2017-2022 BMW M760i Timing Cover: Diagnosing and Fixing N74 V12 Oil Leaks
A detailed guide to identifying common oil leaks from the lower timing cover on the 6.6L V12 engine, and what to look for when buying a used replacement.
- The primary failure is the gasket causing an oil leak, not the metal cover itself. This makes a verified, undamaged used OEM cover a smart purchase.
- Replacement is an expert-level job requiring 15-20+ hours of labor due to the extensive disassembly of the front of the V12 engine.
- Before diagnosing a timing cover leak, check for the simpler oil cooler line leak, which was subject to a recall on 2017-18 models (NHTSA 17V240000).
- When performing this repair, it is critical to also replace the front crankshaft seal, serpentine belts, and consider preventative replacement of the water pump and thermostat.
Symptoms of a Failing M760i Timing Cover
The timing cover itself is a very durable component. Failure almost always refers to the gaskets that seal it to the engine block. When these gaskets degrade, they allow oil to escape.
- Oil Leaks at the Front of the Engine: This is the most common symptom. You may notice drips of oil on the ground under the front of your engine. Often, the oil will run down the front of the engine and onto the plastic undertray, making the exact source difficult to pinpoint without inspection.
- Burning Oil Smell: If the leaking oil drips onto hot components like the exhaust manifolds, it will burn off, creating a distinct and unpleasant smell that can be noticeable inside and outside the car.
- Low Engine Oil Warning Light: A significant leak will cause the engine oil level to drop over time. This may trigger the low oil level or low oil pressure warning light on your dashboard. Running an engine with low oil can lead to catastrophic damage.
- Visible Oil Stains and Grime: Upon inspection, the front of the engine around the timing cover will be coated in a layer of oily grime. The leak often originates from the seams where the cover meets the engine block or cylinder heads.
Known Issues, Recalls, and TSBs
Oil Cooler Line Recall (Potential for Misdiagnosis)
Important: BMW issued a recall (NHTSA Campaign Number: 17V240000) for some 2017-2018 M760i models for engine oil cooler lines that could loosen and leak. This leak also occurs at the front of the vehicle and can drip oil onto the front brakes, increasing stopping distance. Before assuming you have a timing cover leak, it is crucial to have a technician inspect the oil cooler lines, as this was a known issue addressed by a safety recall.
As of early 2026, there are no specific recalls or widespread Technical Service Bulletins (TSBs) for the timing cover or its gaskets on the 2017-2022 BMW M760i. However, oil leaks from various gaskets, including the timing cover, are a well-documented issue across many BMW engine families over time. 🎬 Watch: Learn why BMWs are prone to these common oil leaks. The N74 V12, being a complex and high-heat engine, is susceptible to gasket degradation as it ages.
Buying a Used M760i Lower Timing Cover
Since the timing cover itself is a simple piece of cast aluminum, an undamaged used OEM part is an excellent way to save a significant amount of money. The failure point is almost always the disposable gasket, not the cover itself. Here’s what to check before buying.
Physical Inspection Checklist
- Check for Cracks: Carefully inspect the entire cover, especially around the bolt holes and corners, for any hairline cracks. A cracked cover is unusable.
- Inspect Sealing Surfaces: Run your finger along all the flat machined surfaces where the gaskets sit. They must be perfectly smooth and free of deep scratches, gouges, or corrosion pitting.
- Look for Warping: Place the cover on a known flat surface (like a piece of thick glass or a machinist's block) to check for any warping. It should sit perfectly flat without rocking. A warped cover will never seal properly.
- Verify Threaded Holes: If the cover has any threaded holes for mounting accessories, check to ensure the threads are clean and not stripped or damaged.
- Ignore Old Gaskets: Pay no attention to the condition of the old gaskets or seals left on the used part. They must always be replaced with new ones during installation.
Part Number Verification
Ensure the part you are buying is OEM number 11148620773. This number should be cast or stamped onto the part itself. This is the lower timing cover for the 6.6L V12 engine in the M760i. Do not confuse it with the upper timing covers.
Replacement Cost & Difficulty
Replacing the lower timing cover gasket on a BMW M760i is a complex, labor-intensive, and expensive job. It is not recommended for a DIY mechanic without extensive experience and access to specialized tools.
- Difficulty Rating: 5 out of 5 (Expert Level)
- Primary Reason for Difficulty: Access. A huge number of components must be removed to get to the cover, including the radiator and cooling fan, serpentine belts and tensioners, vibration damper, water pump, and numerous other accessories and brackets that are tightly packed into the V12 engine bay. The oil pan may also need to be at least partially removed to access the lower bolts.
Cost Breakdown
The majority of the cost for this repair is labor. Because the job is so involved, it's wise to replace other accessible service items at the same time.
Pro Tip: While the timing cover is off, it is highly recommended to also replace the front crankshaft seal, serpentine belts, and any idler or tensioner pulleys that show signs of wear. Since the cooling system must be drained, this is also the perfect time to replace the water pump and thermostat as a preventative measure.
| Part/Service | Estimated Cost |
|---|---|
| New OEM Lower Timing Cover | $450 - $650 |
| New Aftermarket Cover | Not commonly available |
| Used OEM Lower Timing Cover | $150 - $300 |
| Gasket & Seal Kit | $100 - $200 |
| Shop Labor | $2,500 - $4,000+ |
Labor costs can vary significantly based on shop rate and location. The V12 engine makes this job substantially more time-consuming than on a 6 or 8-cylinder model.
Frequently Asked Questions (FAQ)
Do I need to replace the whole timing cover or just the gasket?
In nearly all cases, you only need to replace the gaskets and seals. The metal timing cover should only be replaced if it is physically damaged, such as being cracked from an impact or severely corroded.
What other parts should I replace during a timing cover job?
At a minimum, you must replace all timing cover gaskets and the front crankshaft seal. It is strongly recommended to also replace the serpentine belts, coolant, and consider replacing the water pump, thermostat, and belt tensioners while you have easy access. This is known as "while you're in there" maintenance and can save you thousands in future labor costs.
Can a bad timing cover leak cause the engine to jump time?
It is highly unlikely. The cover's job is to seal the engine. A leak itself will not affect the mechanical timing. The only way it could be related is if the timing chain guides (which are inside the cover) break and a piece of the guide physically damages the cover, but this is a separate and much more severe failure.
Is this the upper or lower timing cover?
This part number, 11148620773, is for the lower timing cover section on the N74 V12 engine. The engine uses a multi-part cover system, and it's important to identify which section is leaking before ordering parts.
Helpful Videos
Technical Specifications
OEM Part Numbers: 11148620773
Material: Cast Aluminum. Location: Front of engine, lower section.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- BMW M760i xDrive:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Symptoms of a Failing M760i Timing Cover
- Known Issues, Recalls, and TSBs
- Oil Cooler Line Recall (Potential for Misdiagnosis)
- Buying a Used M760i Lower Timing Cover
- Physical Inspection Checklist
- Part Number Verification
- Replacement Cost & Difficulty
- Cost Breakdown
- Frequently Asked Questions (FAQ)
- 🎟️ Get 5% Off