pulling the control. Although the cruise control was standard in the USA, it is less common in the UK.
LHS: The upper control is the indicators/flash/high-beam/low-beam. Pressing the end of the stalk brings up the OBC (On-Board Computer) information on the Multi-Information-Display.
Below is the steering-wheel height and rake adjustment, this is part of the memory system which includes seat and mirror positions. The motorised steering-wheel height and rake adjustment was an option in the UK.
In real life, they are brilliant for children, they have a steep cant to the rear and will hold then safely in position. As long as the front seats are moved forward slightly, an adult can be comfortably seated, but it is a little claustrophobic as you are wedged-in, there are no doors and no window controls!
Although the lower centre bolster looks like a storage area, this is where the fuel tank crosses the transmission tunnel.
The upper centre bolster can be lowered to reveal the ski-boot hatch, it also contains a first-aid kit.
They have to provide this anchor and be able to tip forward to allow access to the rear seats. The seat has a chrome handle on the side member for this action.
The seat to the left here is the non-Sports seat, however, it has large bolsters to keep the driver secure during sharp changes in direction.
The seat below is the Sports seat, this has additional adjustment for thigh-support. The bolsters are slightly harder and larger than the standard seat. Both models have three memory settings via the buttons at the edge of the seat.
The seats have multiple adjustments via the two controls in the seat base. The large control adjusts seat-base height, tilt angle and forward/back. The smaller rear control adjusts the rake of the back.
The memory system consists of the seat position, mirror position and steering wheel settings (optional). There are three memory settings, activated by setting everything to the preferred position, pressing 'M' and then one of the numbered keys.
To the left is another common alloy styling for the E31, this is Style 5 which is another three-part alloy with a separate centre-cap and a two-piece rim. The rim is secured with 34 fixings. These are 17" and are usually fitted with 235/45 tyres. These also suffer from corrosion around the fixings but look spectacular when reconditioned.
This alloy is a 16" Turbine (Style 9) which is usually shod with 235/50 tyres. This is the least popular alloy and the only original alloy available on the E31 with a 16" diameter.
One popular upgrade is to fit M-Parallels which were standard fitment on the 850CSi (8J front and 9.5J rear). The price from BMW is quite high and you may find E31's fitted with replica M-Pars (as is the case with the 840ci Sport shown at the top of this guide).
The E31 above has the infamous Throwing Star alloys fitted (Style 21M). These are the alloys most associated with the E31. They are also fitted to the M5, but the latter has a larger bore and are not staggered. Those fitted to the E31 have an 8J front and 9J rear and are 17". The offsets are unusual for a BMW (10F 19R).
The alloys are three piece, the throwing star itself can be removed and is made from a Magnesium alloy. The centre cap is plastic. The Magnesium star often corrodes but can be successfully restored.
Purists will tell you that the rear throwing star on the rear of the car above is fitted to the wrong side of the car. The angled edge of the star should face the direction of rotation, which the rear alloy does not.
The boot on the E31 is pretty capacious for a coupe. At the front of the boot, to the left is the Hi-Fi amplifier. There is a fixing at the top, the cover and amplifier can be lowered for access.
In the centre can be seen the ski-hatch, this should contain a 'sock' into which ski's can be pushed. Inside the car, the centre upper bolster of the rear seats is removed to allow the ski boot to unroll into the interior (don't try this - it is nigh-on impossible to get back in).
The E31 has two batteries connected in parallel that are fitted behind the carpeting to the left and right of the boot. Behind the left-hand carpet is also the jack and wheel-brace.
Fitted in the right-hand side carpet is the CD changer, this takes cartridges which accept 6 CD's. Being a 90's design the CD's can only contain audio tracks, MP3 CD's cannot be played.
The M70 is exceptionally powerful with masses of torque and this provides the major differences between the 840ci and 850ci. Whereas the 840ci is very quick, the 850ci is just as fast but much more refined, sounding more like a turbine than a piston engine. The only downside to the M70 is the fuel-consumption. There is no substitute to normally aspirated capacity and at 4988cc the 850ci has a lot of it! You also get the kudos of the V12, it really is a class act.
Although other world markets got the 5.4Ltr M73 engine, here in the UK we didn't, the only M73 850ci's that are seen for sale in the UK are imports.
