Wednesday, October 30, 2013

How to Fix the Exhaust Manifold

When an engines spark plug ignites the air/fuel mixture within the cylinder, the mixture explodes and pushes the piston downward. Once the engine reaches its lowest point within the cylinder, the exhaust valve in the cylinder head opens. As the piston then travels upwards, it pushes the gases which remain from the explosion through the open exhaust valve and ultimately out of the engine. These noxious gases are commonly referred to as "exhaust," and can prove to be deadly if you are exposed to the gases for a long period of time. For this reason, the exhaust gases are routed through exhaust manifolds, which in turn carry the gases to the exhaust pipes. Between the exhaust manifold and the engine is a gasket designed to prevent the gases from escaping before they reach the exhaust manifold and entering the interior of the vehicle. If this gasket becomes damaged, it needs to be replaced.

Instructions

    1

    Ensure that the exhaust manifold is cool by allowing the engine to sit without running for at least two hours. Exhaust manifolds can get extremely hot as the exhaust gases flow through them, and can therefore pose a serious burn hazard.

    2

    Remove the bolts that hold the manifold to the cylinder head with a wrench. Exhaust manifold designs differ, but most exhaust manifolds have one bolt on both sides of each pipe.

    3

    Pull the exhaust manifold away from the cylinder head just enough to expose the manifolds gasket. A stubborn manifold can be freed from the cylinder head by tapping the manifold with a rubber mallet, sometimes referred to as a "dead blow" hammer. The mallets rubber composition prevents the hammer from denting the manifold. Note that the manifold need not be removed from the engine compartment, which would require the manifold to be disconnected from the exhaust pipe. The manifold must only be pulled away from the cylinder head to access the manifolds gasket.

    4

    Remove the old exhaust manifold gasket. The gasket will either stick to the cylinder head or to the manifold itself. The gasket can usually be peeled away, but a stubborn or burnt gasket may have to be scraped away with either a flathead screwdriver or a gasket scraper.

    5

    Place a new exhaust manifold gasket against the manifold, then press the manifold against the cylinder head. Hold the manifold against the cylinder head with one hand, then insert the manifolds retaining bolts through the manifold and into the cylinder head with the other hand. Do not apply gasket sealer onto this gasket.

    6

    Tighten each of the manifolds retaining bolts in small increments with a wrench until each bolt is tight to complete the repair. Tightening the bolts in small increments is necessary to ensure that the gasket seats properly and does not warp.


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