2008-2015 Smart Fortwo Flywheel Failure: Noises, Diagnosis, and Replacement Guide
Understand the common failure symptoms of the Smart Fortwo flywheel, how to inspect a used part, and why this repair is a major undertaking.
- The 2008-2015 Smart Fortwo uses a flywheel with an automated manual transmission, not a flexplate.
- Replacement is a major job requiring engine and transmission removal, making it a 5/5 difficulty.
- It is critical to replace the clutch, pressure plate, and release bearing at the same time as the flywheel.
- When buying a used flywheel, inspect the ring gear teeth for damage and the friction surface for heat spots and cracks.
Symptoms of a Failing Flywheel
A failing flywheel in a Smart Fortwo can produce several distinct symptoms. Because the engine is in the rear, some noises and vibrations may be less obvious than in a front-engine car.
- Rattling or Knocking at Idle: The most common symptom is a metallic rattling or knocking sound when the car is in neutral and idling. This noise often disappears or changes when you start to accelerate. This can be caused by worn or broken internal springs in the dual-mass flywheel design.
- Vibrations: You might feel unusual vibrations through the floor of the car or the clutch pedal (if you could feel it). These vibrations can occur at idle or when accelerating. If the flywheel is warped or out of balance, it can cause significant shaking.
- Clutch Chatter or Shudder: When engaging the clutch from a stop, you may experience a chattering or shuddering sensation. This can be due to heat spots or an uneven surface on the flywheel.
- Difficulty Starting: If the teeth on the flywheel's ring gear are damaged or broken, the starter motor may struggle to engage, resulting in a grinding noise or failure to crank the engine.
- Burning Smell: A persistent burning smell can indicate a slipping clutch, which may be caused by a glazed or warped flywheel surface that prevents the clutch disc from gripping properly.
Known Issues, Recalls, and TSBs
While there are no specific recalls or Technical Service Bulletins (TSBs) directly targeting the flywheel for the 2008-2015 Smart Fortwo, some related issues are worth noting.
- NHTSA Recall 18V-273: This recall was issued for 2008-2009 models due to the engine compartment insulation mat deforming and potentially contacting hot exhaust components, creating a fire risk. While not a flywheel issue, it involves the same area of the vehicle and highlights the high temperatures in the compact engine bay.
- NHTSA Engine Fire Investigation: In late 2016, the NHTSA opened a preliminary investigation into engine fires in 2008-2009 models after receiving multiple complaints. This investigation ultimately led to the insulation mat recall.
- Clutch Actuator Failure: The clutch actuator is a known weak point in this system. While a separate part, its failure can sometimes be misdiagnosed as a clutch or flywheel problem, or vice-versa. It's common for mechanics to inspect the actuator when diagnosing any transmission-related complaints.
Buying a Used Flywheel: What to Check
Since replacing the flywheel is a labor-intensive job, it's crucial to select a good quality used part. A recycled OEM flywheel is often a better choice than a cheap aftermarket alternative, as it was designed and balanced specifically for the Smart's engine.
- Inspect the Ring Gear: Carefully examine all the teeth on the outer ring gear. Look for any that are chipped, broken, or excessively worn down. The starter motor needs a clean, complete set of teeth to work reliably.
- Check the Friction Surface: The flat, machined surface where the clutch disc makes contact should be smooth. Run your fingers over it to feel for grooves or ridges. Look for signs of overheating, such as blue or purple discoloration, and fine, web-like cracks (heat checking). Any of these are red flags.
- Look for Damage: Inspect the overall flywheel for any cracks, especially around the bolt holes in the center. Check for any signs of previous repairs or modifications.
- Verify Part Numbers: Ensure the part number on the used flywheel matches the required OEM number for your vehicle. The primary OEM part number is A1320300005 (or 1320300005).
Pro Tip: The flywheel is almost always replaced as part of a complete clutch job. It is highly recommended to replace the clutch disc, pressure plate, and release bearing at the same time as the flywheel. 🎬 Watch this video overview of a Smart Fortwo clutch and flywheel assembly replacement. The labor is the same, and installing a new flywheel with a worn clutch is a recipe for premature failure.
Replacement Difficulty and Cost
Replacing the flywheel on a 2008-2015 Smart Fortwo is a difficult and time-consuming job that requires removing the engine and transmission from the vehicle.
- Difficulty Rating: 5 out of 5 (Professional level)
- DIY Feasibility: Not recommended for beginners or those without a vehicle lift and engine hoist.
- Estimated Time: 8-12 hours
Warning: During installation, you must use new alignment dowels to ensure the flywheel is perfectly centered and balanced. Reusing old dowels can lead to severe vibrations and damage. The part number for these dowels is 0009914252.
Cost Comparison
The majority of the cost for this repair is labor. Because the labor is so high, it makes sense to use quality parts to avoid doing the job twice.
| Part/Service | Estimated Cost |
|---|---|
| New OEM Flywheel | $400 - $600+ |
| New Aftermarket Flywheel (LuK, Sachs) | $300 - $450 |
| Used OEM Flywheel | $75 - $200 |
| Complete Clutch Kit (Aftermarket) | $250 - $400 |
| Shop Labor for Clutch & Flywheel Replacement | $750 - $1,100+ |
| Total Professional Job (Used OEM Flywheel + New Clutch) | $1,100 - $1,700 |
| Total Professional Job (New OEM/Aftermarket Parts) | $2,600 - $3,100 |
Frequently Asked Questions (FAQ)
Can I just replace the flywheel and not the clutch?
It is strongly advised against. The cost of removing the engine and transmission is the largest part of the expense. Installing a new flywheel with a partially worn clutch disc and pressure plate will likely lead to another failure in the near future, forcing you to pay for the same labor all over again. Always replace the flywheel, clutch disc, pressure plate, and release bearing as a complete set.
Is a rattling noise at idle always a bad flywheel?
Not always, but it is a very common symptom. Other potential causes could be a loose exhaust heat shield or a problem with the clutch actuator. However, if the noise goes away when you press the accelerator, the flywheel is a primary suspect.
What is the difference between a flywheel and a flexplate?
A flywheel is used with a manual or automated-manual transmission and works with a clutch. It's thick and heavy to store rotational energy. A flexplate is used with a conventional automatic transmission and connects the engine to a torque converter. It is a thin, light piece of stamped steel and is not interchangeable with a flywheel.
Do I need any special tools for this job?
Yes. Besides a vehicle lift and engine hoist, you will need a set of Torx sockets, an engine support bar, and a clutch alignment tool. A half-inch socket extension can sometimes be used as a makeshift alignment tool on these models.
Helpful Videos
Technical Specifications
OEM Part Numbers: A1320300005 1320300005
Required Installation Hardware: Alignment Dowels (OEM Part # 0009914252)
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.
- Smart Fortwo: