The 5.7L Hemi engine, a powerhouse found in many Chrysler, Dodge, and Jeep vehicles, has earned a reputation for its impressive performance and robust design. However, like any engine, the 5.7 Hemi isn't immune to its share of common problems. Understanding these issues can help you keep your Hemi-powered ride running smoothly and avoid costly repairs down the road.

So, What's the Deal With These Hemis? Let's Talk Trouble Spots

The 5.7 Hemi, while generally reliable, has some known weaknesses. Let's dive into the most frequently reported issues and what you can do about them.

The Dreaded "Hemi Tick": Is It a Ticking Time Bomb?

One of the most talked-about – and feared – issues with the 5.7 Hemi is the infamous "Hemi Tick." This is a distinct ticking or tapping sound that usually becomes noticeable at idle or low RPMs. The sound often intensifies as the engine warms up.

  • What Causes the Tick? The exact cause can vary, but the most common culprits include:

    • Exhaust Manifold Bolts: These bolts are prone to breaking or loosening, creating a small exhaust leak. The escaping exhaust gas produces a ticking sound. This is arguably the most common cause and often the easiest to fix.
    • Lifter Failure: In some cases, the lifters (which connect the camshaft to the valves) can fail. This can lead to excessive play and a noticeable ticking sound. This is a more serious issue than exhaust manifold bolts and requires more extensive repair.
    • Piston Slap: This occurs when the piston moves slightly within the cylinder bore, creating a knocking sound. While less common than exhaust leaks or lifter issues, it can happen.
    • Oil Starvation: In rare cases, inadequate lubrication can cause the ticking.

  • How Do I Diagnose It?

    1. Listen Carefully: Try to pinpoint the location of the tick. Is it coming from the top of the engine, the exhaust manifolds, or somewhere else?
    2. Visual Inspection: Check the exhaust manifold bolts for any signs of breakage or loosening. Look for black soot around the manifold, which indicates an exhaust leak.
    3. Stethoscope (Optional): Using a mechanic's stethoscope can help you isolate the source of the tick.
    4. Oil Pressure Check: Ensure your oil pressure is within the normal range. Low oil pressure could indicate a lubrication problem.

  • What Can I Do About It?

    • Exhaust Manifold Repair: If the tick is caused by broken or loose exhaust manifold bolts, replace the bolts or repair the manifold. Many aftermarket solutions are available that address the weaknesses of the original design.
    • Lifter Replacement: If the tick is due to lifter failure, the lifters will need to be replaced. This is a more involved repair that often requires removing the cylinder heads. Consider replacing the camshaft as well, as wear on the camshaft lobes can contribute to lifter failure.
    • Oil Change: Ensure you're using the correct type and viscosity of oil for your Hemi engine. Regular oil changes are crucial for maintaining engine health.
    • Seek Professional Help: If you're unsure about the cause of the tick or uncomfortable performing the repairs yourself, consult a qualified mechanic.

Important Note: Not all ticking sounds indicate a serious problem. Some Hemis simply make more noise than others. However, it's always best to investigate any unusual sounds to prevent potential damage.

MDS (Multiple Displacement System) Issues: When Four Cylinders Aren't Enough

The 5.7 Hemi often comes equipped with the Multiple Displacement System (MDS), which shuts down four cylinders during light load conditions to improve fuel economy. While a clever idea, MDS can sometimes cause problems.

  • What Kind of Problems?

    • Rough Idle or Stalling: MDS can cause a rough idle or even stalling, especially when transitioning between eight-cylinder and four-cylinder mode.
    • Hesitation or Lag: You might experience hesitation or lag when accelerating, as the engine switches back to eight-cylinder mode.
    • Increased Oil Consumption: Some owners have reported increased oil consumption with MDS-equipped engines.
    • Lifter Failure (Again!): The MDS system uses solenoids to activate and deactivate the lifters on the cylinders being shut down. These solenoids can sometimes fail, leading to lifter failure, particularly on the cylinders that are deactivated. This is because the lifters on these cylinders are subject to different wear patterns.

  • How Do I Know If It's MDS?

    • Listen for a Change in Engine Note: When MDS engages, you might notice a subtle change in the engine's sound.
    • Monitor Fuel Economy: If your fuel economy is significantly worse than expected, MDS might not be functioning correctly.
    • Check for Diagnostic Trouble Codes (DTCs): A diagnostic scan tool can reveal any DTCs related to the MDS system.

  • What Can I Do About It?

    • Disable MDS: Many tuners and aftermarket devices can disable the MDS system. This will eliminate the issues associated with MDS but will also reduce fuel economy.
    • MDS Solenoid Replacement: If the problem is a faulty MDS solenoid, replacing the solenoid might resolve the issue.
    • Regular Oil Changes: Maintaining clean oil is crucial for the proper functioning of the MDS system.
    • Consider a Delete Kit: If you're experiencing persistent problems with MDS, you might consider a complete MDS delete kit. This involves replacing the MDS lifters and solenoids with non-MDS components.

Oil Leaks: Spotting and Stopping the Drips

Oil leaks are a common issue with many engines, and the 5.7 Hemi is no exception.

  • Where Are They Likely to Occur?

    • Valve Cover Gaskets: These gaskets can dry out and crack over time, leading to oil leaks.
    • Oil Pan Gasket: The oil pan gasket can also leak, especially on older engines.
    • Rear Main Seal: This seal prevents oil from leaking out of the rear of the engine. A leaking rear main seal is a more involved repair.
    • Oil Filter Adapter: The oil filter adapter can sometimes leak, especially if the gasket is damaged.

  • How Do I Find the Leak?

    • Visual Inspection: Look for oil stains on the engine, under the vehicle, or on the ground.
    • Clean the Engine: Cleaning the engine can make it easier to spot the source of the leak.
    • Use a UV Dye: Adding a UV dye to the oil and using a UV light can help you pinpoint the leak.

  • What Can I Do About It?

    • Replace the Gasket or Seal: The most common solution is to replace the leaking gasket or seal.
    • Tighten Loose Bolts: Sometimes, simply tightening loose bolts can stop a leak.
    • Use a Sealant: In some cases, using a sealant along with a new gasket can help prevent future leaks.

Spark Plug Issues: Misfires and Rough Running

The 5.7 Hemi uses two spark plugs per cylinder, which provides more efficient combustion. However, this also means that there are twice as many spark plugs to potentially cause problems.

  • What Kind of Problems?

    • Misfires: Worn or fouled spark plugs can cause misfires, leading to rough running and reduced performance.
    • Difficulty Starting: Bad spark plugs can make it difficult to start the engine.
    • Reduced Fuel Economy: Misfires can also reduce fuel economy.

  • How Do I Diagnose It?

    • Check for Diagnostic Trouble Codes (DTCs): A diagnostic scan tool can reveal any DTCs related to misfires.
    • Inspect the Spark Plugs: Remove the spark plugs and inspect them for wear, fouling, or damage.

  • What Can I Do About It?

    • Replace the Spark Plugs: The most common solution is to replace the spark plugs with new ones. Use the correct type of spark plugs recommended for your Hemi engine.
    • Check the Spark Plug Wires: Ensure the spark plug wires are in good condition and properly connected.

Sensor Failures: Keeping the Engine Running Smoothly

Like all modern engines, the 5.7 Hemi relies on a variety of sensors to monitor engine performance. When these sensors fail, it can cause various problems.

  • Which Sensors Are Prone to Failure?

    • Oxygen (O2) Sensors: These sensors monitor the oxygen content in the exhaust gas and help the engine control unit (ECU) adjust the air-fuel mixture.
    • Mass Air Flow (MAF) Sensor: This sensor measures the amount of air entering the engine.
    • Crankshaft Position Sensor: This sensor monitors the position of the crankshaft.
    • Camshaft Position Sensor: This sensor monitors the position of the camshaft.

  • What Are the Symptoms of a Sensor Failure?

    • Check Engine Light: A sensor failure will often trigger the check engine light.
    • Poor Performance: The engine might run poorly, hesitate, or lack power.
    • Reduced Fuel Economy: Sensor failures can also reduce fuel economy.
    • Difficulty Starting: In some cases, a sensor failure can make it difficult to start the engine.

  • How Do I Diagnose It?

    • Check for Diagnostic Trouble Codes (DTCs): A diagnostic scan tool can reveal any DTCs related to sensor failures.
    • Inspect the Sensors: Visually inspect the sensors for damage or corrosion.

  • What Can I Do About It?

    • Replace the Sensor: The most common solution is to replace the faulty sensor with a new one.

Frequently Asked Questions (FAQ)

  • What oil type should I use in my 5.7 Hemi? Refer to your owner's manual for the recommended oil type and viscosity. Many owners use 5W-20 or 5W-30 synthetic oil.
  • How often should I change the oil in my 5.7 Hemi? The recommended oil change interval is typically every 6,000 miles or 6 months, but it's best to follow your owner's manual. More frequent changes are beneficial under severe driving conditions.
  • Is the Hemi tick a serious problem? It depends on the cause. Exhaust manifold leaks are common and relatively easy to fix, while lifter failure is a more serious issue.
  • Can I disable MDS without affecting performance? Yes, disabling MDS can often improve performance by eliminating the lag associated with cylinder deactivation. However, it will reduce fuel economy.
  • How long do 5.7 Hemi engines typically last? With proper maintenance, a 5.7 Hemi engine can last for 200,000 miles or more. Regular oil changes and addressing problems promptly are key to longevity.

Wrapping Things Up: Keeping Your Hemi Happy

While the 5.7 Hemi has its quirks, understanding these common problems can empower you to keep your engine running smoothly and avoid costly repairs. By being proactive with maintenance, addressing issues promptly, and seeking professional help when needed, you can enjoy the power and performance of your Hemi for years to come. Remember to listen to your engine!