Valve cover and PCV failure
Attaches to N55 at engine level · Engine · carried by 5 variants across 5 chassis
Overview
Valve cover and PCV failure is a common fault recorded against N55 at engine level, typically from 100–180k km. It shows up as oil weeping down the back of the block, whistling from the engine at idle, rough idle, high crankcase vacuum pulling oil seals. Where it's documented, the repair runs €400–€700 (cover and gasket at an independent, costs dated 2026-07), and it can be checked before you buy. 5 variants across 5 chassis in this database inherit it.
What happens
Symptom. Oil weeping down the back of the block, whistling from the engine at idle, rough idle, high crankcase vacuum pulling oil seals.
Cause. The crankcase ventilation diaphragm is integrated into the plastic valve cover, so the whole cover is the repair.
How to check it
Static checks
Listen for a whistle at idle with the oil cap on, then remove the cap, a strong change in idle points to the PCV. Look for oil residue at the rear of the head.
Engine off, ideally on a lift.
Every variant that carries this
| Variant | Chassis | Body | Years | Risk | Good buy | Cost as % of good buy |
|---|---|---|---|---|---|---|
| 335i N55 | E90 | sedan | 2010–2011 | R3 | €11,700 | 5% |
| 335i N55 | E92 | coupe | 2010–2013 | R3 | €13,450 | 4% |
| 335i N55 | E93 | convertible | 2010–2013 | R3 | €13,100 | 4% |
| 135i N55 | E82 | coupe | 2010–2013 | R3 | €12,600 | 4% |
| 135i N55 | E88 | convertible | 2010–2013 | R3 | €13,300 | 4% |
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.