Coolant expansion tank cracking
Attaches to E9X at chassis level · Cooling · carried by 65 variants across 4 chassis
Overview
Coolant expansion tank cracking is a common fault recorded against E9X at chassis level, typically from 90–200k km. It shows up as coolant smell after a drive, slow unexplained loss of coolant, crusty residue around the tank seams. Where it's documented, the repair runs €120–€250 (tank and cap at an independent, costs dated 2026-07), and it can be checked before you buy. 65 variants across 4 chassis in this database inherit it.
What happens
Symptom. Coolant smell after a drive, slow unexplained loss of coolant, crusty residue around the tank seams.
Cause. The plastic tank goes brittle with age and splits, usually at a seam or around the level sensor.
How to check it
Static checks
Look at the tank with the engine warm, dried coolant leaves a white or pink crust. Cheap to fix, but it tells you how the car has been maintained.
Engine off, ideally on a lift.
Every variant that carries this
| Variant | Chassis | Body | Years | Risk | Good buy | Cost as % of good buy |
|---|---|---|---|---|---|---|
| 318i N46 | E90 | sedan | 2005–2011 | R3 | €3,100 | 6% |
| 318i N46 | E91 | wagon | 2005–2011 | R3 | €3,300 | 6% |
| 320i N46 | E90 | sedan | 2005–2007 | R3 | €3,400 | 5% |
| 320i N46 | E91 | wagon | 2005–2007 | R3 | €3,600 | 5% |
| 320i N43 | E90 | sedan | 2007–2011 | R4 | €3,950 | 5% |
| 320i N43 | E91 | wagon | 2007–2011 | R4 | €4,200 | 4% |
| 320i N43 | E92 | coupe | 2007–2011 | R4 | €4,550 | 4% |
| 320i N43 | E93 | convertible | 2007–2011 | R4 | €4,450 | 4% |
| 323i N52 | E90 | sedan | 2005–2007 | R2 | €4,050 | 5% |
| 323i N52 | E91 | wagon | 2005–2007 | R2 | €4,300 | 4% |
| 323i N52 | E92 | coupe | 2006–2007 | R2 | €4,650 | 4% |
| 325i N52 | E90 | sedan | 2005–2007 | R2 | €4,750 | 4% |
| 325i N52 | E91 | wagon | 2005–2007 | R2 | €5,050 | 4% |
| 325i N52 | E92 | coupe | 2006–2007 | R2 | €5,450 | 3% |
| 325i N52 | E93 | convertible | 2007 | R2 | €5,350 | 3% |
| 325i N53 | E90 | sedan | 2007–2011 | R4 | €5,250 | 4% |
| 325i N53 | E91 | wagon | 2007–2012 | R4 | €5,550 | 3% |
| 325i N53 | E92 | coupe | 2007–2013 | R4 | €6,050 | 3% |
| 325i N53 | E93 | convertible | 2007–2013 | R4 | €5,900 | 3% |
| 328i N52 | E90 | sedan | 2006–2011 | R2 | €5,150 | 4% |
| 328i N52 | E91 | wagon | 2006–2012 | R2 | €5,450 | 3% |
| 328i N52 | E92 | coupe | 2006–2013 | R2 | €5,950 | 3% |
| 328i N52 | E93 | convertible | 2007–2013 | R2 | €5,750 | 3% |
| 330i N52 | E90 | sedan | 2005–2007 | R2 | €5,600 | 3% |
| 330i N52 | E91 | wagon | 2005–2007 | R2 | €5,950 | 3% |
| 330i N52 | E92 | coupe | 2006–2007 | R2 | €6,450 | 3% |
| 330i N53 | E90 | sedan | 2007–2011 | R4 | €6,000 | 3% |
| 330i N53 | E91 | wagon | 2007–2011 | R4 | €6,350 | 3% |
| 330i N53 | E92 | coupe | 2007–2011 | R4 | €6,900 | 3% |
| 330i N53 | E93 | convertible | 2007–2011 | R4 | €6,750 | 3% |
| 335i N54 | E90 | sedan | 2006–2010 | R4 | €7,350 | 3% |
| 335i N54 | E92 | coupe | 2006–2010 | R4 | €8,450 | 2% |
| 335i N54 | E93 | convertible | 2007–2010 | R4 | €8,250 | 2% |
| 335i N55 | E90 | sedan | 2010–2011 | R3 | €11,700 | 2% |
| 335i N55 | E92 | coupe | 2010–2013 | R3 | €13,450 | 1% |
| 335i N55 | E93 | convertible | 2010–2013 | R3 | €13,100 | 1% |
| 316d N47 | E90 | sedan | 2009–2011 | R5 | €4,200 | 4% |
| 316d N47 | E91 | wagon | 2009–2011 | R5 | €4,450 | 4% |
| 318d N47 | E90 | sedan | 2007–2011 | R5 | €4,100 | 5% |
| 318d N47 | E91 | wagon | 2007–2011 | R5 | €4,350 | 4% |
| 320d M47 | E90 | sedan | 2005–2007 | R3 | €3,800 | 5% |
| 320d M47 | E91 | wagon | 2005–2007 | R3 | €4,050 | 5% |
| 320d N47 | E90 | sedan | 2007–2011 | R5 | €4,400 | 4% |
| 320d N47 | E91 | wagon | 2007–2012 | R5 | €4,650 | 4% |
| 320d N47 | E92 | coupe | 2007–2013 | R5 | €5,050 | 4% |
| 320d N47 | E93 | convertible | 2007–2013 | R5 | €4,950 | 4% |
| 325d M57 | E90 | sedan | 2006–2010 | R2 | €5,200 | 4% |
| 325d M57 | E91 | wagon | 2006–2010 | R2 | €5,500 | 3% |
| 325d M57 | E92 | coupe | 2006–2010 | R2 | €6,000 | 3% |
| 325d N57 | E90 | sedan | 2010–2011 | R3 | €7,200 | 3% |
| 325d N57 | E91 | wagon | 2010–2012 | R3 | €7,650 | 2% |
| 325d N57 | E92 | coupe | 2010–2013 | R3 | €8,300 | 2% |
| 330d M57 | E90 | sedan | 2005–2008 | R2 | €5,950 | 3% |
| 330d M57 | E91 | wagon | 2005–2008 | R2 | €6,300 | 3% |
| 330d M57 | E92 | coupe | 2006–2008 | R2 | €6,850 | 3% |
| 330d M57 | E93 | convertible | 2007–2008 | R2 | €6,700 | 3% |
| 330d N57 | E90 | sedan | 2008–2011 | R3 | €8,500 | 2% |
| 330d N57 | E91 | wagon | 2008–2012 | R3 | €9,050 | 2% |
| 330d N57 | E92 | coupe | 2008–2013 | R3 | €9,000 | 2% |
| 330d N57 | E93 | convertible | 2008–2013 | R3 | €8,750 | 2% |
| 335d M57 | E90 | sedan | 2006–2010 | R3 | €6,900 | 3% |
| 335d M57 | E92 | coupe | 2006–2010 | R3 | €7,950 | 2% |
| M3 S65 | E90 | sedan | 2007–2011 | R4 | €35,700 | 1% |
| M3 S65 | E92 | coupe | 2007–2013 | R4 | €35,000 | 1% |
| M3 S65 | E93 | convertible | 2007–2013 | R4 | €30,800 | 1% |
The last column is the point. The same repair is an inconvenience on one variant and a reason to scrap the car on another. A failure costing a quarter of the vehicle's value changes the purchase decision regardless of how rare it is.