BMW's flagship grand tourer of the 1990s, built from 1989 to 1999 with a pillarless coupe body and one of the first production electronic throttle systems. The V12-powered 850i was renamed 850Ci from 1992, with the 5.4-litre M73 replacing the 5.0-litre M70 from late 1994. The M73 was offered only with the ZF 5HP30 five-speed automatic, while M70 cars were available with either a six-speed Getrag manual or the ZF 4HP24 four-speed automatic, all driving the rear wheels.· more· less
V12 engines are mechanically robustStrong specialist support network
Aging electronics are costly to fixSome body parts are discontinued
Buy if: You want a mechanically sound V12 grand tourer and can budget for specialist maintenance of 30-year-old electronics and seals.
Avoid if: You need affordable parts availability or cannot source a specialist familiar with the E31 platform.
Electronic throttle body encoder plates and potentiometers wear out with age, causing EML warning lights and single-bank running · more· less
Both the M70 and M73 use fly-by-wire electronic throttle bodies (EML system) with one per cylinder bank. The encoder plates that communicate throttle position wear down after 25+ years, and the molded resistors can fail. Symptoms include EML warning light, loss of power, running on only one bank (six cylinders), delayed throttle response, or intermittent surging. BMW no longer supplies new throttle bodies (the original price was around €4,000 per unit). Specialist rebuild services replace the encoder plates and recalibrate both units for approximately €500-800 for the pair. If the internal actuator motors are also degraded, total cost including labor can reach €1,000-1,500. The M73 uses stepper motors; the M70's earlier EML system uses DC motors. The EML system has built-in diagnostics accessible through the accelerator pedal, which a knowledgeable specialist can use before committing to a rebuild.
Oil sump gasket leak
up to €3,5002 of 8
The gasket on the two-layer alloy sump leaks where it meets the block, and proper repair requires gearbox removal · more· less
The M70 and M73 both use a two-layer aluminium sump assembly. The gasket between the sump and the engine block degrades over time and commonly leaks. The difficulty is that the rear sump bolts are only accessible with the gearbox removed, making this a major labor job at a specialist. Some workshops drill access holes through the bellhousing as a workaround, but this is considered a compromise. Budget €1,500-2,500 at a specialist, or €2,500-3,500 if combined with other seals during the gearbox-out procedure. Many owners choose to address multiple oil leaks (valve covers, timing cover, rear main seal) at the same time to justify the labor cost.
Cooling system component failure
up to €2,5003 of 8
Water pump bearing failure, heater hose rupture, and radiator end-tank cracking are all common age-related failures · more· less
The cooling system is the most critical maintenance area on any E31 V12. The water pump can suffer sudden bearing failure; on M73 cars the larger crank pulley damper must come off first, adding labor. The radiator has plastic end tanks that become brittle and crack at the hose connections. The heater hoses route close to engine movement points and can rupture unexpectedly, sometimes described as the infamous E31 exploding coolant hose. The viscous fan clutch can also fail, reducing airflow. A preventive overhaul of the entire cooling system (water pump, thermostat, all hoses, radiator if original) costs €1,200-2,000 at a specialist. An emergency repair after a failure, potentially including towing and consequential overheating damage, can reach €2,500.
Banjo bolt cam spray bar oil starvation (M70, 1989-1994)
up to €5,0004 of 8
Hollow banjo bolts in the M70 work loose and starve the front cam lobes of oil, potentially leading to rocker seizure · more· less
This issue affects only M70-engined cars (1989-1994). The M70 uses finger-type rocker arms lubricated by a spray bar fed through hollow banjo bolts from the upper oil gallery. These bolts cannot be over-tightened due to their hollow construction, and thread-lock breaks down over time. When they loosen, oil flow to the front cam lobes drops, causing the distinctive tappet rattle that worsens over time. If ignored, the rockers can seize and snap, requiring cylinder head removal and camshaft replacement. The M73 (1994-1999) uses roller followers and is not affected. If caught early, re-torquing with fresh thread-lock and an oil change costs under €300. If cam lobe or rocker damage has occurred, expect €1,500-5,000 for camshaft replacement and head work.
