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13Apr Engine Rebuild and Overhauled- NOLA Automotive Repairs

Engine Overhaul or Rebuild: What’s the difference?

By NOLA AutomotiveRepairs | 0 Comments

There are obvious signs that will tell you that it’s time to have your vehicle’s engine overhauled. Likewise, there are ways to know if the best way to deal with the issues with your vehicle’s engine is a rebuild.

Knowing when you need an overhaul or a rebuild is crucial so you get the best service for your engine without causing further damage and incurring unexpected costs.

Moreover, you should be able to work with an experienced team of technicians to help you determine whether your engine needs an overhaul or a rebuild.

What is an Engine Rebuild?

Engine rebuilds are most often suggested by the experts when an engine has experienced normal wear and tear because of use. Technicians and mechanics work together to put back together all the parts of an engine into like-new condition.

All parts are examined and replaced if they aren’t within new tolerances.

Engine Rebuild- NOLA Automotive Repairs

The processes involved would usually include:

  • Over-boring the cylinders
  • Machining a crankshaft
  • Replacing the rod
  • Replacing the crankshaft bearings

The main purpose of an engine rebuild is to create an engine that is as close to new condition as is possible to obtain from the existing engine. Experts make sure that all tolerances between the various parts should be within factory specifications for a new engine.

Some car owners would say that a rebuild is basically all new parts. This is necessary when internal components of an engine fail to function properly and the car becomes inoperable.

Most cars that need an engine rebuild are those that have gone through catastrophic engine failures like overheating conditions or a broken oil pump.

Other causes of engine failure that would require an engine rebuild are:

  • Broken water pump
  • Clogged heater core
  • Broken thermostat
  • Damaged oil pump
  • Low oil level
  • Engine oil is old, too thick, and loses lubricity

These instances would most often lead to car engine damage. An overheated engine would cause head gaskets to fail.

Head gaskets introduce the coolant inside the engine and when they fail to function, the coolant is blocked within oil galleys. The oil then gets diluted, decreasing its ability to produce lubrication for engine parts and cursing excessive heat.

What Happens During Engine Rebuild?

The main purpose of an engine rebuild is to create an engine similar to the new engine a vehicle had when it was purchased or manufactured.

Hence, an engine rebuild most likely involves completely disassembling the engine from what’s commonly referred to as “carb to pan”, an older term used when engines had carburetors instead of fuel injection systems.

Now that cars have fuel injection systems, an engine rebuild involves an “Injector to Pan” process. The pan being referred to here is the oil pan.

When an engine is rebuilt, the following steps are done:

1. Disassembling
2. Cleaning
3. Inspection
4. Replacing all damaged parts with new or refurbished replacement parts like:

  • O rings
  • Bearings
  • Gaskets
  • Seals
  • Timing belt or chain
  • Valve springs
  • Oil pump
  • Camshafts
  • Crankshafts
  • Pistons

5. When the engine is severely damaged, more extensive procedures will be done to make the engine work again. These procedures include:

  • Engine block will be bored to align the crankshaft main bores
  • Cylinders will be bored to fit new pistons

In many ways, an engine rebuild can be a realistic and more cost-effective option. With an engine rebuild, you are assured that your engine has been closely inspected and has been somehow recreated with new parts.

This procedure can significantly lengthen the life of damaged engines while being able to reuse recycled engine parts.

But, the best benefit that an engine rebuild will give you is the connectivity and compatibility with the existing ECU (Engine Control Unit) and electric system of your vehicle.

Engine Rebuild Procedure- NOLA Automotive Repairs

What is an Overhauled Engine?

An engine overhaul is also called a “refresh” because it’s kind of a halfway measure to extend the life of an engine that has miles but is still in reasonable condition.

Most of the time, an engine would need to have its bores checked and cleaned up, along with other typical repairs and adjustments. Some people would call it a budget rebuild.

One way to know if your engine needs an overhaul is if the answer is yes to all of these questions:

  • Does smoke come billowing out of the tailpipe?
  • Does the tailpipe constantly run hot?
  • Does your car sound ‘funny’ at idle or when you turn it off?

Mechanics often suggest an engine overhaul after inspecting the engine and other major components. Never believe a mechanic who says you need an engine overhaul without inspecting first, no matter how experienced the mechanic is. Mechanics always have to look further into your engine before concluding that you need an engine overhaul.

Engine Overhaul Meaning

The term overhaul can sometimes be confused with the terms ‘rebuild’ and ‘remanufactured’.

To make overhaul distinct from these terms, it is used when a mechanic takes care of any failures of an engine doing these things:

  • Lifting the engine out of the car
  • Taking the entire engine apart
  • Cleaning all the parts of the engine
  • Replacing any damaged or worn parts like gaskets or seals with factory-approved parts
  • Putting all parts back together

Engine Overhaul- NOLA Automotive Repairs

This is a typically more extensive, more major, and more expensive undertaking because it involves a lot of cleaning and replacement of most of the parts of an engine. However, there are other types of an overhaul.

For example, mechanics often use other terms for overhaul like “in-chassis” rebuild where only the top part of the engine is fixed by replacing the components like

  • Cylinder liners
  • Pistons
  • Piston rings

An engine overhaul can be your best option when you work with experienced mechanics with proper equipment. The quality of your overhaul will depend greatly on the mechanics who will work on your vehicle.

Engine Overhaul or Rebuild?

When you are not quite sure whether you need an engine overhaul or rebuild, it is best to know the process that is involved in each.

A professional consultation with several trusted mechanics like Nola Automotive Repairs will yield further insights to help you make a well-informed decision.

Contact us now for more information!


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NOLA Automotive Repairs has been serving New Orleans clients for nineteen years, making us one of the trusted auto repair shops in The Big Easy.

We offer a variety of services including engine repair, brake jobs, AC repair, and diagnostics.