BMW M20B25 engine report
BMW M20B25 · 325i (E30)
2.5 LPetrolInline-61985–1991
82/100
[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.
Evidence
1 owner report backs this, confidence 50/100.
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.
Evidence
1 owner report backs this, confidence 40/100.
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.
Evidence
2 owner reports back this, confidence 55/100.
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.
Evidence
3 owner reports back this, confidence 40/100.
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.
Evidence
5 owner reports back this, confidence 55/100.
- Critical
- High
- Moderate
- Low
Timing belt failurefrom 79k km
Head gasket failurefrom 179k km
Water pump failurefrom 79k km
Dual-mass flywheel / clutch wearfrom 306k km
Oil leak from seals or gasketsfrom 246k km
Buying checklist
0 of 5 checked
Sources
Updated 15 Sept 2026 · scoring v2.7
This report combines 18 owner posts, forum threads and official records. An issue only makes the list once the evidence is strong enough, an official recall on its own or several independent owner reports, and the score weighs how often each problem happens against how bad it is when it does.