Valve stem seal degradation
up to €4,0005 of 8
Hardened valve stem seals cause increasing oil consumption and blue smoke on startup or overrun · more· less
After 25+ years, the valve stem seals on both the M70 and M73 harden and no longer prevent oil from seeping past the valve stems into the combustion chambers. Symptoms include blue smoke on startup (especially after overnight sitting), smoke on trailing throttle overrun, and gradually increasing oil consumption. The V12 has 24 valves, so a full seal replacement is labor-intensive. Parts cost approximately €150-200 for a complete set. The seals can be replaced with the heads in situ using a compressed-air valve spring tool, avoiding head removal. Specialist labor for this procedure is typically €1,800-3,500. If cylinder head removal is also needed, total cost rises to €3,000-4,000.
ABS charge pump failure
up to €1,2006 of 8
The electric charge pump on the ABS hydraulic block seizes from age and lack of use, switching off ABS and traction control while ordinary braking keeps working · more· less
On M70 cars the ABS unit and its pump are separate from the traction control: early automatics had engine-only ASC as standard and ASC+T as an option, manual cars had ASC+T as standard, and ASC+T became standard on UK automatics from around March 1992. Where an M70 car has ASC+T, it uses its own hydraulic unit with a pressure accumulator, and a fault confined to that unit switches off traction control while ABS keeps working. M73 cars combine ABS and ASC+T in one Bosch hydraulic block, and later cars can have DSC, which incorporates it. The charge pump is the electric pump on the ABS hydraulic block: it returns brake fluid during ABS regulation and, where ABS and ASC+T share one Bosch block, also builds the pressure for traction-control braking. It can seize from age and lack of use, which lights the ABS and ASC warning lamps and switches off ABS and traction control; ordinary braking keeps working as on a car without ABS. Activating the pump through diagnostic software sometimes frees it, although the fault can return. A seized motor can usually be overhauled or swapped without replacing the hydraulic block; only pump or valve damage calls for a rebuilt or replacement block. Specialists quote motor-only overhauls individually. For comparison, a genuine BMW replacement for the later combined ABS/ASC+T block is listed at about €1,700 before fitting, and a specialist rebuild of the earlier separate ASC+T unit costs about €790 before fitting. Exercising the pump by triggering ABS activation in a safe environment periodically helps prevent seizure.
Door handle pivot failure
up to €5007 of 8
The original pot-metal door handle pivots wear and fracture, making the door unopenable from outside · more· less
The E31's exterior door handles use an internal zinc die-cast (pot-metal) pivot bar that wears and fractures with age and use. Over time this pivot develops play and eventually breaks, leaving the door unable to be opened from the outside. BMW has discontinued the original part. Aftermarket repair kits with a steel pivot bar cost about €100 per side from E31 specialists (Wokke lists €98), and some specialists rebuild removed handles as a send-in service. The kit price does not include fitting, because the interior door panel must come off to remove the handle assembly. Given the age of all E31s, most will need this repair at some point if it has not already been done. Check both handles for excessive play during any pre-purchase inspection.
Wiring harness and connector degradation
up to €3,0008 of 8
Wiring insulation becomes brittle and connectors corrode after 25+ years, causing intermittent electrical faults · more· less
At 25-35 years old, the E31's wiring insulation becomes brittle from heat cycling, especially in the engine bay. Connectors develop corrosion and increase resistance, causing intermittent faults that are difficult to diagnose. Common symptoms include the GM2 general module malfunctioning (affecting windows, locks, and interior lights), intermittent engine management faults, and boot lid wiring failures (the looms that flex through the boot lid hinges break, usually starting with the brown ground wires, which triggers bulb warnings, typically when reversing). The blower final stage resistor (known as the Sword) can also fail due to overheated FET transistors, causing the cabin fan to run at full speed or not at all. Individual harness section repairs cost €200-500, but a car with multiple degraded sections can accumulate €1,500-3,000 in electrical work. Proactive inspection and repair of engine bay wiring is strongly recommended.
Mechanically robust V12, but age-related electronics and seals need specialist attention
Both the M70 and M73 V12 engines are fundamentally strong, with no widespread reports of catastrophic internal engine failure. Head gasket failures and crankshaft bearing issues are virtually unheard of. The timing chain is durable and does not require scheduled replacement. The main ownership challenges are electronic degradation (EML throttle system, wiring harnesses, ABS pump), age-related seal failures (sump gasket, valve stems), and cooling system components that are now 25-35 years old. M70 cars (1989-1994) need the banjo bolt cam lubrication checked as a priority. M73 cars (1994-1999) are generally considered more refined and slightly more reliable due to roller followers and the ZF 5HP30 five-speed automatic that replaced the M70's four-speed 4HP24. A knowledgeable E31 specialist is essential for cost-effective ownership.
