(BUYING GUIDE) Reliability of the used BMW 7 Series E38

BMW 7 Series E38 (1994–2001) Reliability: A Complete Guide and Pre-Buy Advice

The BMW 7 Series E38 is the embodiment of understated luxury and German precision.
But before buying one, it is crucial to know its mechanical and electronic weaknesses .
Here is a comprehensive guide to identifying known problems and learning how to spot them during a test .

Petrol engines: powerful but demanding

M52 / M52TU 6-cylinder in-line: 728i

Known problems:

Oil leaks (rocker cover, crankcase)
Water pump and expansion tank are fragile.
Faulty camshaft/crankshaft position sensors
Worn VANOS seals

To be checked during the test:

Smell of hot oil → probable leak
Unstable temperature gauge → cooling system at risk
Jerking at low engine speeds → faulty sensor or VANOS
Metallic noise when cold → worn chain tensioner

💡 A well-maintained 728i remains one of the most reliable engines.

M62 / M62TU V8: 735i and 740i

Known problems:

Multiple oil leaks (crankcase, valve covers, breather)
Fragile supply chain guides
VANOS and PCV faulty (TU versions)
Sensitive cooling system

To be checked :

Clunking noise when cold → worn chain guides
Blue smoke → valve stem seals
Unstable idle → breather problem
Abnormal engine temperature → water pump or thermostat

💬 Noble engine, reliable after timing belt overhaul.

M73 V12: 750i / 750iL

Known problems:

Oil and coolant leaks
Fragile engine control units (DMEs)
Water pump and radiator with a limited lifespan
Very expensive maintenance

To be checked :

Slow or hesitant start → faulty sensors
Coolant smell → leak at the front of the engine
Engine warning lights illuminated → dual-computer electronic management

💡 The V12 remains a mechanical marvel, but requires a substantial maintenance budget.

Diesel engines: robust but sensitive to age

M51: 725tds

Known problems:

Fragile Bosch VP37 injection pump
Aging turbo
Cylinder head gasket after overheating
Frequent oil leaks

To be checked :

Difficult cold start → worn pump
Black smoke when accelerating → injectors or turbo
Rapid overheating → possible blown head gasket

💬 Reliable if properly monitored, but often overlooked in the market.

M57: 730d

Known problems:

Fragile intake swirl flaps
Sensitive mass airflow sensor and EGR
Turbo to watch
Aging injectors

To be checked :

Blue smoke → turbocharger nearing the end of its life
Loss of power → swirl flaps or mass airflow sensor
Vibrations at idle → injector or engine mount

💡 Very good engine, solid once made reliable.

Automatic transmission

Known problems:

Jerky shifting during gear changes
Worn torque converter
Worn hydraulic block
Oil leaks from the crankcase

To be checked :

Smooth, shock-free transition from D to R
No wheelspin during acceleration
Gearbox oil level correct (clean red oil)
Recent oil change documented

💡 Oil change every 60–80,000 km = guarantee of longevity.

Suspension and steering

Known problems:

Worn silent blocks and suspension arms
fragile front ball joints
Leaky rack
Faulty rear air suspension (IL versions)

To be checked :

Clunking noises at low speed → tired arms
Stiff or noisy steering → hydraulic leak
Rear end sagging after one night → tire leak

💬 A healthy E38 offers royal comfort and precise steering.

Electronics and electricity

Known problems:

Dead pixels on screen or counter
Faulty ABS/DSC module
Power windows or electric seats stuck
Fussy ventilation (final resistance)

To be checked :

All pixels must be displayed upon contact
No engine or ABS warning lights illuminated
Air conditioning, windows and sunroof must all work perfectly
Stable wind speed (no random, erratic speed fluctuations)

💡 BMW electronics from the 90s are aging, but still repairable.

Cooling

Known problems:

Cracked expansion tank
fragile water pump
Aging radiator or thermostat

To be checked :

Visible cracks in the plastic of the vase
Abnormal pressure in the hot circuit
Temperature gauge perfectly centered while driving

💡 Overheating = immediate danger to the cylinder head gaskets and cylinder head.

Bodywork and corrosion

Known problems:

Rear wings susceptible to rust
Corroded rocker panels and jack supports
Trunk or fuel filler flap edge

To be checked :

Run your hand behind the wings → roughness = corrosion
Inspect the sills and wheel arches
Check the trunk floor under the carpet.

💬 An E38 stored indoors remains generally well protected.

Interior and comfort

Known problems:

Cracked driver's leather
Sunroof that's stuck
Sticky or broken buttons
Weakening air conditioning

To be checked :

Electric seats → all settings must work
Smooth and quiet sunroof
Air conditioning: constant cold air
Check for moisture under the floor mats

💡 The interior of a well-preserved E38 remains a model of perceived quality.

Reliability verdict and quick check before purchase

Category	Reliability	Key test being tested
728i	⭐⭐⭐⭐☆	Leaks, stable temperature
735i / 740i	⭐⭐⭐☆☆	Cold start clunk
750i	⭐⭐☆☆☆	Functional electronics
730d	⭐⭐⭐⭐☆	Turbo, smooth power
Automatic transmission	⭐⭐⭐☆☆	Gentle passages
Suspension	⭐⭐⭐☆☆	No clicking
Electronic	⭐⭐☆☆☆	No lights or dead pixels
Body	⭐⭐⭐⭐☆	Healthy rocker panels