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2017 340i Oil Leak - Valve Cover Gasket or OFHG? Burning Smell at 75k Miles

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Chris P. · rep 0 · May 25, 3:02 AM · 1 replies · solved · Question

Vehicle: 2017 BMW 340i xDrive (F30)

Hey everyone, I've got a 2017 BMW 340i (F30) with about 75,000 miles on it. Lately, I've been noticing a distinct burning oil smell, especially after the engine warms up and after driving for a bit. It's becoming quite noticeable.

I took a look under the hood and saw some oil residue. There's some around the valve cover, particularly towards the rear, and also a bit near the oil filter housing. It's not a huge puddle on the ground, but it's definitely enough to be concerning and causing the smell.

I know both the valve cover gasket (VCG) and the oil filter housing gasket (OFHG) are common failure points on these B58 engines. Has anyone dealt with this on their F30 340i around this mileage? What was your experience like in diagnosing which one it was?

I'm pretty handy and thinking about tackling this myself if it's not too complex. What special tools might I need for either job? Any tips or tricks for a DIY repair would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:02 AM

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ClearTheCode admin answer:

It sounds like you're dealing with very common oil leak issues for the B58 engine in your 2017 BMW 340i. Both the Valve Cover Gasket (VCG) and the Oil Filter Housing Gasket (OFHG) are known failure points due to heat cycling and material degradation over time.

Diagnosis & Causes:

  1. Valve Cover Gasket (VCG): Often manifests as oil pooling in the spark plug wells, leaking down the back of the engine, or dripping onto the exhaust manifold, causing a burning smell. A failing PCV valve, which is integrated into the valve cover on the B58, can also contribute to VCG leaks by creating excessive crankcase pressure. This leak typically doesn't trigger specific OBD-II codes unless it leads to misfires (P030x) from oil fouling spark plugs.
  2. Oil Filter Housing Gasket (OFHG): This leak usually appears on the front passenger side of the engine, often dripping onto the serpentine belt or accessory drive components, which can then spray oil around the engine bay and also cause a burning smell. It can also contaminate the belt, leading to squealing noises or premature wear.

Steps for DIY (if comfortable):

  • Visual Inspection: Clean the suspected areas thoroughly and then monitor for fresh leaks. A small inspection mirror and a bright flashlight can help identify the exact source. For OFHG, check for oil residue on the alternator and belt.
  • Smoke Test: If you have access to a smoke machine, a crankcase smoke test can help identify vacuum leaks, which often accompany VCG failures if the PCV system is compromised.

When to See a Shop:

  • If you're unsure about the precise leak source or lack the specialized tools (e.g., torque wrench, specific sockets for the valve cover bolts, or a vacuum pump for the OFHG bleed procedure). Both jobs require careful attention to detail and proper torque specifications to prevent re-leaks.
  • If the leak is severe, causing significant oil loss, or if you notice any performance issues like rough idling or misfires.
  • The VCG job is more involved, requiring removal of numerous components and careful reassembly. If you're not confident with complex engine work, a professional shop can ensure proper sealing and prevent further issues. Ignoring these leaks can lead to lower oil levels, potential damage to engine components, and environmental concerns.
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