Skip to content
KickTyres
MajorCommonFluid Leaks

BMW 3 Series: Valve cover gasket leak and cracked plastic valve cover (3.0 N55 turbo petrol, 335i)

Valve cover gasket leak and cracked plastic valve cover (3.0 N55 turbo petrol, 335i) is a common fluid leaks fault on the BMW 3 Series on the 2010–2015 cars, and we rate it major. Putting it right costs ≈A$830 to ≈A$2,020 at independent workshop rates, shown as an approximate guide in Australian dollars. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 92 documented faults on the BMW 3 Series.

Vehicle
BMW 3 Series
Engine
N55
Years
2010–2015
Fuel
petrol
System
Fluid Leaks

This page covers the BMW 3 Series as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All BMW 3 Series faults92 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Rocker / valve cover or Turbocharger yet. We would rather show none than show a picture of a different part.

What goes wrong

A leaking valve cover gasket, or a cracked plastic valve cover with its built-in PCV valve, is a known issue on the 3.0 N55 turbo petrol six in the 335i. Heat cycling hardens the gasket and can crack the plastic cover, so oil seeps out and can drip onto the hot exhaust side. Look for a burning oil smell, smoke from the engine bay and, in worse cases, oil in the spark plug wells that causes misfires. The usual fix is a new valve cover with its gasket, which is a long labour job.

What you would notice

  • Burning oil smell after a drive
  • Smoke from the engine bay at idle
  • Oil wet edges along the top of the engine
  • Misfire or engine warning light from oil in the spark plug wells
  • Low oil warning

How to check it

Where to look. Top of engine, valve cover

With the engine cover off, look along the joint between the plastic valve cover and the cylinder head, and down the exhaust side, for wet oil or baked-on residue. Smell for burning oil after the test drive and watch for smoke at idle. Ask whether the valve cover has been replaced and when. If a workshop inspection is possible: pull an ignition coil and check the spark plug well for oil, and check the PCV valve in the cover.

Parts involved: Rocker / valve cover, Turbocharger.

What it costs to put right

≈A$830 to ≈A$2,020 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

  • “Has the valve cover or its gasket been replaced?”
  • “Have you noticed a burning oil smell or smoke?”
  • “Has it had misfires or ignition coil replacements?”

Now check the BMW 3 Series you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car still has money owing on it, has been written off or reported stolen, what kms it showed in past sale ads, whether it has had accident repair claims and what it is worth today. That comes from the official records for that plate. Enter the plate and its state for the A$17.90 Vehicle Check, or the full history from A$24.99.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

BMW 3 Series buyer questions

Is valve cover gasket leak and cracked plastic valve cover (3.0 n55 turbo petrol, 335i) serious on a BMW 3 Series?

We rate it major and common on the BMW 3 Series. A leaking valve cover gasket, or a cracked plastic valve cover with its built-in PCV valve, is a known issue on the 3.0 N55 turbo petrol six in the 335i. Heat cycling hardens the gasket and can crack the plastic cover, so oil seeps out and can drip onto the hot exhaust side. Look for a burning oil smell, smoke from the engine bay and, in worse cases, oil in the spark plug wells that causes misfires. The usual fix is a new valve cover with its gasket, which is a long labour job.

How much does it cost to fix on a BMW 3 Series?

≈A$830 to ≈A$2,020 at independent workshop rates, shown as an approximate guide in Australian dollars. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which BMW 3 Series years are affected?

Our research records this fault on the 2010–2015 BMW 3 Series. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

With the engine cover off, look along the joint between the plastic valve cover and the cylinder head, and down the exhaust side, for wet oil or baked-on residue. Smell for burning oil after the test drive and watch for smoke at idle. Ask whether the valve cover has been replaced and when. If a workshop inspection is possible: pull an ignition coil and check the spark plug well for oil, and check the PCV valve in the cover. Look here: Top of engine, valve cover