How to Remove the Intake Manifold on a 2020 Nissan Maxima

How to Fix Intake Manifold Replacement

For 2020 Nissan Maxima owners, addressing issues that require intake manifold removal is a significant repair that often stems from other problems like vacuum leaks or accessing hard-to-reach components. This guide synthesizes direct experiences from Maxima forums to help you understand the symptoms, diagnosis, and repair process. As one owner shared regarding a related repair, "Dude mentioned that he has to remove the rear intake to reach the other three coils." This highlights how common procedures on this V6 engine necessitate this complex job.

Symptoms

The need to replace or remove the intake manifold is rarely an issue by itself. Instead, it's a required step to fix other, more noticeable problems. Owners report symptoms that ultimately lead to this repair. A prominent symptom is a persistent engine misfire, often accompanied by a check engine light (like a P0306 code). This misfire can cause noticeable engine vibrations at idle and a distinct loss of power during acceleration.

Another key symptom is the presence of a vacuum or intake leak. This can manifest as a rough, unstable idle where the RPMs drop unexpectedly or surge. As one owner described a similar issue on an older model, "I had it so bad one time... the car would stall and had a hard time starting back up." While not directly from a 2020, this illustrates the drivability problems a significant air leak can cause. In more severe cases related to gasket failure, you might find coolant where it doesn't belong, which is a critical symptom. One owner diagnosing a misfire found, "Got a long Q-Tip and stuck it down there and sure enough.....green coolant smelling fluid."

Less directly, symptoms like the need to replace ignition coils or spark plugs on the rear bank of the V6 engine will also necessitate this procedure. Owners note that accessing these components is impossible without first removing the intake manifold assembly. This turns a simple parts swap into a major labor-intensive task.

Most Likely Cause

The primary cause necessitating intake manifold removal on the 2020 Nissan Maxima is the need to access components located beneath it, specifically the three rear ignition coils and spark plugs. The vehicle's transverse-mounted 3.5L V6 VQ engine has a very compact engine bay. The intake manifold is designed as a large, single-piece assembly that sits atop the engine valley, completely covering the rear cylinder bank.

Therefore, any repair involving the rear bank's ignition system—whether addressing a misfire caused by a bad coil, worn spark plugs, or even investigating coolant intrusion—requires the manifold to come off. This is not a design flaw but a packaging reality for a powerful V6 in a front-wheel-drive sedan. As confirmed in owner discussions, the labor quote for coil replacement explicitly includes this step. The manifold itself can also be a source of issues if its gaskets fail, creating vacuum leaks or, in conjunction with other failures, allowing coolant to seep into intake passages.

How to Diagnose

Diagnosing whether you need to tackle an intake manifold removal starts with identifying the root problem. You'll need a basic OBD2 scanner to read check engine codes. A code like P0300 (random misfire) or a specific cylinder code (e.g., P0301-P0306) points to an ignition or compression issue. If the misfire is on cylinder 4, 5, or 6 (the rear bank), you can be almost certain the intake manifold must be removed for access.

For suspected vacuum leaks, listen for a hissing sound around the manifold at idle. You can use a can of carburetor cleaner or propane (with extreme caution) to spray around the manifold gasket seams. If the engine RPM changes when you spray a specific area, you've found a leak. A smoke machine is the professional tool for this, generating visible smoke that will seep out at the leak point.

If you suspect coolant is leaking internally, perhaps from a failing intake manifold gasket (if it seals a coolant passage) or a more serious head gasket issue, inspection is key. As one owner demonstrated, "pulled the 6th cylinder spark plug this morning and could see coolant seeping into the engine just below the spark plug threads." Removing spark plugs (from the accessible front bank first to practice) and inspecting them for coolant residue or using a borescope to look into the cylinder can provide evidence. Remember, as an owner noted, "I'm not an expert mechanic. However, cooling systems are completely separate from the intake system that controls the air-fuel mixture for combustion." While separate, gasket failures can create intersections.

Step-by-Step Fix

Replacing or removing the intake manifold is an advanced DIY job. If you're not comfortable, skip to the cost section. Here’s a generalized guide based on the required access described by owners.

