Rebuilt Engine?

Here are some tips on how to break it in right.

By Bill Siuru



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You have a perfectly serviceable truck or other piece of equipment except for one major problem: The engine is worn out.
Rather than buy new, you might decide to recycle the engine. You can either rebuild an engine yourself or buy a remanufactured one from a factory. In either case, the break-in period for your "new" engine will be crucial to its life expectancy, according to the Automotive Engine Rebuilders Association.

Here are some tips from the AERA for breaking in a newly installed engine:

Check the engine manufacturer's recommendations or owner's manual for the proper type of oil to use during the break-in period. Most suggest using heavy-duty detergent oils, which contain an extreme pressure additive. Special break-in oils should not be used unless specified by the manufacturer.

Do not use synthetic oils for the first 5,000 miles. They are too good at reducing friction. Certain predictable amounts of friction are required for proper break-in of pistons and rings.

Use new coolant that is compatible with aluminum engine components and blended to a mixture of no more than 60% antifreeze and 40% water. A good sealer with rust inhibitors should be added to the cooling system to prevent rust and scale deposits and to guard against coolant seepage.

Before starting the engine for the first time, recheck to make sure it has been properly prelubricated. Start the engine, run at fast idle (approximately 1,500 RPM)and check the oil pressure. Run the engine for 30 minutes even though coolant may rise to operating temperature in a few minutes. If necessary, readjust tappets, carburetor and ignition timing. If the coolant boils over, stop the engine and allow it to cool. Then start again and proceed as above. If overheating occurs here, it's probably because friction is still too high; but check for other problems.

Check for air leakage from manifolds. This can cause a lean air-fuel ratio, which leads to harmful detonation.

Make a test run at 30 mph. Periodically accelerate to 50 mph, and decelerate rapidly. Repeat this procedure at least 10 times. Apply loads to the engine for short periods to increase ring pressure against the cylinder walls. This helps seat the rings. The rapid deceleration increases vacuum and gives extra lubrication to the pistons and rings.

Drive normally but not at continuous high speeds or under heavy loads for the first 500 miles. Change oil and filters after 500 miles. Operate trucks with only light loads.
For more information, contact AERA at 1-888-326-2372 or 847-541-6550. Or visit the Web site at http://www.aera.org.