The mechanical reliability of the M70 is excellent, they really are built like tanks, but in 2015 the early engines are getting on towards 25-years old. Even at this age the major mechanical items usually retain their integrity, pistons, rings, main bearings, big and small ends seem to last forever. But just like the M30, poor oil circulation at the top-end can lead to camshaft wear (due to loose banjo bolts). Some valve-guide wear can be seen on high-mileage engines.
The M70 engine employs an EML system (Electronic Motor Load) in addition to two ECU's (one for each cylinder bank). Instead of using throttle cables and mechanical throttle-bodies, the EML system uses motorised throttle-bodies (called DK motors). This concept removes the need for a separate traction-control system, idle-control valves or a cruise-control actuator. The throttle pedal is replaced by a potentiometer unit making the engine control entirely electronic. Components of this system can fail due to mechanical wear, in particular the DK motors (throttle bodies) can cause problems. However, in spite of the perceived complexity of the system, most problems are simply solved using DIY techniques.
This engine was also used in the E32 750i/L and there is a lot of experience available to help keep it healthy. Although the size and complexity of the engine is initially daunting, problems usually boil-down to simple causes which can be easily remedied using the vast experience of the E32 and E31 Forums. However, some apparently simple procedures such as changing all 12 spark plugs can try the patience due to the lack of access. Basic servicing costs are only slightly higher for the V12 primarily due to the extra cylinders and air-filters.
It will be noticed that the main wash bottle to the right does not have a filler cap, this is because this car is fitted with the high-pressure headlight wash system. With this option the main reservoir is located in the boot inside the spare wheel. The tank shown here is filled automatically under control of the General Module. The main reservoir in the boot is filled via a lid in the boot.
In front of the washer bottles is the engine air-filter housing.
At the right-front of the engine bay can be seen the oil-canister (far left of the picture), this contains the oil-filter element.
To the right of the picture is the ASC actuator. This system reduces engine power when traction is lost by shutting a secondary throttle-butterfly.
On models with cruise control, the actuator is located here and connected to the main throttle-body via a long Bowden cable.
Further back in the engine bay is the reservoir for the power steering fluid which also contains a filter. The same system is used for the brake booster and includes a pressure reservoir named a bomb due to its rotund shape, and the ability to explode if fiddled with.
Behind the power steering reservoir is the brake master cylinder. Surprisingly for a right-hand drive car, the master cylinder is on the opposite side to the brake pedal. This means that there are mechanical linkages across the interior of the firewall to operate the brake system. This can reduce the low-speed feel of the brake system.
Improvements to the feel can be made by lubrication of the linkages as described on this website.
Mechanically, both the M60 and M62 engines are impressively reliable. The M60 engine got an awful reputation in the '90's for cylinder wear due to the Nikasil process used to harden the aluminium bores. But in 2015 the Nikasil problems are long over, you are just as likely to see an M70 or M73 with worn bores. As long as basic servicing is performed on the engine (oil changes in particular) it will outlast the chassis.
Unfortunately, the cooling system is a weak spot (just as it was on the E32 and E38). The expansion bottle, radiator, auxiliary pump and hoses have a predilection to explode or leak. The viscous-coupled cooling fan often fails leading to overheating when stationary, or if you are unlucky, shedding the fan blades at 6500RPM, now, that makes an awful mess of the engine bay and bonnet! As long as the owner is aware that these items can cause problems and they are replaced before failure then the cooling system will operate correctly.
Apart from the cooling system, the V8's can suffer other small problems. The inlet manifold has a pressure control valve (PCV) fitted at the rear and this can fail. When it does, upsetting amounts of smoke appear at start-up and when under harsh acceleration, it also causes a bad idle, in fact, exactly the same problems that are present with bore-wear. Many owners are scared witless by this fault, but the repair is simple and the PCV costs around £40.
Over time various seals will fail around the inlet manifold leading to a bad idle. These are relatively easy to replace and the parts are cheap enough. The timing-chain tensioner will need replacing at around 100k and this will preserve the timing-chain guides. The guides are made from plastic and can fail if allowed to flop around due to a worn tensioner.
All in all, the M60 and M62 are excellent, reliable and economic engines that provide exciting performance.
Under the bonnet
The car shown above is an Orinoco Green example and is extremely rare, being 1 one of only four sold in the UK. It is this rarity that is more sought-after rather than the base Individual status. The E31 was produced in many colours, many more than was available in other models. Some of these colours are extremely rare, some (such as Byzanz Metallic, Atlantisblau, Bostongruan Metallic, Cordobarot Metallic and many others) were only seen on a single example each. Much more detailed information on the rarity of colour combinations can be found on the BMW 8 Series Registry which is the greatest source of E31 information available anywhere.
