A Guide to the Engine Valve Cover Gasket Set for the 2015-2020 BMW M4
Understanding the common leaks and failures of the S55 engine's valve cover is key to a lasting repair.
- A squealing noise means the entire valve cover assembly must be replaced to fix the integrated PCV valve.
- Due to the high labor cost, using a cheap aftermarket part is risky; a Genuine BMW part is strongly recommended to avoid repeat repairs.
- The plastic valve cover can warp, so replacing only the gasket often results in a continued leak.
- Ignoring a failed PCV valve can lead to much more expensive engine seal failures.
Is Your M4 Leaking or Squealing?
The S55 engine in the 2015-2020 BMW M4 is a high-performance unit that runs hot, which puts stress on seals and gaskets. Over time, the rubber valve cover gasket can become hard and brittle from constant heat cycles, causing it to lose its seal. This is a common issue on many BMW engines. However, on the S55, there are two distinct types of failure to watch for: a simple gasket leak and a more serious PCV valve failure.
Symptoms of a Failing Valve Cover Gasket
When the gasket itself fails, oil will begin to seep out. Because of the engine's design, the leak is most often seen on the passenger (exhaust) side. Common symptoms include:
- Burning Oil Smell: This is the most common first sign. Oil drips onto the hot exhaust manifold and burns off, with the smell often entering the cabin when you're stopped.
- Visible Smoke: You may see smoke or vapor rising from the engine bay when the car is stopped and at operating temperature.
- Oil on the Engine: A visual inspection will show fresh, wet oil residue on the side of the engine block below the valve cover.
- Engine Misfires: If the leak is severe, oil can seep into the spark plug tubes, fouling the spark plugs and causing a rough idle or check engine light.
Watch Out for PCV Failure
A loud, high-pitched squeal or whistle from the engine at idle is a sign of a different problem. This noise indicates the diaphragm inside the integrated PCV valve has ruptured. This creates excessive vacuum in the engine and, if ignored, can damage other expensive seals, like the rear main seal—a much more costly repair. This squealing noise requires the replacement of the entire valve cover assembly.
Choosing the Right Aftermarket Gasket Set
Replacing the valve cover on an M4 is a labor-intensive job that requires removing strut braces, the charge air cooler, and the fuel rail. Because the labor cost is high, choosing a quality part is critical to avoid doing the job a second time. The plastic valve cover itself can also warp over time, meaning a new gasket on a warped cover won't seal properly. For this reason, most experienced technicians recommend replacing the entire valve cover assembly.
Brand Quality Tiers
When shopping for a replacement, you'll find several options:
- Premium (Recommended): A Genuine BMW valve cover assembly is the safest choice. While it is the most expensive option, its quality ensures a proper fit and a long-lasting repair, which is important for a job this complex.
- Mid-Grade (Use with Caution): Brands like Victor Gaskets (Victor Reinz) and Elwis (Elring) are known OEM suppliers for many German auto parts. Their gaskets are generally considered reliable. However, reviews on their complete valve cover assemblies are mixed. These can be a cost-saving option, but they carry some risk compared to the genuine part.
- Economy (Not Recommended): Brands like URO Parts are widely reported by BMW communities to have fitment and quality control issues. Given the high labor cost of this specific repair, using a low-cost part that might fail prematurely is a significant risk.
Pro Tip: Due to the high labor costs ($1,200+), spending more on a Genuine BMW valve cover assembly is often cheaper in the long run than risking a premature failure with an aftermarket part and paying for the labor twice.
Cost of Replacing an M4 Valve Cover Gasket Set
| Part Type | Price Range |
|---|---|
| New Aftermarket Gasket Set Only | $24.78 - $83.63 |
| New Aftermarket Valve Cover Assembly | $220 - $380 |
| New OEM Valve Cover Assembly | $700 - $780 |
| Shop Labor | $1,233 - $1,809 |
Frequently Asked Questions
Can I just replace the gasket instead of the whole valve cover?
You can, but it is not recommended for the S55 engine. The original plastic valve cover is known to warp from heat, and a new gasket on a warped surface will not create a proper seal, leading to continued leaks. Furthermore, if your issue is the common squealing noise, the problem is the integrated PCV valve, which can only be fixed by replacing the entire cover assembly.
What happens if I ignore a leaking valve cover gasket?
A minor leak can cause a drop in engine oil, a messy engine bay, and a persistent burning oil smell. A more severe leak can foul spark plugs, causing misfires. If the leak is from a failed PCV valve (the squealing noise), ignoring it can lead to catastrophic failure of other engine seals, like the rear main seal, which is an extremely expensive repair.
Is the replacement something I can do myself (DIY)?
This is considered a difficult (4/5) and time-consuming (approx. 6 hours) job. It requires the removal of the carbon fiber strut brace, the charge air cooler, ignition coils, and the high-pressure fuel rail. While possible for a very experienced home mechanic with the right tools, it is a complex procedure that most owners will leave to a professional shop.
Are aftermarket aluminum valve covers a good upgrade?
Aftermarket aluminum valve covers are available and offer increased durability, especially for cars that see track use or run higher boost levels. They resist cracking and warping better than the stock plastic cover. For a daily driven M4, a new OEM plastic cover is perfectly adequate, but an aluminum cover can be considered a long-term durability upgrade if you are willing to spend more.
Technical Specifications
OEM Part Numbers: 11127846359
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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.
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