1. Safety First: Disconnect the negative battery terminal. Allow the engine to cool completely. Relieve any residual fuel pressure by loosening the gas cap.

2. Remove Engine Covers: Unclip and remove the plastic beauty cover(s) from the top of the engine to expose the intake manifold and throttle body.

3. Disconnect Intake Tract: Loosen the clamp on the intake rubber hose connected to the throttle body and remove the air intake assembly. Disconnect the Mass Air Flow (MAF) sensor electrical connector.

4. Disconnect All Attachments: This is the most meticulous step. You must disconnect everything attached to the manifold:

• Throttle body electrical connector and coolant hoses (clamp them).
• All electrical connectors for sensors on the manifold (like the MAP sensor).
• Vacuum hoses and the PCV valve hose. Label everything with tape.
• Fuel lines connected to the fuel rails (have rags ready for minor spillage).
• Any remaining brackets or wiring harnesses clipped to the manifold.

5. Remove the Intake Manifold: Unbolt the manifold from the cylinder heads. There will be numerous bolts of varying lengths. Keep track of their locations. Gently rock the manifold to break the seal of the gaskets and lift it straight off the engine. As one owner shared about a related component, "plastic valve covers and intake manifolds is where I draw the line," highlighting the care needed with these plastic components.

6. Address the Root Cause: With the manifold removed, you now have clear access to the three rear ignition coils and spark plugs. Replace them as needed. This is the core reason for the job in most cases. Inspect the manifold's gasket surfaces for cracks or warping and replace the intake manifold gaskets as a matter of course.

7. Reassembly: Installation is the reverse of removal. This is critical:

• Thoroughly clean the cylinder head and manifold mating surfaces.
• Install new intake manifold gaskets. Do not reuse old ones.
• Carefully guide the manifold into place, ensuring no hoses or wires are pinched.
• Hand-tighten all bolts before final torquing. Follow the manufacturer's specific torque sequence and specification (often found in a service manual) to avoid leaks or warping.
• Reconnect every hose and connector using your labels.

8. Final Steps: Reconnect the battery. Start the engine and let it idle, checking for leaks (fuel, coolant, vacuum). Use your OBD2 scanner to clear any stored codes and verify no new ones appear during a test drive.

Parts and Tools Needed

• Parts:
  • New Intake Manifold Gasket Set (OEM recommended for proper seal).
  • Replacement parts for the root cause: e.g., (3) Ignition Coils for rear bank (e.g., Hitachi or OEM), (6) Spark Plugs (NGK Laser Iridium recommended), or a new PCV valve.
  • A small amount of coolant for topping up after reconnecting hoses.
• Tools:
  • Basic socket set (metric, 8mm-14mm) with ratchets and extensions.
  • Torque wrench (essential for manifold bolts).
  • Torx or hex bits (for certain brackets or sensors).
  • Pliers and screwdrivers.
  • OBD2 scanner.
  • Shop towels, plastic bags, and labeling tape for organization.
  • Gasket scraper and surface cleaner.

Real Owner Costs

The cost is dominated by labor due to the time-intensive process. Owners discussing similar jobs provide clear data.

For a professional repair that requires intake manifold removal, such as replacing all six ignition coils, labor quotes are significant. One owner was "recently quoted $595 and $125 trip charge for just labor of swapping out the ignition coils." Another owner analyzed this, noting, "Seems like you're getting charged about $100/hour for the labor (6 hours) plus his driving time." This aligns with a 5-7 hour book time for this job at $100-$150 per hour.

Therefore, total professional costs can easily range from $800 to $1,200+ for labor alone, plus the cost of parts (coils, plugs, gaskets). If the manifold itself needs replacement due to damage, add several hundred dollars for the part.

The DIY cost is essentially just the price of parts—a gasket set ($50-$100), coils ($50-$150 each), and plugs ($10-$20 each). Your investment is time, patience, and the risk of error. For a skilled DIYer with the right tools, this can save over a thousand dollars.

Prevention

Preventing the need to remove the intake manifold revolves around proactive maintenance of the components it hides. Adhere strictly to the spark plug replacement interval (typically around 100,000 miles). Using high-quality fuel and ignition components can prolong coil life. Regularly inspect engine bay hoses, including the PCV valve hose, for brittleness or cracks that could lead to vacuum leaks. Addressing small issues like a rough idle early can prevent them from worsening. While you can't change the engine's design, maintaining the systems around it is the best way to avoid this invasive repair.

