M51
BMW · M51 2.5 Diesel I6
1991–2000
"Pre-common-rail indirect injection diesel. Cast iron tractor engine. Injection pump main failure at 250k+ km. No swirl flaps. No DPF."
Mileage Risk Timeline
When problems typically appear — enter your mileage to see your risk zone
Known Issues 2
Injection pump hot start failure
▸Won't restart when hot
Bosch pump electronics degrade. Relay timer mod as temp fix.
Αντλία — ζεστή εκκίνηση πρόβλημα. €500-1,200.
Cylinder head cracking
▸Coolant loss, white smoke
Aluminium head cracks if cooling neglected.
Ρωγμή κεφαλής 200k+. Ελέγξτε στην αγορά.
Models with M51 3
Other BMW Engines
Tuning Potential
Chip to ~175hp
Frequently Asked Questions
Is the BMW M51 reliable?
The BMW M51 scores 68/100 with a verdict of ACCEPTABLE. It has 2 documented issues with total repair costs between €1,500 and €3,700.
What are the common problems with the M51?
The most common issues are:
- Injection pump hot start failure — high, repair cost €500–€1,200, 200,000 km–350,000 km
- Cylinder head cracking — high, repair cost €1,000–€2,500, 200,000 km–350,000 km
What cars use the BMW M51?
How much does it cost to repair the M51?
Total potential repair costs for all 2 known issues range from €1,500 to €3,700. The most expensive issue is typically .
What years was the M51 produced?
The BMW M51 was produced from 1991 to 2000. It is a 2497cc I6 diesel engine.
Verdict and scores are editorial opinions based on aggregated data. Learn about our methodology. Not a substitute for professional inspection.