BMW 730d Coolant Expansion Tank Crack
BMW
7 Series
2002
M57N/M57N2 3.0d
⚡ Quick Summary
Severity Level
Medium
Safe to Drive?
🚫 Do NOT Drive
Safety Impact
Direct safety risk — affects safe operation of the vehicle
Urgency Level
🟡 Monitor Closely
The plastic coolant expansion tank on E65/E66 is a known failure item. The plastic becomes brittle with heat cycling and develops cracks, leading to coolant loss and eventual overheating. The tank should be replaced preventively at 80,000 miles or any age over 8 years regardless of apparent condition.
Repair / Solution
No confirmed fixes yet. Share yours below.
⚠️ Wrong Diagnosis?
No commonly reported misdiagnoses for this fault yet. If you have replaced a part that did not fix this BMW 7 Series 2002 problem, submit a wrong diagnosis report — it helps other drivers avoid the same costly mistake.
🚗 More About This Vehicle
Explore more BMW models
Help other owners by sharing your experience.
Your real-world fix helps thousands of drivers worldwide. Takes 2 minutes.