The 5.7L Hemi engine, a powerhouse found in many Dodge, Chrysler, and Ram vehicles, has earned a reputation for its robust performance and satisfying growl. However, like any engine, it's not immune to certain issues. Understanding these common problems can help you proactively maintain your vehicle, potentially saving you time, money, and headaches down the road. Let's dive into the potential hiccups you might encounter with your 5.7 Hemi and how to keep it running smoothly.

The Dreaded Hemi Tick: What's That Noise?

One of the most frequently discussed issues with the 5.7 Hemi is the dreaded "Hemi tick." This distinctive ticking or tapping sound, often most noticeable at idle, can be alarming, but it doesn't always indicate imminent engine failure.

  • What causes it? The exact cause of the Hemi tick is still debated, but several factors are believed to contribute. These include:

    • Exhaust Manifold Bolts: A common culprit is broken exhaust manifold bolts. These bolts can break due to thermal expansion and contraction, causing exhaust leaks that sound like a tick.
    • Lifter Issues: Some theories point to the hydraulic lifters, particularly those associated with the Multi-Displacement System (MDS), as a potential source. Wear or oil starvation can lead to lifter noise.
    • Piston Slap: In some cases, the tick could be caused by piston slap, where the piston skirt makes contact with the cylinder wall. This is more common in engines with higher mileage.

  • Is it serious? The severity of the Hemi tick can vary. In many cases, it's just an annoyance and doesn't affect engine performance. However, if the tick is accompanied by other symptoms, such as a loss of power, rough idling, or check engine light, it's crucial to have it diagnosed by a qualified mechanic.

  • What can you do about it?

    • Check Exhaust Manifold Bolts: Inspect the exhaust manifold bolts for breakage. This is often the first and easiest thing to check.
    • Oil Change: Ensure you're using the correct oil type and viscosity recommended by the manufacturer. Regular oil changes are essential for engine health.
    • Listen Carefully: Try to pinpoint the location of the tick. This can help your mechanic narrow down the potential causes.
    • Seek Professional Advice: If the tick persists or worsens, consult a trusted mechanic experienced with Hemi engines. They can perform a thorough inspection and diagnose the problem accurately.

MDS (Multi-Displacement System) Problems: When Four Cylinders Aren't Enough

The 5.7 Hemi often incorporates the Multi-Displacement System (MDS), designed to improve fuel economy by deactivating four cylinders during light load conditions. While a clever idea, MDS can sometimes be a source of problems.

  • How MDS works: MDS uses solenoids to collapse the lifters on specific cylinders, effectively shutting them down. When more power is needed, the solenoids reactivate the lifters, and the engine returns to eight-cylinder mode.

  • Potential Issues:

    • Lifter Failure: MDS lifters are more complex than standard lifters and can be prone to failure. This can lead to misfires, rough idling, and the dreaded Hemi tick.
    • Solenoid Problems: The MDS solenoids themselves can fail, preventing the system from activating or deactivating cylinders correctly.
    • Oil Consumption: Some owners have reported increased oil consumption associated with MDS.

  • What can you do?

    • Regular Oil Changes: Keeping the oil clean and at the correct level is crucial for the proper functioning of MDS.
    • Consider an MDS Delete: If you're experiencing persistent MDS problems, you might consider an MDS delete kit. This involves replacing the MDS lifters with standard lifters and disabling the MDS system through tuning. While this will eliminate the fuel-saving benefits of MDS, it can improve engine reliability.
    • Monitor Performance: Pay attention to any changes in engine performance, such as rough idling or misfires, and address them promptly.

The Dreaded Camshaft and Lifter Failure

While not exclusive to the 5.7 Hemi, camshaft and lifter failures are a concern, particularly in higher-mileage engines. This is a serious issue that requires immediate attention.

  • What happens? Over time, the lobes on the camshaft can wear down, and the lifters can become damaged. This can result in reduced engine performance, misfires, and even engine damage.

  • Symptoms:

    • Rough Idling: A worn camshaft or lifters can cause the engine to idle roughly.
    • Misfires: Misfires are a common symptom of camshaft and lifter failure.
    • Loss of Power: You may notice a significant decrease in engine power.
    • Check Engine Light: The check engine light will likely illuminate, often with codes related to misfires or camshaft position.
    • Increased Engine Noise: A ticking or tapping sound may be present, which can be difficult to distinguish from the Hemi tick.

  • What to do:

    • Professional Diagnosis: If you suspect camshaft or lifter failure, it's essential to have your engine diagnosed by a qualified mechanic.
    • Replacement: The most common solution is to replace the camshaft and lifters. This is a significant repair that requires specialized tools and expertise.
    • Consider Upgrades: When replacing the camshaft, you might consider upgrading to a performance camshaft for improved power and torque.

Exhaust Manifold Leaks: A Noisy Problem

As mentioned earlier, exhaust manifold leaks are a common issue with the 5.7 Hemi, often caused by broken exhaust manifold bolts.

