Removing the intake manifold on a Nissan Almera G15: detailed instructions with photos and tips

Intake manifold Nissan Almera G15 - a key component of the engine power system, responsible for the uniform distribution of the air-fuel mixture among the cylinders. Its dismantling may be necessary when cleaning the throttle valve, replacing gaskets, or repairing the exhaust gas recirculation system (EGR) or diagnosing air leaks. However, the procedure requires caution: errors during removal can result in damage to sensors, hoses, or the manifold itself.

This article will help you figure out how to properly remove the intake manifold on Almera G15 with engines HR16DE or K4M, avoiding typical problems. We will describe each step in detail - from tool preparation to reassembly - and also point out critical points that even experienced craftsmen often miss (for example, a mandatory check of the condition of the bolts securing the manifold to the cylinder head after 100+ thousand kilometers). If this is your first time taking on this work, we recommend reading the article to the end before starting disassembly.

Preparing for work: tools and conditions

Before you begin dismantling, make sure you have everything you need. You will have to work in a cramped engine compartment, so you cannot do without specialized tools. Here is the minimum set:

• 🔧 A set of sockets and ratchet wrenches (necessarily with an extension and a cardan for hard-to-reach bolts).
• 🔨 10, 12 and 14 mm socket wrenches (for attaching the manifold and throttle assembly).
• 🔩 Screwdrivers with flat and cross-shaped tips (for clamps and sensor connectors).
• 🧰 Pliers with narrow jaws (for removing spring hose clamps).
• 🛠️ Sealant for gaskets (for example, Loctite 574 or equivalent).
• 🧴 Carburetor or throttle cleaner (for flushing manifold channels).
• 📸 Phone or camera (to record the location of hoses and connectors).

Also prepare your workplace: the engine must be cold (working on a hot engine can cause burns and deformation of plastic elements). It is advisable to carry out disassembly in a garage with good lighting or outside in calm weather - dust and debris should not get into the intake ducts. Don't forget to disable negative battery terminalto avoid short circuits when working with sensors.

⚠️ Attention: If your Almera G15 equipped with a system EGR, before removing the manifold, be sure to clean the recirculation valve from carbon deposits. Otherwise, soot particles may enter the cylinders during dismantling, which will lead to accelerated wear of the piston group.

Removing air ducts and throttle assembly

The first stage is to free access to the collector. Start by removing the duct connecting the air filter to the throttle body:

1. Loosen the clamps securing the corrugation to throttle assembly And air filter housing (use pliers or a screwdriver).
2. Disconnect the mass air flow sensor connector (Mass air flow sensor) - it is located on the pipe between the filter and the corrugation.
3. Remove the corrugation by pulling it up. Be careful: on older machines, the plastic can become brittle.

Next, proceed to the throttle assembly. It is important here not to damage the gasket between the assembly and the manifold. Proceed like this:

• 🔧 Unscrew the 4 throttle mounting bolts (usually a 10 mm socket).
• 🔌 Disconnect the throttle position sensor connector (TPDZ).
• 💧 Carefully remove the assembly without distorting it - the gasket may stick to the manifold.

If the throttle valve is very dirty, it makes sense to clean it before removing the manifoldusing carburetor cleaner. This will simplify further assembly. Do not use metal brushes - they scratch the surface of the damper, which subsequently leads to air leaks.

Loosen the air duct clamps|Disconnect the mass air flow sensor connector|Remove the corrugation|Unscrew the throttle assembly|Disconnect the mass air flow sensor connector|Check the integrity of the throttle gasket-->

Disconnecting hoses and electrical connectors

At this stage, most errors are associated with damaged hoses or mixed-up connectors during reassembly. To avoid problems, act systematically:

First disconnect everything vacuum hoses, leading to the collector. There are usually three of them:

- Hose from valve EGR (if the system is installed).

- Hose from the brake booster.

- Hose from the crankcase ventilation system (PCV).

For convenience, mark the hoses with tape or take a photo of their location. Vacuum tubes often dry out and break during dismantling - if cracks are noticeable, replace them in advance.

Next, disconnect the electrical connectors:

- Absolute pressure sensor (MAP sensor), located on the manifold.

- Valve connector EGR (if present).