What Owners Say

Real experiences from NISSAN owners:

Success Stories

"I had it so bad one time in my CRX the car would stall and had a hard time starting back up. ended up changing all the clamps, radiator cap and bleed the system, problem solved." — maximanut2001 (source)

Owner Experiences

"I'm not an expert mechanic. However, cooling systems are completely separate from the intake system that controls the air-fuel mixture for combustion." — maximanut2001 (source)

"The AC stopped blowing cold air... feels like it's just blowing outside air. However, I noticed that when I press the recirculation button, there is no increase or decrease in blower noise as there always used to be." — RITE (source)

"I don't like super loud cars, but i like the back fire sounds. my cars loud enough after the cai and intake and throttle spacers. Just wanted to give it that extra performance sound without the whole ears bleeding kinda deal." — Jwillia481 (source)

Pro Tips from Owners

💡 "Got a long Q-Tip and stuck it down there and sure enough.....green coolant smelling fluid. This doesn't seem like an intake manifold issue and seems much more indicative of a head gasket." — mattyhuffer (source)

💡 "An update: pulled the 6th cylinder spark plug this morning and could see coolant seeping into the engine just below the spark plug threads. Got a long Q-Tip and stuck it down there and sure enough.....green coolant smelling fluid." — mattyhuffer (source)

Real Repair Costs

"I was recently quoted $595 and $125 trip charge for just labor of swapping out the ignition coils. Dude mentioned that he has to remove the rear intake to reach the other three coils." — vebong (source)

"Just wondering, is that a reasonable price just for labor? I've been noticing some engine vibrations at idle and some loss of power Seems like you're getting charged about $100/hour for the labor (6 hours) plus his driving time (2 hours) at $125." — The Wizard (source)

"Quote: Originally Posted by vebong I was recently quoted $595 and $125 trip charge for just labor of swapping out the ignition coils. Dude mentioned that he has to remove the rear intake to reach the other three coils." — The Wizard (source)

FAQ

Q: How long does it take to remove and replace the intake manifold? A: For a professional mechanic with all tools at hand, the book time is typically 5-7 hours. For a DIYer attempting it for the first time, it could easily take a full weekend (10-15 hours) to complete carefully and correctly, given the number of connections and the need for meticulous organization.

Q: Can I drive my car if I need this repair? A: It depends on the underlying symptom. If it's a minor vacuum leak causing a slightly rough idle, you might drive cautiously for a short time. If you have a confirmed misfire (especially with flashing check engine light) or coolant leaking into cylinders, driving can cause severe engine damage. It's best to avoid driving and address the issue immediately.

Q: Is removing the intake manifold a common issue on the Maxima? A: The manifold itself failing is not a widespread "issue." However, the need to remove it for routine maintenance and repairs is extremely common due to the engine layout. Any work on the rear spark plugs or coils makes this procedure a standard part of service for this vehicle, as echoed in multiple owner quotes about labor for coil replacement.

Q: DIY vs mechanic - what's recommended for this job? A: This is an advanced repair. It is recommended for experienced DIYers who are organized, patient, and have a full set of tools, including a torque wrench. If you have never performed major engine work, the risk of creating vacuum leaks, damaging plastic components, or misrouting hoses is high. For most owners, the consensus from cost discussions suggests paying a professional, while expensive, is the safer choice to ensure the job is done correctly.

Q: Is this repair only for fixing misfires? A: No, while accessing rear coils for a misfire is the most common reason, the procedure is also necessary for repairing certain vacuum leaks at the manifold gasket, replacing a faulty fuel injector on the rear bank, or diagnosing more serious internal issues like coolant leaks at the cylinder head.

Q: Will I need a special gasket sealant? A: Typically, no. The 2020 Maxima's intake manifold uses reusable rubber or multi-layer steel (MLS) gaskets that are installed dry. Using sealant on these gaskets can actually cause leaks or improper sealing. Always use the new gaskets designed for your specific engine and follow the factory service procedures.