BMW E34 buying guide: what to check, which engine

Is the BMW E34 a good car to buy?

Yes, if you buy on condition rather than mileage. A rust-free E34 with a known cooling and gearbox history is a good car; a cheap one with rust in the sills is a project.

For: Solid body and an interior that ages well; Wide engine choice, from the M40 four to the S38 of the M5; Simple to work on, with good parts supply.

Against: Sill rust from blocked sunroof drains; Brittle plastic cooling parts crack without warning; Water pump plastic impeller disintegrates.

What should I check when buying a used BMW E34?

Start with rust and old accident repairs, then the cooling system and the gearbox: those are the expensive ones. Take this list to a viewing.

Checked	Check	Why it matters	How bad
Body and rust
	Prise back the plastic sill covers on both sides and probe the full length of inner and outer sill, then press hard around each jacking pad.	Sill rust from blocked sunroof drains (sunroof cars)	Major
	Run a hand along the bottom edge of all four doors, inside and out, and open each door to check the drain slots are clear rather than packed with dirt.	Door bottoms rust from the inside out	Moderate
Gearbox and driveline
	Check the fluid warm where the box has a dipstick; the GM-built units have none and need a different level check.	Automatic gearbox ruined by neglected fluid (automatic cars)	Major
Cooling
	Inspect the tank and its seams for hairline cracks and dried coolant staining.	Brittle plastic cooling parts crack without warning	Major
	Look for weeping at the bottom of the pump, which indicates bearing and seal wear, then grip the pulley and feel for play or roughness.	Water pump plastic impeller disintegrates (M20 and M50 six-cylinder cars)	Major
Electrical
	With the ignition on, read every segment of the odometer and OBC display and cycle all the OBC functions, then check the service-interval lights.	Cluster pixels and ageing wiring	Minor

All 9 known issues of the E34

Which BMW E34 engine should I choose?

For most buyers a 525i with the 24-valve M50 is the sweet spot of power, parts supply and running costs. The table names the fault each engine family is known for.

Engine	Variants	Years	Known for
`M43`	518g, 518i	1994–1996	—
`M40`	518i	1989–1994	Snapped timing belt wrecks the engine
`M20`	520i, 525i	1988–1990	Snapped timing belt wrecks the engine
`M50`	520i, 525i, 525ix	1990–1996	Cooling-system plastics age and fail
`M21`	524td	1988–1991	Cracked head after overheating
`M51`	525td, 525tds	1991–1996	Turbocharger oil leaks and lost boost
`M30`	530i, 535i	1987–1992	Timing chain, tensioner and guide wear
`M60`	530i, 540i	1992–1996	Nikasil cylinder bore wear
`S38`	M5 3.6, M5 3.8	1988–1995	Head gasket and cooling weak points

Where do I find BMW E34 parts?

Search by part number or browse by category. Not listed? Post a request on the board.

21006 catalogue parts fit the E34 and 0 are for sale right now: browse them, look a part up in the parts catalogue or post a request.

How do I tell an early BMW E34 from a late one?

The big dividing lines are the switch from the M20 to the 24-valve M50 in the 520i and 525i, and the arrival of the M60 V8s in the 530i and 540i.

How do I read the BMW E34 chassis number?

The VIN has 17 characters; BMW parts catalogues use the last seven as the chassis number, so that is the number to quote when you order a part.