- Idle air control connector (RXX), if it is integrated into the throttle assembly.

⚠️ Attention: On Almera G15 with engine HR16DE connector MAP sensor often sticks due to oxidation. Do not pull the wires - gently press the latch and swing the connector left and right.

element	Location	Features of dismantling
EGR Vacuum Hose	On top of the manifold, next to the valve	It may stick - remove carefully, without jerking
Brake booster hose	Below the manifold, closer to the windshield	Check for cracks - if they break, the brakes will become “oaky”
MAP sensor connector	At the end of the manifold, under the throttle	The latch is fragile - do not break when disconnecting
Fuel pipes (if you remove the manifold with a ramp)	Behind the manifold, under the receiver	Before disconnecting, release the pressure in the system!

Removing the intake manifold: step-by-step instructions

When all interfering elements have been removed, you can begin to remove the collector itself. On Nissan Almera G15 it is attached to the cylinder head (cylinder head) 6–8 bolts (depending on the year of manufacture). Here's how to proceed:

1. Unscrew the bolts securing the manifold to the cylinder head, starting from the edges and moving towards the center. This will help avoid flange deformation. Use a ratchet wrench with an extension - access to the bottom bolts is limited.
2. Carefully lift the manifold up. If it does not give in, do not pull by force - check that all hoses and connectors are disconnected. People often forget about the system tube PCV, hidden under the throttle.
3. Remove the manifold and inspect the gasket. If it is torn, hardened or has burnt marks, replace it necessarily - even minor defects will lead to air leaks.

On engines HR16DE the collector often “sticks” to the cylinder head due to corrosion. In this case, do not hit it with a hammer - use a wooden block as a lever, resting on a reliable point. If the collector is tight, check to see if there is a piece of bolt left in the cylinder head channels (this happens during previous repairs).

After removing the manifold, close the cylinder head inlet ports with a clean rag or special plugs. The entry of debris or moisture into the cylinders is fraught with serious consequences, including scoring on the walls.

What to do if the manifold mounting bolt breaks?

If the bolt breaks off when unscrewing, do not try to drill it yourself - the risk of damaging the threads in the cylinder head is too great. Best option:

1. Remove the manifold, leaving the piece in the hole.

2. Have a turner make a special extractor, or use a broken bolt removal kit (such as Irwin Bolt-Grip).

3. After removing the fragment, check the thread with a tap and, if necessary, restore it.

Cleaning and diagnostics of the collector

When the collector is removed, you have an excellent opportunity to assess its condition and carry out preventive cleaning. Please note the following points:

• 🔍 Carbon deposits in channels — its accumulation narrows the flow area, impairing the filling of the cylinders. Particularly critical for engines HR16DE, where the reservoir has complex geometry.
• 💨 Traces of oil - indicate a malfunction of the crankcase ventilation system (PCV) or wear of the piston rings.
• 🔥 Burnt gaskets - a common problem after 150 thousand km. The gasket between the manifold and the cylinder head must be elastic and free of cracks.
• 📉 Flange deformation — if the collector is damaged by overheating, it will have to be ground or replaced.

For cleaning use special means (For example, Liqui Moly Pro-Line Drosselklappen-Reiniger or Wynn's Air Intake System Cleaner). Do not use aggressive solvents - they can damage plastic and rubber parts. Cleaning algorithm:

1. Soak the collector in warm water with detergent for 30–60 minutes (to soften the carbon deposits).
2. Clean the channels with a soft-bristled brush, avoiding scratches.
3. Wash the collector with a high-pressure water jet, then dry with compressed air.
4. Check the tightness of the gaskets and replace them if necessary.

Pay special attention EGR valve (if it is integrated into the manifold). Its channels are often clogged with soot, which leads to unstable engine operation. To clean, use a wire brush and cleaner. Wynn's EGR Cleaner.

- Correct connection of vacuum hoses.

- Integrity of the gasket between the manifold and the cylinder head.

- Throttle valve adjustment (may require adaptation via diagnostic scanner).-->

Reassembly: nuances and typical mistakes

Installing the manifold in place seems simple, but this is where most of the pitfalls lie. Main rule: all gaskets and seals must be new. Even if the old gasket looks intact, over time it loses its elasticity and begins to leak air.