  • Why it happens: The exhaust manifold is subjected to extreme temperatures, and the bolts can weaken and break due to thermal cycling.

  • Symptoms:

    • Ticking Noise: A ticking or tapping noise, often most noticeable when the engine is cold.
    • Exhaust Smell: You may smell exhaust fumes inside the cabin.
    • Reduced Fuel Economy: Exhaust leaks can negatively affect fuel economy.
    • Poor Performance: Exhaust leaks can reduce engine performance, particularly at lower RPMs.

  • Fixing the Leak:

    • Bolt Replacement: The most common solution is to replace the broken exhaust manifold bolts. However, this can be challenging, as the broken bolts can be difficult to extract.
    • Manifold Replacement: In some cases, the exhaust manifold itself may be cracked or warped, requiring replacement.
    • Professional Repair: It's often best to have this repair done by a qualified mechanic, as they have the tools and expertise to extract broken bolts and ensure a proper seal.

Throttle Body Issues: Sticking and Sluggishness

The throttle body controls the amount of air entering the engine. Over time, it can become dirty or malfunction, leading to performance problems.

  • What can go wrong?

    • Carbon Buildup: Carbon deposits can accumulate on the throttle body, restricting airflow and causing the throttle plate to stick.
    • Sensor Malfunctions: The throttle position sensor (TPS) can fail, providing incorrect information to the engine control unit (ECU).

  • Symptoms:

    • Rough Idling: A dirty or malfunctioning throttle body can cause the engine to idle roughly.
    • Hesitation: You may experience hesitation when accelerating.
    • Stalling: In severe cases, the engine may stall.
    • Check Engine Light: The check engine light may illuminate, with codes related to the throttle body or TPS.

  • Troubleshooting:

    • Throttle Body Cleaning: Cleaning the throttle body with a throttle body cleaner can remove carbon deposits and improve performance.
    • TPS Replacement: If the TPS is faulty, it will need to be replaced.
    • Professional Diagnosis: If cleaning or replacing the TPS doesn't resolve the issue, it's best to have the throttle body professionally diagnosed.

Oil Leaks: Keeping Things Sealed

Oil leaks are a common nuisance in any engine, and the 5.7 Hemi is no exception.

  • Common Leak Locations:

    • Valve Cover Gaskets: The valve cover gaskets can leak over time, allowing oil to seep out.
    • Oil Pan Gasket: The oil pan gasket can also leak, particularly in older engines.
    • Rear Main Seal: The rear main seal, located at the rear of the engine, can leak, resulting in oil dripping from the bellhousing.

  • What to do:

    • Identify the Source: The first step is to identify the source of the leak.
    • Replace Gaskets/Seals: Replace the leaking gaskets or seals.
    • Check for Damage: Inspect the surrounding components for any damage that may be contributing to the leak.

Overheating: Keeping Your Cool

While less common than some other issues, overheating can be a serious problem that can cause significant engine damage.

  • Potential Causes:

    • Low Coolant: Low coolant levels can prevent the engine from cooling properly.
    • Faulty Thermostat: A faulty thermostat can prevent the engine from reaching its operating temperature or cause it to overheat.
    • Radiator Issues: A clogged or damaged radiator can restrict coolant flow and reduce cooling efficiency.
    • Water Pump Failure: A failing water pump can reduce coolant circulation, leading to overheating.

  • What to do:

    • Check Coolant Levels: Regularly check the coolant levels and top off as needed.
    • Inspect the Cooling System: Inspect the radiator, hoses, and water pump for any signs of leaks or damage.
    • Replace Faulty Components: Replace any faulty components, such as the thermostat or water pump.
    • Professional Diagnosis: If you suspect a serious overheating problem, it's best to have it diagnosed by a qualified mechanic.

Frequently Asked Questions

  • What's the best oil for a 5.7 Hemi?
    The manufacturer's recommended oil is typically 5W-20 or 5W-30 full synthetic. Always consult your owner's manual for the specific recommendation for your vehicle.

  • Is the Hemi tick normal?
    A slight Hemi tick is common and often doesn't indicate a serious problem, but a loud or persistent tick should be investigated.

  • How often should I change the oil in my 5.7 Hemi?
    Oil change intervals typically range from 5,000 to 7,500 miles, depending on driving conditions and oil type. Refer to your owner's manual for the recommended interval.

  • What is MDS, and is it reliable?
    MDS is a fuel-saving system that deactivates four cylinders during light load. While effective, it can be a source of lifter and solenoid problems.

  • Can I disable MDS?
    Yes, MDS can be disabled using an MDS delete kit, which involves replacing the MDS lifters and disabling the system through tuning.

Keeping Your Hemi Happy

The 5.7 Hemi is a powerful and capable engine, but like any engine, it requires proper maintenance and care. By being aware of these common problems and taking proactive steps to address them, you can keep your Hemi running smoothly for years to come. Addressing issues early can save you time, money, and the frustration of major repairs.