Service history
Complete specialist or dealer records are essential. Verify oil changes, coolant system service, and any major repairs. Gaps in history on a 30-year-old V12 are a serious concern.
Cold start
Start the engine completely cold. Both banks should fire immediately. Listen for any tappet noise in the first 30 seconds and watch for blue smoke from the exhaust.
Test drive
Drive for at least 30 minutes including motorway speeds. Monitor the temperature gauge closely and watch for EML warning lights. On automatic cars, the gearbox should shift smoothly through all gears.
Underside inspection
Put the car on a lift and inspect the entire underside for oil leaks, coolant traces, rust, and damaged components. Pay special attention to the sump area and all cooling hoses.
Inspect rear window for delamination
Look at the rear window from inside the car for milky or cloudy patches. The E31 has a laminated rear window, and delamination between the glass layers is a documented age-related fault; a genuine BMW replacement screen costs about €850 before fitting.
Specific for this vehicle
Listen for M70 tappet rattle on cold start (1989-1994 cars)
A clacking noise from the cylinder heads on M70 cars indicates banjo bolt loosening and cam spray bar oil starvation. This must be addressed before further driving.
Check EML light and throttle response
Drive the car and watch for the EML warning light. Test full throttle in a safe situation. Both banks should pull equally. Hesitation or surging suggests throttle body encoder wear.
Inspect cooling system thoroughly
Check all hoses for swelling or hardness, inspect radiator end tanks for cracks, and check the water pump for bearing play. Any original cooling components are overdue for replacement.
+ 4 more checksShow less
Test both exterior door handles
Open and close both doors from outside. Any excessive play, looseness, or grinding feel in the handle indicates the pot-metal pivot is worn and needs replacing.
Check for oil leaks from underneath
Inspect the sump gasket area, valve covers, and timing cover for oil seepage. The sump gasket is the most costly to repair due to gearbox removal. Any fresh oil drips warrant a specialist assessment.
Verify ABS and ASC function
Check for ABS and ASC warning lights on the dashboard. The charge pump can seize from lack of use. If the lights stay on, the charge pump or a wheel speed sensor has likely failed; have the fault codes read before budgeting for a pump overhaul.
Check the MID display for pixel loss
Inspect the centre-console on-board computer display (MID), which also shows the check control messages, for missing or fading pixel columns. The cause is a deteriorating flat ribbon cable between the LCD and its circuit board, a common fault that can affect every E31. Specialist repair is available and should be factored into negotiation.
Recalls and Technical Service Bulletins
Radiator cap replacement: BMW campaign 00170601, the non-US version of BMW's 1998 radiator-cap action for E31, E32, E34 and E36 models. No build window is published for the E31; applicability is VIN-specificVerify with VIN
One BMW campaign is traceable for the E31: campaign 00170601, the non-US version of the 1998 radiator-cap replacement. BMW publishes no E31 build window for it, so whether a car was included depends on its VIN. European recall archives have limited coverage for cars of this era, so ask a BMW dealer to check the VIN for open campaigns and for confirmation that this campaign was completed.
Warranty Status
New-car warranty (Germany: 1 year)Expired on every E31
Anti-corrosion warranty (UK: 6 years)Expired on every E31
Warranty terms depended on the market. In Germany, BMW's new-car warranty for cars of this era ran for one year from delivery; in the UK, the anti-corrosion warranty was six years. All original cover has expired on every E31, and BMW offers no extended manufacturer warranty for it. Third-party classic car warranties exist but typically exclude pre-existing conditions, and some specialists warrant their own completed work. Parts supply is mixed: mechanical engine components, gaskets and common service items remain available through BMW and aftermarket suppliers, but some body and interior parts, notably the original door handle pivots and some trim pieces, are discontinued.
Sources: Research draws on model-specific owner forums and owner communities, recall information from official authorities, German automotive press, and multiple workshop cost references cross-checked against each other.
This report is for informational purposes only and does not constitute professional advice. Estimates may be inaccurate. Always have a qualified specialist inspect the vehicle before purchase. We accept no liability for decisions made based on this information.
