How To Replace a Car Engine

First of all, a word of caution here: changing your engine is not an easy task. It requires a deft knowledge of your car and mechanics. It is not typically one of the things that regular car owners can do, and if you’re not that confident about your ability to repair your automobile, you may be doing yourself (and your car) a favor if you hire a professional to do it. The engine is the heart of your machine and it is connected to just about every moving piece of your car, so much care has to be exercised when working around it. It is certainly not for the faint of heart.

If the previous paragraph has convinced you that you’re not cut out for this task, you can start canvassing prospective car auto repair shops that could help you with your problem.

If you’re still reading then you’re probably confident with how well you know your car and your skills as someone who can replace an engine.

Make sure that the engine is the problem. An engine would usually exhibit major issues after 150,000 miles on the tachometer. Through a car's servicable life, you would often only need to replace lubricants, spark plugs, high tension wires, and hoses. It's therefore safe to check for other problems first. If you can troubleshoot the problem and deduce that the trouble is coming from parts other than the engine--the starter or the transmission, for instance--you just have to replace those parts and not the entire engine itself. You might also need to check if it’s just parts of the engine that need replacement or rebuilding, such as the valves, crankshaft, and the like. If you’re sure that it’s the engine, then you’re really in for a long day.

Have a replacement engine ready. The most obvious supply that you need for this project is a brand new engine. These may be quite expensive and most people would rather buy another car than replace an engine. If you’re determined to not give up on your car, head to your local dealership or auto shop and purchase an engine that is compatible with your car. You might also be able to get spare or “surplus” engines from used cars. You would also need special tools such as a engine hoist and stand. It might not make sense to purchase these tools, so you can rent or borrow instead from your neighborhood auto repair shop.

Once you're ready with your tools and replacement engine, here are step-by-step instructions on changing your car's engine.

  1. If you can remove the car's hood, then it would give you easier access to the engine block. Otherwise, open the hood fully and hold it in place at a vertical position.
  2. Disconnect the battery. Start with the negative terminal (black or green), then with the positive terminal (red). Then proceed to removing parts and connectors at the top of the engine. This includes the high tension wires and distributor cap. Depending on your engine, you would also need to remove the air intake and filter.
  3. Cut off the fuel supply by unplugging the fuel lines. Be sure to store any residual fuel in a fuel-approved container (a big airtight jar will do). Disconnect the throttle cable. Make sure that all the removed parts are accounted for.
  4. Then you will need to disconnect all hoses. This includes the radiator inflow and outflow hoses.
  5. Next, you need to take out the compressor from the air conditioning system.
  6. You also need to remove the alternator. This is bolted onto the engine block with a main bolt and a tightness adjusting bolt. Be sure to disconnect the alternator wire from the battery, too. Do the same for the power steering pump if your car has one.
  7. Jack up the car's front, and remove the front tires. Be sure that the handbrake is engaged, so the rear tires won't roll. Chock the car's rear to be sure.
  8. Remove the  the radiator, exhaust shield and pipe.
  9. Once you remove the motor mount, the engine should be visible. First drain any excess liquid that may have been retained, such as lubricant and coolant. Support the engine using the hoist. You would then need to remove any remaining bolts that attach the engine to the supports. Be sure to remove the starter, too. When the engine has been disengaged from the engine support, you can now use the hoist to lift it up.

Install the new engine. Once the old engine has been removed, you can now install the new engine, reconnect all the mechanical parts that you removed in reverse order. Be sure to fill the new engine with lubricant before initial testing. Check for leakages and broken connections before going for a test run.

Once you’re sure you’ve replaced all the nuts, bolts, hoses, and other connections, take your car out for a short test drive, to see if the engine runs well. You might have to do some calibrations and tune ups later on, to make sure everything is in order.


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