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How to Fix Exhaust Leak at Flange? Detail Step by Step Guide

Are you wondering how to fix exhaust leak at flange? If the engine is louder than usual, it indicates exhaust leaks that need attention immediately.

Generally, people don’t understand the purpose of exhaust flanges in the engine unless they need to fix it. However, it is essential for the exhaust system, and it makes the exhaust system efficient. The primary purpose of flanges is to exhaust gasses out of the exhaust system without obstruction.

Moreover, flanges connect the exhaust manifold to the exhaust pipe. Usually, flanges are connected with a rubber gasket that seals the exhaust pipe with the manifold and avoids leaks. If the exhaust system has leaked, it causes a lot of noise. The exhaust flange repair is a complicated process and needs special attention.

In this article, I will guide you on how to fix the exhaust leak at the flange? Before starting with the topic, let us discuss the important parts of an exhaust system.

What is an Exhaust System?

Automobile exhaust systems caries away harmful gasses like carbon monoxide, nitrogen oxide, and hydrocarbon from the system. An effective exhaust system provides efficient fuel economy and is environmentally friendly. Let’s look at some essential components of an exhaust system.

1. Exhaust Manifold

The exhaust manifold collects all the exhaust gases from each cylinder into one point. Typically, it is of cast iron, and it connects engine exhaust ports.

2. Exhaust pipe

The major purpose of the exhaust pipe is to allow gasses to escape from the system without obstruction. Obstruction in exhaust pipes causes a problem in car effectiveness.

3. Exhaust Flanges

Exhaust flanges are the small part of the exhaust system that connects the exhaust pipe to the manifold. Moreover, if there is a leak in the flanges car exhaust system and car performance is compromised. Flanges leaks are hazardous and highly toxic and can cause damage to the vehicle’s performance.

4. Muffler

When emissions pass through the exhaust system muffler reduces the sound of the car engine. Additionally, for leaks in the muffler, muffler sealer minimizes the sound of the engine.

5. Hangers

Hangers are known as exhaust support. They secure and support exhaust pipes that are present underneath the car.

6. Catalytic Converter

The catalytic converter filters the toxic byproduct that comes exhaust system. For your toyota car, you can choose AUTOSAVER88 Catalytic Converter.

How to Identify exhaust leak at flange?

Before repairing, let us discuss how to identify exhaust leaks in the exhaust system. Moreover, the best way to inspect exhaust leaks is by physically monitoring the exhaust manifold, exhaust pipe, and flanges.

These are the sign of exhaust leaks.

  1. Loud engine noise
  2. Decreased fuel economy
  3. vibrating gas pedal
  4. Gas smell
  5. white exhaust smoke
  6. Reduced acceleration and power of an automobile
  7. Engine overheating

How to fix exhaust leak at flange?

When you start the engine and notice a loud sound coming out the exhaust, it is the main proof of exhaust leaks. If you hear hissing or tapping noise, it indicates exhaust manifold leaks. Moreover, if you hear a rumbling sound that is much louder than usual, it suggests an exhaust flange leak. Let us look at the exhaust repair flange process.

 Step 1: Turn off the engine

After identifying the problem, turn off the engine and let it cool for several hours. It is because the exhaust pipe is too hot.

 Step 2: Clean the location of the leak

Before cleaning, use rubber gloves and glasses to avoid dirt in your eyes and hands. Use sandpaper to remove material from the surface of the leak. Moreover, after scrubbing the surface apply acetone to clean the damaged area.

 Step 3: Use exhaust seal

Usually, the hole in the exhaust pipe is small, and by using exhaust tape, it is easily fixed. Moreover, if there is a gap between the flanges use adhesive sealant to cover the gap. It is not a permanent solution. However, it works well.

 Replacement exhaust flange

Generally, all automobile has flange connector that connects exhaust parts like mufflers, exhaust manifold, the catalytic converter. The exhaust manifold gasket seals the gap between the exhaust port and exhaust manifold. It not only reduces the sound of the engine but also stops escaping harmful gases. Most exhaust manifold gaskets don’t need a sealant. However, some gasket comes with their sealant. Exhaust manifold gasket sealant can burn due to extreme heat in the header interference.

Let’s look at the replacement process of the exhaust flange.

Step 1: Inspect the pipe with a leak

The exhaust manifold flange gasket connects the front pipe. However, the rear pipe connects with the exhaust pipe. To access the leak, disconnect the rear flange connection.

 Step 2: Identify and remove the bolts and screws

The bolts and screws secure the flange from damage. Moreover, when the car is jacked up, bolts and screws are easily identified. Take a ratchet to unscrew or loosen the screw. Remove all the bolts, except bolts that are on the sides of the header.

 Step 3: Separate the flange connection

Hangers provide support to the exhaust pipe. Use a hanger tool to release hangers that are near the flange. Additionally, disconnect every connection on the exhaust pipe and manifold that are near the flange.

 Step 4: Clean the flange connector

Use a clean cloth to clean the surface. If the exhaust pipe is rusty use sandpaper to scrub the rust away.

 Step 5: Remove the old flange

Sometimes old flange gets stuck; use a knife or flat metal piece to remove the flange. Furthermore, scrape the dirt off for proper seal. Apply automobile sealant on both sides of the gasket for good grip.

 Step 6: Connect the new flange gasket

Properly fit the new flange to avoid any leaks. Now reconnect the flange connector, hangers, screws, and bolts. Start the automobile and check for any leaks. Suppose you notice any sound, re-tighten the hardware again. Sometimes flange gasket requires welding. Weld-on exhaust flange requires mechanic assistance because it is not an easy task.

FAQ (Frequently Asked Questions)

1. How much does it cost to fix an exhaust flange leak?

Generally, exhaust flange repair requires 2-3 hours. Some automobile repair shops charge between $80 to $100 per hour. So approximately the cost of exhaust repair is $160 to $ 300.

2. Can you use JB Weld on the exhaust flange?

No, J-B Weld is not for repairs in extreme temperatures, and the combustion chamber is extremely hot. Most experts don’t recommend J-B weld for exhaust manifold, exhaust pipe, and catalytic converter repairs.

3. Can you drive with an exhaust manifold leak?

Yes, driving with an exhaust leak is not safe because fumes in the exhaust chamber contain toxic gases like carbon monoxide. Exhaust leaks shouldn’t be ignored because it a safety hazard.

4. Will an exhaust leak throw a code?

Commonly, it is rare for an exhaust leak to throw a code. However, it depends upon the location of the exhaust and O2 sensor.

5. What does an exhaust leak sound like?

 An exhaust leak sounds like ticking or puffing. However, the rumbling sound louder than usual is the indicator of an exhaust leak.


The exhaust system is one of the most essential systems. It exhausts toxic gas away from the car and improves the fuel economy. This article answers the question how to fix exhaust leak at flange? Although flanges don’t seem to be an important part of an exhaust system. However, it’s essential for the health of the exhaust system.

If the exhaust system is not working well, car consumes more fuel, makes noises, and the engine is not efficient. Regular checks for leaks can help in avoiding this problem.

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Shafiqule Islam is a graduated Mechanical Engineer. He has both on hand and managerial job experience of 15 years in automobile maintenance field. He served as Captain in Electrical and Mechanical Engineering Corp of Army, Technical Head in Taxi Cab business, Head of Plant in Car assembly plant. He is writing automotive contents to share his expertise knowledge to car lovers for solving their vehicle issues.

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