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BMW M21 engine: specs and known issues

The BMW M21 is a turbocharged inline-six diesel engine with a 2.4-liter displacement, produced 1983–1991, per Wikipedia. We do not have repair prices for it yet.

Specs and history from Wikipedia (revisions listed below)

M21 at a glance

Production	1983–1991	[1]
Configuration	Straight-6	[1]
Displacement	2443 cc (149.1 cu in)	[1]
Fuel type	Diesel fuel 45 CN (DIN 51601)	[1]
Forced induction	Garrett T03 ('td' versions), None ('d' versions)	[1]
Valvetrain	SOHC 2 valves x cyl.	[1]
Block	Cast iron	[1]
Bore × stroke	80 mm (3.15 in) × 81 mm (3.19 in)	[1]

Cars with the M21

Cars and chassis codes named in Wikipedia's article on this engine. It can include related or successor models, so treat it as a lead and check your exact car. Open a linked model to see its repair costs.

Model pages for the M21

Chassis pages whose cars, per Wikipedia, used this engine.

E30 3 Series E28 5 Series E34 5 Series

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Before and after

Predecessor: None
Successor: M51

Related engines

BMW M106 (1982–1986)
BMW M50 (1990–1995)
BMW M102 (1980–1982)
BMW S14 (1986–1991)
BMW M40 (1987–1994)

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Common questions

When was the BMW M21 engine produced?

1983–1991, per Wikipedia.

Sources

Wikipedia: BMW M21 (revision 1372467812, read 2026-10-23)