The Porsche 928, introduced in 1978, remains one of the most unique and sought-after grand tourers in Porsche’s history. With its front-mounted V8 engine, advanced engineering, and luxurious interior, it was designed to be the ultimate sports-luxury coupe. However, as with any classic car, the 928 has its share of mechanical and electrical issues that owners should be aware of.
Understanding the most common Porsche 928 problems and knowing how to prevent or fix them can help enthusiasts keep their vehicles in peak condition for years to come. This guide covers frequent issues, their causes, and the best solutions to ensure your Porsche 928 remains a joy to drive.
1. Electrical Problems: The 928’s Most Notorious Issue
One of the biggest challenges 928 owners face is electrical system failures. Early models, in particular, had complex wiring harnesses, which can degrade over time.
Common Electrical Issues:
- Failing relays and fuses – The 928 relies heavily on electrical relays, which can wear out and cause intermittent issues.
- Dashboard gauge malfunctions – Speedometers, fuel gauges, and tachometers may stop working due to faulty wiring or corroded connections.
- Power window and sunroof failures – Motorized components can fail due to worn-out motors or damaged wiring.
Fixes & Prevention:
✔️ Inspect and replace faulty relays and fuses regularly.
✔️ Clean and secure all ground connections to prevent electrical shorts.
✔️ Upgrade to modern wiring harnesses if the factory setup is deteriorating.
2. Timing Belt Failures: A Costly but Preventable Issue
The timing belt is one of the most critical components in a Porsche 928 engine. A timing belt failure can result in catastrophic engine damage, making regular replacements essential.
Signs of a Worn Timing Belt:
- Squealing or ticking noises from the engine
- Rough idling or misfires
- Engine stalling or failure to start
Fixes & Prevention:
✔️ Replace the timing belt every 45,000–50,000 miles to avoid unexpected failure.
✔️ Replace the water pump at the same time, as a failing pump can damage the timing belt.
✔️ Use high-quality OEM belts to ensure durability and reliability.
3. Coolant Leaks & Overheating Issues
The 928’s cooling system is essential for maintaining optimal engine temperature, but leaks and overheating problems are common, especially in older models.
Common Cooling System Problems:
- Radiator leaks – Old radiators can develop cracks, causing coolant loss.
- Failing water pumps – A bad water pump can lead to overheating and potential engine damage.
- Clogged coolant hoses – Aging hoses can restrict coolant flow, leading to temperature fluctuations.
Fixes & Prevention:
✔️ Regularly inspect coolant levels and look for leaks under the car.
✔️ Replace old radiators and water pumps every 60,000–80,000 miles.
✔️ Flush and replace coolant every 2-3 years to prevent buildup and corrosion.
4. Fuel Injector Issues: Reduced Performance & Efficiency
Fuel injectors play a vital role in delivering the right mix of fuel and air for combustion. Over time, 928 fuel injectors can become clogged or fail, leading to poor performance and fuel inefficiency.
Symptoms of Fuel Injector Problems:
- Engine misfires or hesitation during acceleration
- Rough idling or stalling
- Black smoke from the exhaust (indicating a rich fuel mixture)
Fixes & Prevention:
✔️ Clean injectors regularly using fuel additives or professional ultrasonic cleaning.
✔️ Replace faulty injectors with high-quality OEM or upgraded versions.
✔️ Check fuel pressure regulators to ensure the proper flow of fuel.
5. Transmission Problems: Automatic vs. Manual Concerns
The 928 came with both automatic and manual transmissions, each with its own set of issues.
Common Automatic Transmission Problems:
- Slipping gears or delayed shifting due to worn-out clutch packs.
- Leaking transmission fluid, which can cause overheating and failure.
Common Manual Transmission Problems:
- Difficulty shifting due to worn synchronizers.
- Clutch wear from aggressive driving.
Fixes & Prevention:
✔️ Change transmission fluid every 30,000–50,000 miles.
✔️ Inspect for leaks regularly and address them early.
✔️ Upgrade to a performance clutch if planning to enhance power output.
6. Suspension & Steering Wear: Maintaining a Smooth Ride
As a grand tourer, the 928 was built for comfort and handling, but worn suspension components can impact ride quality.
Common Suspension & Steering Issues:
- Worn-out control arms and bushings lead to a loose, unstable ride.
- Leaking power steering fluid causes heavier steering effort.
- Sagging suspension affects cornering ability.
Fixes & Prevention:
✔️ Replace control arm bushings with polyurethane upgrades.
✔️ Flush and replace power steering fluid regularly.
✔️ Upgrade to adjustable coilovers for improved handling.
7. Brake System Maintenance: Ensuring Stopping Power
With more power comes the need for better stopping performance. The 928’s braking system requires regular maintenance to remain effective.
Common Brake Issues:
- Warped brake rotors cause vibrations during braking.
- Soft brake pedal feel due to air in the brake lines.
- Worn brake pads reduce stopping efficiency.
Fixes & Prevention:
✔️ Upgrade to drilled or slotted rotors for better heat dissipation.
✔️ Flush brake fluid every 2 years to prevent air bubbles.
✔️ Use high-performance brake pads for better grip and longevity.
Final Thoughts: Keeping Your Porsche 928 in Top Shape
The Porsche 928 is a timeless machine, but like any classic car, it requires proactive maintenance to stay roadworthy. By addressing common problems early and using quality parts and expert repairs, owners can extend the life of their 928 and enjoy its V8 power for years to come.
Key Takeaways:
✔️ Electrical issues? Inspect relays and wiring regularly.
✔️ Timing belt concerns? Replace every 45,000–50,000 miles.
✔️ Coolant leaks? Maintain the radiator and water pump.
✔️ Fuel injector failures? Clean or replace injectors as needed.
✔️ Transmission troubles? Change fluid and check for leaks.
✔️ Suspension wear? Upgrade bushings and shocks.
✔️ Braking problems? Use high-performance rotors and pads.
With proper care, a Porsche 928 can be both a reliable and rewarding classic car to own, ensuring you get the most out of your investment and driving experience. 🚗💨
Do you own a Porsche 928? What challenges have you faced? Let us know in the comments!
Owning a Porsche 928 is an immensely rewarding experience, but keeping it running at peak performance requires proactive maintenance and expert attention to common problem areas. Whether you’re preventing timing belt failures, addressing electrical gremlins, or upgrading your braking system, staying ahead of potential issues ensures that your 928 remains a powerful, reliable grand tourer for years to come.
Many of the 928’s known challenges—from fuel injector wear to suspension degradation—can be mitigated or completely avoided with regular servicing by a specialist who truly understands these V8-powered machines. With the right care, a well-maintained 928 isn’t just a pleasure to drive—it’s a classic that will continue to appreciate in value and performance.
Thank you for taking the time with me to learn more about what Don Fenton, the Porsche 928 whisperer, can do for you.
Sincerely,
Don Fenton
(AKA) 928 Done Right
For expert Porsche 928 repairs, maintenance, or restoration in the greater Austin area (or beyond), contact your premiere 928 mechanic, Don Fenton, AKA Mr. 928 Done Right – Porsche 928 repairs and restoration of Austin, because Don ensures any repairs get Done Right the first time!
📞 Call us now for a free estimate! (737) 900-8179
🌐 Visit us at www.928DoneRight.com
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