Step 3: Remove engine components in the way of the exhaust manifold. Each vehicle will have different parts that are in the way of the exhaust manifold that will need to be removed before you attempt to remove the exhaust heat shield. Refer to your vehicle service manual for exact steps on how to remove these components.
The heat shield will vary in size, shape and materials it is constructed, but typically covers the exhaust manifold on most domestic and import vehicles sold in the US after Step 4: Remove heat shield.
On all cars, trucks and SUV's made after , US automotive laws required that a heat shield be installed over the exhaust manifold to reduce the potential of vehicle fires caused by burning fuel lines, or other materials that come into contact with the excessive heat produced by the exhaust manifold.
To remove the heat shield in most cases, you'll need to unscrew two to four bolts that are on top or to the side of the exhaust manifold.
Step 5: Spray the exhaust manifold bolts or nuts with penetrating fluid. Due to the excessive heat produced by the exhaust manifold, it's quite possible that the bolts holding this component to the cylinder head will become fused together or rusted. To avoid breaking the studs, apply a liberal amount of penetrating oil on each nut or bolt that holds the exhaust manifold on the cylinder heads. Once this step has been completed, you might want to complete his step below the vehicle where the exhaust manifold connects to the exhaust pipes.
Usually there are three bolts connecting the exhaust manifold to the exhaust pipes. Spray penetrating fluid on both sides of the bolts and nuts and let it soak in while you remove the top portion. Remove the exhaust manifold using a socket, extension and ratchet. If you have access to impact or air tools, and have room in the engine compartment, you can use these tools to remove the bolts.
Step 6: Remove the exhaust manifold from cylinder head. After the bolts have soaked for about 5 minutes, remove the bolts that secure the exhaust manifold to the cylinder head. Depending on the vehicle you are working on, there will be one exhaust manifold or two; especially if it's a V-style engine.
Remove the bolts in any order however when you install the new manifold, you'll need to tighten in a specific order. Step 7: Remove exhaust manifold from exhaust pipe: Once you've removed the bolts holding the exhaust manifold to the cylinder head, crawl underneath the vehicle to remove the bolts and nuts securing the exhaust manifold to the exhaust system.
Most of the time there is a bolt on one side and a corresponding sized nut on the other. Use a boxed end wrench to hold onto the bolt and a socket to remove the nut or vice-versa depending on your ability to access this part. Step 8: Remove old exhaust manifold gasket. On most vehicles, the exhaust manifold gasket will be metal and easily come off the cylinder head studs once you've removed the exhaust manifold from the vehicle.
Remove the old exhaust manifold gasket and throw away. Step 9: Clean the exhaust ports on the cylinder head. It's important to remove excess carbon build-up on the exhaust ports or inside the exhaust port before you install a new exhaust manifold. Using a can of carb cleaner, spray onto a clean shop rag and then wipe the insides of the exhaust ports until the port appears to be clean.
Also, using some steel wool or very light weight sandpaper grit, lightly scrub the outsides of the ports to remove any pits or residue on the outside of the exhaust port. On most vehicles you'll have to install the bolts holding the exhaust manifold onto the cylinder heads in a certain pattern. Please refer to the service manual of your vehicle for exact instructions and recommended torque pressure settings for reinstalling a new exhaust manifold.
The steps for installing the new exhaust manifold are in reverse of the removal steps as indicated below:. Step 1: Attach the new exhaust manifold gasket onto the studs on the cylinder head. Step 2: Install a new gasket between the bottom of the exhaust manifold and the exhaust pipes.
Step 5: Hand-tighten each nut onto the cylinder head studs. Tighten nuts in the precise order as instructed by the vehicle manufacturer until each nut is hand-tight and the exhaust manifold is flush against the cylinder head equally. Step 6: Tighten exhaust manifold nuts. Tighten to the require torque pressure and in the exact pattern as recommended by the vehicle manufacturer.
Step 8: Reattach parts. Reattach engine covers, coolant lines, air filters and other parts that were removed to gain access to the exhaust manifold. Step 9: Refill radiator with recommended coolant. Refill the coolant if you had to remove coolant lines. Since most problems with the exhaust manifold are easy to identify by sound or smell, once you test fire the vehicle; the repair should be obvious.
After you've cleared the error codes from the computer, test-start your vehicle with the engine hood up so you can complete the following checks:. LOOK: for any leaks or gases escaping from either the exhaust manifolds connection to the cylinder head or the exhaust pipes below. As an added test, it is a good idea to road test the vehicle with the radio off to listen for any road noise or excessive noise coming from the engine compartment.
This article originally appeared on YourMechanic. Autoblog is partnering with YourMechanic to bring many of the repair and maintenance services you need right to you. Get service at your home or office 7 days a week with fair and transparent pricing. We get it. Ads can be annoying. But ads are also how we keep the garage doors open and the lights on here at Autoblog - and keep our stories free for you and for everyone. As the first component in the exhaust system , the exhaust manifold collects the exhaust fumes released from the engine cylinders and directs them to the catalytic converter.
In turbocharged engines, the turbocharger is situated downstream of the exhaust manifold. The design of the exhaust manifold has a significant influence on the performance and torque characteristics of an engine, as does the design of the connected pipes. The fact that the individual exhaust tracts are merged into one ensures that pulsations, i.
Exhaust manifolds are often made of alloyed cast iron, which is able to withstand the high exhaust temperatures. Alternatively, exhaust manifolds made of stainless steel are also used. Exhaust manifolds are subject to high thermal stress because they are the first component to convey exhaust fumes away from the engine.
The significant expansions caused by temperature combine with the associated cyclical tension resulting from repeated heating and cooling to subject the material to fatigue. In turn, this can eventually cause the component to fail. A faulty manifold must be taken off and inspected, and replaced with new manifold. So can labor, as the exhaust manifold is connected to the engine, which could make it quite difficult to access.
Unfortunately, the exhaust manifold is an absolutely critical component to your vehicle, and if you ignore your cracked manifold, the problem will only get worse and more expensive. Openbay, an award-winning online e-commerce marketplace for automotive repair and services and a provider of SaaS-based solutions for the automotive care industry, is transforming the experience for automotive repair and service for consumers and the way that automotive care businesses acquire and service customers.
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