BMW M20B25 engine report, 325i E30
BMW M20B25 · 325i (E30)
2.5 LPetrolInline-61985–1991
74/100
Checked by hand
[good]
Cheap to buy, expensive to neglect
Only worth it if the price already reflects the risk.
ExcellentGoodSolidRiskyAvoid
- Known issues
- 5
- Critical
- 2
- Sources
- 18
Verdict
This one only makes sense priced low enough to leave room for repairs.
The timing belt and the head gasket are where the money is: either one letting go kills the engine, and the water pump normally gets done with the belt anyway. Oil leaks from seals and gaskets are very common, so expect weeping and get underneath to see how bad it actually is. On a manual, listen for judder pulling away, because the dual-mass flywheel and clutch wear out too and that is worth arguing about on price.
Specs
- Displacement
- 2.5 L
- Layout
- Inline-6
- Fuel
- Petrol
- Production
- 1977 – 1993
- Chassis
- E30
- Fitted
- 1985–1991
Known issues
5 confirmed · sorted by severity
CriticalTiming belt failure
Rubber timing belt (including wet/in-oil-bath belts) degrades or snaps, often due to missed replacement intervals.
Symptoms
- Warning Light
How often
Occasional · Expected maintenance. Does not normally destroy the engine. Not safely drivable.
CriticalHead gasket failure
Head gasket failure, often preceded by overheating; can lead to a warped head or cracked block if not addressed.
Symptoms
- Coolant Loss
- Smoke (White/Blue/Black)
- Warning Light
How often
Occasional · Age-related wear. Does not normally destroy the engine. Not safely drivable.
ModerateWater pump failure
Water pump seal or bearing failure (mechanical or electric pump), causing coolant loss.
Symptoms
- Coolant Loss
- Warning Light
How often
Common · Age-related wear. Does not normally destroy the engine. Still drivable.
ModerateDual-mass flywheel / clutch wear
Dual-mass flywheel wear causing rattle/vibration, often coinciding with clutch replacement interval.
Symptoms
- Excessive Vibration
- Knocking Noise
How often
Occasional · Expected maintenance. Can destroy the engine if ignored. Still drivable.
LowOil leak from seals or gaskets
Valve cover gasket, rear main seal, or front main seal degradation causing external oil leaks.
Symptoms
- Oil Consumption
How often
Very common · Age-related wear. Does not normally destroy the engine. Still drivable.
Check the car you're looking at
Owners rarely say at what mileage this engine's problems start, so they aren't sorted by mileage here. These are the ones to ask the seller about, the ones it's best known for first.
What to ask about
Buying checklist
BMW M20B25 (325i E30) · Buying checklist
Sources
Updated 15 Sept 2026 · scoring v2.7
Behind this report sit 18 owner posts, forum threads and official records. Nothing gets on the list on one person's word. It takes a recall, or owners on separate platforms describing the same fault. The score then sets how often a problem turns up against the damage it does.