Assembly order:

1. Install a new gasket between the manifold and the cylinder head. Do not use sealant if the gasket is paper or rubber - it is only needed for metal gaskets.
2. Carefully lower the manifold into place, lining up the bolt holes. Do not twist it - this may dislodge the gasket.
3. Tighten the bolts in a crisscross pattern in 2-3 increments, starting from the center. Tightening torque for Almera G15 — 20–25 Nm (do not exceed, otherwise you will break the thread!).
4. Reconnect all hoses and connectors in reverse order. Check if the vacuum tubes are mixed up.

After assembly, start the engine and let it idle for 5-10 minutes. Please note:

- RPM stability (must be within 750–850 rpm).

- Absence of extraneous noise (whistle indicates air leaks).

- Instrument readings (for example, sensor MAP should produce adequate pressure values).

⚠️ Attention: If it lights up after assembly Check Engine, don't panic. First check:

- The tightness of the sensor connectors.

- Integrity of vacuum hoses.

- Correct connection of the throttle assembly.

Reset the error with a diagnostic scanner or by disconnecting the battery terminal for 10 minutes.

Frequent problems after removing the manifold and their solutions

Even with careful work, problems may occur after dismantling the collector. Here are the most common of them and how to eliminate them:

Problem	Probable Cause	Solution
Floating idle speed	Air leak through gasket or leaking hose	Check the tightness of the system with a smoke generator or soap solution
Engine troubles	Debris entering the cylinders or damage to the cylinder head gasket	Remove the spark plugs and check the compression. Repeat disassembly if necessary
Increased fuel consumption	Incorrect operation of the MAP sensor or mass air flow sensor after disconnection	Check the sensor readings with a scanner, clean the contacts
Whistle when revving up	Crack in manifold or gasket	Replace the gasket and, if necessary, the manifold

If problems persist, refer to the log files ECU (electronic control unit). Type error codes P0171 (lean mixture) or P0300 (misfire) will indicate a specific malfunction. For Almera G15 any diagnostic scanner with protocol support will do OBD-II, for example, ELM327 or Launch CReader.

In most cases, problems after removing the manifold are related to human factor — you forgot to connect the hose, did not tighten the bolts enough or damaged the gasket. Follow each step carefully and problems will be avoided.

FAQ: Answers to frequently asked questions

Is it possible to remove the intake manifold on an Almera G15 without removing the throttle body?

Technically it is possible, but it will significantly complicate the task. The throttle assembly interferes with access to the manifold mounting bolts, especially the lower ones. In addition, there is a high risk of damaging the gasket between the assembly and the manifold during dismantling. We recommend removing the throttle in advance - it will take no more than 10 minutes, but will save time and nerves.

What sealant should I use for the manifold gasket?

For Almera G15 A high-temperature silicone-based sealant is suitable, for example:

- Loctite 574 (withstands up to +300°C).

- Permatex Ultra Black (resistant to oil and antifreeze).

- ABRO 11-AB (budget option).

Apply sealant thin layer only on metal gaskets. No sealant is required for paper or rubber seals.

How long does it take to remove the manifold?

Time depends on experience and condition of fasteners:

- Newbie: 3–5 hours (including cleaning and diagnostics).

- For an experienced master: 1.5–2 hours.

The main delays are usually caused by stuck bolts or brittle plastic hose clamps. If the bolts do not come off, do not rush - use penetrating lubricant (WD-40 or Liqui Moly MoS2-Spray) and give it time to work.

What happens if you don't replace the manifold gasket?

Ignoring gasket replacement will lead to:

- Air leak → unstable speed, errors P0171/P0174 (lean mixture).

- Vacuum leak → drop in power, problems with the brake booster.

- Oil ingress into the intake tract (if the gasket between the manifold and the cylinder head is damaged) → carbon deposits on the valves, smoking.

The cost of a new gasket (about 300–800 rubles) is not comparable to the risks. Always install a new seal kit.

Is it possible to clean the manifold without removing it from the car?

Partially yes, but the efficiency will be low. Without dismantling, you can only clean visible surfaces (such as the throttle body or inlet pipes). Manifold channels, valve EGR and the areas around the sensors will remain inaccessible. For complete cleaning (especially if heavily soiled), removal is necessary.