How to Install an Engine in a Car

by Eli Laurens
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Car engines are designed to be replaced relatively simply when they wear out. The motor of any automobile can be removed and replaced with a new one by most competent mechanics. The average backyard mechanic should spend about 20 hours replacing the typical engine.

Installing a replacement engine into a car

Step 1

Prepare the old engine for removal. Disconnect and remove the battery, fan belts, and air intake housing from the motor. Disconnect and remove all vacuum hoses, fuel lines, and throttle cables. Drain all fluids from the engine, including oil, coolant, gasoline and Freon. Unbolt the exhaust manifold pipe from the tailpipe, using a cutting torch where necessary. Remove all coolant hoses and the radiator. Placing a floor jack on the bottom of the motor, relieve pressure from the motor mounts and loosen, but do not remove them.

Step 2

Uncouple the motor from the transmission. On rear wheel drive vehicles, this will be at the rear of the engine. On front wheel drive models, this will be on the right underside of the motor between it and the drive wheel. Most transmissions will unbolt easily but will not disconnect from the engine until the engine is removed.

Step 3

Secure the engine hoist chain around the bottom of the engine, unbolt the motor mounts completely, and then lift the motor out. The hoist chain should be placed around the exhaust manifolds, strapped around the block and tightened. As the engine comes free, it will disconnect from the transmission and the weight will shift. Lift the motor straight up and out of the engine bay. Don't lean it on the car, as it is not designed for this amount of weight. Place the motor in a safe spot, and do not leave it hanging from the hoist for extended periods.

Step 4

Install the new engine. Using the hoist, slowly lower the new motor into position. The first connection should be the transmission, making sure that the drive shaft matches up with the transmission's input shaft. Secure the bolts to the transmission, then install the motor mounts. New mounts should be used--never reuse old motor mounts. With the motor in place, begin attaching the exhaust manifold and cooling system. The radiator and hoses should be connected before the belts and accessories.

Step 5

Reinstall the vacuum and fuel lines, and the throttle cables and accessories. Be sure to secure them well, as vacuum and fuel pressure are critical. The engine computer, if available, can be reused from the old motor if they are the same type and model of engine, with the same kind of intake (fuel injection). Most manufacturers will not supply a new computer with inexpensive aftermarket engines.

Step 6

Reinstall the air intake manifold, battery, and fan belts. New "crate" engines, or fully assembled mail-order engines, come with all of the necessary intake parts already installed. Some manufacturers will skimp on this, and not include simple things like screws or intake gaskets. It is possible to reuse parts from the old engine, but they should be cleaned and inspected carefully beforehand.

Step 7

Refill all of the fluids, and any "break-in" fluids recommended by the manufacturer.

Step 8

Doublecheck any connection points, and do not crank the engine until everything has been inspected completely. There will not be any fuel in the line until the pump is worked for a few minutes. When cranking a new motor for the first time, don't rev the engine over 2000 rpm's for at least it's first hour, and to change the oil once after the first 500 miles.

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