To summarise the Individual models, although an Individual model is more desirable, there are different levels of individuality! When it comes to the E31, there really are one-off examples available (but not often).
The Individual models are also defined by external colours that were not available as standard options, these standard colours are listed below:
The E38 7-Series Individual models formed a small percentage of the total sales, this increased the desirability of the few Individual examples that came onto the market. The same is not true for the E31, especially the 840ci.
Owning an E31
Owning an E31 is not very different to owning an E32 or E38 7-Series, well, apart from the cost of buying one in the first place. Whereas a '99 740i Sport will set you back around £3K, a '99 840ci Sport will set you back around £10k or more. But, once you have handed over your money, there really is not much difference in servicing and maintenance costs between the E31 and E32/E38. Both can be cripplingly expensive if a BMW main-dealer is used!
Fortunately, the E31 can be maintained using DIY methods just as easily as any other car, and is certainly less complicated than the E38. As the V12 and V8 engines were also used in the E32 and E38, there is a lot of experience of the engines and drive-train available on the Internet Forums (but not at the BMW main-dealers). As the E32 and E38 were mass-produced cars, spares are readily available both from BMW and in the second-hand market.
Both the V8 and V12 engines are extremely reliable mechanically, but both also suffer from niggly problems such as manifold leaks, PCV failure and coolant-system explosions. None of the problems are excessively expensive or complicated to repair yourself, but if you rely on a BMW main-dealer it is a costly business. More importantly, it is usually the diagnosis of a running problem that can be expensive if left to a main-dealer. There is very little experience of the V8 and V12 (especially the M70 V12) engines at BMW, they were rare in the '90's let alone in 2015. Unless you live up the road from Phoenix Motorsport or a similar expert you are going to find it hard to find anyone who knows what they are doing with these big engines.
Although the E31 is a heavy car, the suspension is man enough for the job but will see wear at some point. We've all seen the 'it costs £1000 to rebuild the front suspension' horror stories, well it might if you replaced the complete suspension using BMW parts. Fortunately, it doesn't disintegrate all at the same time and the individual parts are no more expensive than on other models.
The E31 suffers from the dreaded shimmy just the same as the E32 and E38, and this can be hard to trace and cure. My best advice is if you are buying an E31, don't buy one with shimmy. Still, sometimes shimmy can be sorted quickly and easily, it just in some cases that it causes endless problems.
These are heavy cars with large, normally-aspirated engines, so you can easily imagine that the fuel-consumption isn't going to be frugal. It certainly isn't if you utilise the full 286BPH/296BHP from the V8 and V12 engines, but that's only half the story. Both engines are designed to run at the optimum fuel/air mixture for economy when cruising, they have highly developed software to squeeze the most out of each drop of petrol.
As would be expected, the 4-valves per-cylinder, quad-cams and individual coil-over-plug units on the M60 and M62 V8 engines stretch the fuel further. The extra 400cc added to the M62 (compared to the M60) is offset by more advanced software (DME 3.3 for the M60 and DME 5.2 for the M62). Both the V8 variants have knock-sensors, these sense the detonation caused by ignition timing that is too advanced for the petrol octane being used. The ignition timing is retarded for low-octane fuel, and advanced when high-octane is used. This allows the extra energy present in higher-octane to be fully realised. It also allows the engine to be run on low-octane fuel without damage.
The consumption of the M62 840ci can be as high as 30 miles per Imperial gallon of 99 Octane fuel, but this can only be realised on a long motorway run. In the real world, for mixed journeys, the consumption is around 20MPG - 22MPG. If the same journeys are done in a more 'spirited' fashion the average can drop significantly.
CSi's - Alpina
The E31 is rare enough, but the 850CSi and Alpina
versions are even rarer and even faster......
....and a specialist subject that it beyond this short introduction!
Still, no time to contemplate that as the 300 Metre countdown flashes past at your exit. This is a tight one, so knock the shifter left into sport-mode, the revs rise to 2800 and then to around 4000 as you knock the stick backwards to select manual-mode and 3rd gear. The exit is a sweeping left-hander leading to a right-hander that tightens up considerably, but there is very little body-roll and the confident way the 840ci takes the corner precludes a need to use the brakes, in fact, as the exit turns back over the A3 you will find yourself hitting the throttle again to get the speed back up.
