With experience specializing in European vehicles, M&R Auto understands what it takes to keep BMW 4 Series coupes and convertibles performing smoothly long-term. Our ASE-certified technicians combine deep technical knowledge of these advanced vehicles with state-of-the-art diagnostic scanners and equipment to resolve issues small and large.
In this comprehensive guide, we’ll explore symptoms, causes, and fixes for the most common problems reported by 4 Series owners. Review the issues and recommended repairs discussed below. Reach out to schedule an inspection or service today if noticing any similar symptoms in your luxury performance vehicle.
Tracking Down Engine Oil Leaks
Oil leaks seem inevitable in many aging vehicles, but that doesn’t mean driving around with an occasional drip here or there is acceptable, especially for a marque like BMW. Left unchecked, even small leaks can lead to unsightly stains in your driveway, reduced engine performance from low oil levels, and exponential increases in oil consumption over time. In 4 Series vehicles, particularly model years 2014-2018, common leak points include the valve cover gasket, oil filter housing gasket, and main oil pan gasket.
Symptoms of Engine Oil Leaks:
- Visible oil dripping underneath vehicle
- Low oil level warnings illuminated on dashboard
- Blue-tinted exhaust smoke at cold startup
- Burning oil odors from engine bay
Our technicians thoroughly diagnose leaks at M&R Auto through visual inspection first, followed by oil pressure testing that can pinpoint elusive seepage past seals and gaskets. We then use only OEM or OE-equivalent replacement gaskets to permanently cure leaks in a lasting way. This keeps your 4 Series engine healthy for the long run.
Keeping Your Cool: Preventing Overheating
BMW’s renowned driving dynamics depend on impeccable engine cooling capability. Overheating not only causes immediate breakdowns, but sustained operation at excess temperatures accelerates future gasket and seal deterioration. Models from 2014-2019 seem most prone to developing cooling system leaks and component failures like water pump impeller cracks or stuck thermostats preventing flow.
Warning Signs of Cooling Issues:
- High engine temp warning light illumination
- Visible coolant puddles underneath car
- Sweet, chemical odor from overflow reservoir
- Reduced interior heater output
Using pressure testing methods, our techs can identify very small leaks and pinpoint their location. We then perform inspections of components like water pumps, thermostats and radiator caps for correct operation. Any parts found defective get replaced with new OEM components before performing a full system flush. This keeps your 4 Series running cool for years of driving enjoyment.
Electrical Gremlins: Chasing Down Faults
With complex electronics governing everything from engine performance to lighting, entertainment, and comfort features, BMW 4 Series vehicles have plenty of opportunities for failures and faults to arise. Intermittent issues seem especially tricky to resolve. Having access to advanced diagnostics for scan tool fault code analysis and software flashing gives our technicians an advantage when electrical issues strike models from 2014-2020.
Electrical Fault Symptoms:
- Inaccurate or non-functional gauges and displays
- Battery draining overnight
- Error messages in the iDrive display
- Climate control malfunctions
- Power windows or sunroof inoperative
Through battery load testing, targeted circuit diagnosis, and BMW-specific software updates, we can get to the bottom of electrical gremlins and ghosts in the machine. Let us save you the headaches so you can better enjoy the latest amenities these ultimate driving machines offer.
Handling Woes: Replacing Worn Components
The BMW 4 Series made its name on curvy backroads and track days showcasing incredible grip and balance through the corners. But over time on original suspension and steering components, that pinpoint precision gives way to sloppy handling and uneven tire wear as parts like control arm bushings, tie rods, struts, and ball joints wear past viable tolerances. Starting mainly in the 5th model year, 2014-2021 cars eventually need these service items addressed.
Signs of Worn Suspension Parts:
- Vehicle pulls left or right on straight roads
- Excessive vibration felt through steering wheel
- Clunking noises over large bumps
- Exaggerated body lean on entrance/exit ramps
With an alignment check and thorough inspection of all suspension and steering components, we can advise which parts need replacement or bushings injected with fresh rubber to tighten things back up. This restores confidence and control when pushing your 4 Series through the winding roads it was made for.
Braking Confidence: Eliminating Vibrations
BMW is renowned for its powerful yet precise braking capabilities. But even these sophisticated systems encounter issues like warped rotors triggering pedal pulsations and vibrations that rob drivers of smooth, confident stops. Pad and rotor wear also accelerate on track days and performance driving. Across model years 2014-2019, we see common issues needing attention to maintain safety and control.
Symptoms of Braking System Issues:
- High pitched squealing when braking
- Steering wheel shudder under hard braking
- Reduced rotor thickness and pad material
- Uneven pad deposits on rotors
M&R Auto’s brake specialists address these issues through replacement of any excessively worn pads or rotors that fall out of minimum thickness specifications. For warped rotors causing pulsations, our on-car brake lathe resurfacing service can smoothly machine away thickness variations so new pads bed in evenly across the rotor. This permanently eliminates shudder and vibration issues for confident braking performance all around.
Turbocharger Repairs: Maintaining Boost
As a signature of the BMW driving experience, the forceful acceleration surge of the 4 Series turbocharged power plants always puts a smile on enthusiasts’ faces. But over tens of thousands of miles, some 2014-2020 models encounter issues like oil leaks at turbo seals, worn bearings allowing excessive shaft play, and operating delays from the variable vane mechanisms that optimize boost response. Left alone, these issues can rob engines of their characteristic punch.
Turbocharger Problem Indicators:
- Increased turbo lag and reduced top-end power
- Oil leaks around turbo center section
- Metallic grinding noises at higher RPMs
- Excessive bluish smoke from tailpipe
Using visual inspection and boost pressure measurements, our technicians can accurately diagnose turbo system issues. We advise replacement or professional rebuild services for components found to be damaged or excessively worn. This restores the quick spool up and forceful top end power 4 Series owners expect while maintaining fuel efficiency and emissions compliance.
Transmission Service: Preventing Leaks
Sealing components inside BMW’s advanced 8-speed automatic transmissions inevitably wear after tens of thousand miles of use, with some 2014-2019 models developing leaks that will only get worse over time if left alone. Owners may notice spots accumulating underneath on their garage floor. Even small leaks that seem harmless should get diagnosed right away before resulting contamination and slippage issues snowball.
Transmission Leak Symptoms:
- Red fluid dripping underneath transmission bell housing
- Burning odor from transmission fluid
- Delayed gear engagement when accelerating
- Slipping between gears under heavy throttle
Through visual inspection and diagnostic scans, we can accurately locate the source of transmission leaks and recommend resealing procedures or replacement of internal seals and gaskets as applicable. This keeps ZF-sourced 8HP transmissions running cleanly and efficiently. We also advise periodic fluid changes to maintain protection against overheating and wear.
Trust M&R Auto for Your 4 Series Repairs
Our team lives, eats and breathes BMW repairs, maintenance and performance upgrades. We apply our passion at M&R Auto to solve mechanical issues, big or small, that stand between 4 Series owners and driving enjoyment. Whether you reside right in Palo Alto or the greater Bay Area, our shop offers convenient service with immaculate attention to detail.
Contact us anytime for questions regarding your 4 Series maintenance or repairs. We look forward to discussing the issues above or walking through any other symptoms you’ve noticed with your vehicle’s operation. With preventative maintenance and prompt attention to warning signs, these BMWs will provide a smooth, exhilarating driving experience for years to come.
