A Comprehensive Guide for Car Engine Overhauling: Here’s What You Should Know

Author: Jeo George•Published on: 1/2/2026•6 Minutes
Overview:While there has been a rapid increase in new car sales in recent times, there is also a section of people who prefer to buy a used car or continue using their old cars after restoring them. For people belonging to the latter category, trends like engine overhaul and repainting are on the rise, which gives their cars a fresh, new look and feel. Even for new car buyers, there is a need for engine overhauling – either small-scale or extensive - at certain stages, which are essential for prolonged smoothness, efficiency and performance. A need for engine overhauling arises from a recommendation in maintenance schedules or a sudden fault that occurs while driving. Here, we will be discussing why and when there is a need for engine overhauling, along with its types, benefits and steps involved in the entire process.
Share this article

Key Highlights:


  • There are two types of engine overhaul: top overhaul and full overhaul, the latter of which requires more extensive work.
  • Engine overhauling improves both fuel efficiency and performance, while also enhancing the life expectancy of the engine.
  • Engine overhaul costs ₹20,000 to ₹2 lakh, depending on the car brand and the amount of work involved.




Signs of Engine Overhaul


Whenever something goes wrong with its engine or it requires an engine overhaul, a car gives a few early indications, neglecting which can lead to more expensive scenarios, such as complete engine seizure. These early indications of your vehicle requiring an engine overhaul are:

  • Dark blue or black smoke from the exhaust pipe
  • A sudden drop in fuel efficiency or performance (or worse, both)
  • Increase in engine oil consumption
  • Frequent instances of overheating
  • Warning lights are popping up in the instrument console
  • Strange noises like knocking or tapping from the engine bay
  • Engine oil leakage

Types of Engine Overhaul


The extent of engine overhauling is classified into two different categories:


Based on the amount of work


Top Overhaul
The most basic form of engine overhaul, top overhaul includes the repair or replacement of only the upper components of the engine, including cylinder head, valves and camshaft. These components are affected in case of a head gasket failure or low compression.


Full Overhaul
This form of engine overhauling involves the repair and replacement of components in both upper and lower halves of the engine, including parts such as pistons, connecting rods and crankshaft.


Based on the type of work


In-Frame Overhaul
In this version of the overhaul, the engine remains attached to the vehicle's frame. The repair work is carried out on the engine while it is still attached to the frame. It is preferred in large commercial vehicles such as trucks and buses.


Out-of-Frame Overhaul
In this version of engine overhaul, the engine is first detached from the frame and taken out of its bay, after which the repair work begins. This practice is more common in all passenger cars and SUVs.


Steps of Engine Overhaul


The entire time-consuming process of engine overhauling, one which requires the most extensive and skilled human labour, consists of the following steps:


Identification of the Problem
Technicians detect the root cause of the problem in a diagnosis or technical inspection.


Dismantling of the Engine
In the event of a top overhaul, only the upper components of the engine are dismantled. However, if a full overhaul is required, the engine is detached, after which its components are dismantled one by one.


Cleaning of the Components
The dismantled components are cleaned to remove debris and dirt accumulated on them. To clean these components, technicians use high-pressure water or solvent oil.


Replacement or Repair
After cleaning the affected component, the technician first analyses it for a possible repair. However, if it is beyond repair, it is replaced by a new component.


Rebuilding
After the repair/replacement of the affected product, the technicians reassemble the engine one by one.


Testing
In the final stage of the engine overhaul, the technician takes a test drive of the vehicle to check if the problem persists.


Benefits of Engine Overhauling


While engine overhauling sounds like a complex idea, its benefits can’t be ignored, which are as follows:


Improvement in Performance and Efficiency
Since the internal components are cleaned or replaced during engine overhauling, the engine functions smoothly with fewer frictional losses. With this, there is a notable improvement in both performance and efficiency.


Enhanced Life and Reliability of the Vehicle
Engine overhauling replaces worn-out components with repaired or new components that operate with higher efficiency, resulting in lower chances of failure or more significant damage. It eventually enhances the engine's durability and makes it run optimally for an even longer time.


Cost-Effectiveness
Compared to an entire engine replacement, which is a much more expensive process, engine overhauling addresses only the faulty component and requires its repair or replacement, lowering the costs involved. It is also a more sustainable and environmentally friendly solution compared to engine replacement.


Improved Safety
The early detection of a potential problem in the engine, which requires engine overhauling, can save the driver from risks such as engine blasts and severe malfunctioning.  


Costs Involved in Engine Overhaul


Given the extent of labour work involved, engine overhauling is not a cheap procedure. For mass-market vehicles, the charges of engine overhauling usually range between ₹20,000 and ₹2 lakh, with the following factors affecting the final cost of the process:

  • Type and brand of the vehicle
  • Cost of spare parts
  • Skill level of labour

In the case of luxury cars and SUVs, engine overhauling costs can stretch to an even higher level


When Your Engine Struggles, Overhauling Delivers


Engine overhauling is a comprehensive yet effective solution, whether you're facing a sudden drop in performance, efficiency, or even a potential threat to engine durability. Although it’s not an inexpensive process and demands skilled workmanship for proper execution, the benefits are substantial. Once completed, an overhaul gives your engine a renewed lease on life, often resulting in noticeable improvements in its performance and reliability.


FAQs


1. What is the process of overhauling?|
Engine overhauling is the process of repairing or replacing one or more faulty or worn-out components of the engine to improve its durability, performance and efficiency.


2. What are the two types of overhauling?
Engine overhauling is classified into two categories: top overhaul and full overhaul. While a top overhaul involves only the upper components of the engine, the full overhaul includes the internal components of both upper and lower halves of the engine.


3. What are the steps for an engine overhaul?
The step-by-step procedure of engine overhauling includes detecting or diagnosing the problem, dismantling the engine, cleaning the components, repairing or replacing the faulty part, reassembling the engine, and finally conducting a test drive of the vehicle.