No need for 2nd gear though, there is endless torque at 3000 RPM. Squeezing on the power you can feel the back end just start to step out but there is no chance of losing it, the ASC reins in the over-steer but still the power is pushing you on faster. Over the bridge, brakes on hard, into 2nd gear and snap back onto the slip road heading back down the A3. Holding in 2nd gear you look over your shoulder at the A3, there is a Eurobox heading towards you, so throttle down, hold in 2nd until around 70MPH and then 3rd. As you enter the A3, the Eurobox looks like it is going backwards and you knock the shifter over to 'D' again to begin the short cruise towards home.
Once out of the junction and onto the A road, the car feels light and the steering accurate, the gears change a little earlier and 60MPH is quickly reached with just a little throttle. If the car has any problems with suspension wear, it is at this speed that it will show itself as a rapid shake through the steering wheel and a tendency to fall off the camber of the road. After a couple of minutes the climate control system allows heat from the vents which were previously automatically closed.
As a roundabout comes into view, Sports mode is selected on the Steptronic shifter, the car immediately drops down a gear and the speed drops off. Creeping onto the unsighted A3 slip-road, the traffic is clear and the throttle pedal is pushed towards the floor.
A lot of things happen in a split second, the 'box drops into 1st gear, the revs rise immediately and you are forcefully pushed into the sports seat. With a slight blink of the anti-skid control warning you are launched off the slip road as 6300RPM momentarily registers and 2nd gear is selected at lightening speed. You are already travelling at close to 50MPH. You just have time to check the wing mirror again as the revs reach the red-line and 3rd gear drops in. A glance at the speedo shows you are now travelling at an illegal 80MPH.
As the pedal is released the revs hang at 4400 until the software decides that you have finished thrashing the car and selects 4th gear, the revs drop to 2800 and then to 2200 as you pull the shifter back to 'D' and 5th gear engages.
The A/C controls are easy to set and adjust on the move, unlike the E38's digital controls which take a few pokes to get right, the controls are entirely analogue and quick to modify on the move.
Right, seatbelt on, door shut and start the engine. The custom rear boxes give a deep V8 burble that is barely heard in the cabin but is more vocal outside. Handbrake off, foot on the brake pedal and select Drive using the Steptronic shifter.
Driving the E31 840ci Sport
Although there is a manual control for fan speed, the system adjusts the setting to compensate for road-speed and also reduces the fan speed until the coolant temperature reaches a point that the unit is effective. Although this unit was superseded by a digital unit (in the E38), the analogue unit in the E31 is much easier (and quicker) to use and performs just as well as the later unit.
When set to fully automatic, the system controls ten stepper-motor controlled air flaps to keep the desired temperature constant and the windows fog-free.
The OBC functions include fuel consumption, estimated journey time and remaining fuel range. These displays can be initiated from the MID buttons or by pressing the end of the indicator.
The MID also displays warning messages of varying importance, from reminding that you have left the lights on to the more immediately important 'Engine oil pressure low'.
The MID also has some 'hidden' functions that can be used for simple diagnostics such as voltage and current measurements, instantaneous fuel consumption.
The glovebox is quite small but contains a rechargeable torch. Where the passenger airbag is not fitted there is an upper glovebox, most UK models have the airbag.
The centre console has three small compartments and an ashtray/lighter. The telephone (where fitted) consumes the area behind the ashtray and the compartment. The two rear storage compartments can be fitted with a cassette storage unit, or a CD storage unit. There are also pouches built into the front of the seats. And for storage - that's it!
When the door is fully closed, the top of the window tucks under the roof frame strip and pushes against the window seal. This system ensures an excellent aerodynamic finish and very low wind noise.
The black trim on the rear window also incorporates a seal that bridges the gap between the front and rear windows.
As the picture to the right shows, this system has no need for rain gutters, and although this reduces drag, the greatest benefit is the reduction of wind noise.
The front window is standard in operation, it includes 'single-touch open' from the window switches fitted to the driver's door. Unlike the software in the E38, the E31 achieves the same function through hardware, the window-switch has a double-switch action. A light press will drop the window only whilst the button is pressed. If the button is pressed harder, the second switch contact closes and the window will fully drop.
the rear window has to rotate as well as drop, the mechanism is unique to the E31.
The mirror adjustments are on the same panel. The CSi mirrors are much smaller than the standard mirrors but still give good visibility. The passenger mirror drops when the car is put in reverse as long as the driver/passenger adjustment selector is set to 'driver'.
The front windows automatically rise when 100MPH is reached!