Engine overhaul guide by expert mechanic

Engine overhaul is tantamount to giving your engine a new life. Automobile engines are generally built to be strong and long-lasting. They are renowned for generating and delivering power as well as efficiency.

Like in all car components, however, mechanical problems (and even electrical) are ultimately going to arise one way or another. There are several components and a number of factors that can be responsible for an engine's loss of power and performance. Sometimes, it's just one thing.

At other times, it's a combination of factors. In any event, it's essential that you promptly deal with arising engine issues to prevent worsening the issue. If left unchecked long enough, it can lead to total engine shutdown.

Engine overhaul

A complete engine overhaul can, most times, help to solve these problems and prevent further mechanical damage. Apart from that, an engine overhaul offers numerous benefits for your engine, and car in general.

From increasing its life to vastly improving general car performance. You want to pay attention when your car produces excessive and colored smoke or your engine starts to sound weird. An engine overhaul performed by an ASE-certified professional may just be what you need.

This article will extensively discuss engine overhaul, from the process to the several benefits. Also, frequently asked questions about engine overhaul will be answered.  

What is an engine overhaul?

Engine overhaul repair kit

An engine overhaul is a major engine repair that consists of dropping, disassembly, detection, cleaning, and wholesomely fixing the problems of an engine. Small parts and components such as bolts and oil may be replaced with new ones. The cleaning is to effectively remove years of accumulated debris and grime.

Once the process is completed—all malfunctioning parts replaced, all areas cleaned—the engine is reassembled. Then, lifted and out back into the vehicle. Engine overhaul is the go-to solution for general engine maintenance.

They will most likely advise you to consider it when your car engine starts to act funny. It's important that you take his advice only when it comes from a professional mechanic.

Go for engine overhaul if, after a meticulous check-up, they are certain that it's what your car needs. Your engine will be dropped, taken apart, cleaned up, with all damaged parts replaced before it's reassembled like it's new. This is an engine overhaul in a nutshell.


You may not need to overhaul everything if the problem is minor. In which case you would have to settle for a partial overhaul, also known as in-chassis rebuild. Your mechanic won't have to take down the whole engine for overhauling or repair.

Only some components of the engine such as piston rings and cylinder liners are replaced. Just like engine overhaul, the in-chassis rebuild will help to get your engine back on the road delivering better performance.

Benefits of engine overhaul

benefits of engine overhaul

An engine overhaul is an excellent solution for car engines that are not out of commission. The best chance for them to feel brand new is overhauling. Give or take, a good engine overhaul will last 5 years or more. The following are some benefits if you go through with it.

It's a one-stop solution

Engine overhaul will effectively fix any engine problem you are having. From excessive smoke billowing from your exhaust to shavings in your engine oil to unappealing engine sounds and overheating. It's like troubleshooting, but with surer and more practical results.

It will save you money

An engine overhaul is an effective way to save money. Instead of fixing one engine problem after the other, you get to do everything once and for all. You save the money you would have spent on several repair rounds. Also, engine overhaul solves problems that would have otherwise worsened early enough. You save money by preventing engine components from going from bad to worse.

It will enhance overall performance

Engine about to be overhauled

Remember that the reason for engine overhaul in the first place is the various symptoms of engine malfunction. This would, no doubt, reduce the engine's performance. However, thoroughly inspecting, cleaning, and replacing these components during overhaul will solve the performance problem. To put it simply, an engine overhaul increases the efficiency of your engine.

It offers a chance to upgrade

You can decide to include new and improved features in your engine in the process of overhauling it. You may want to increase the speed capacity or power delivery. Car owners and drivers do this every time to improve car performance and efficiency.

Your engine will have better mileage

Most of the engine malfunction symptoms already mentioned in this article inadvertently worsen fuel consumption and car mileage. But while an engine overhaul will solve power and noise problems, it will also improve your car's fuel consumption and vehicle's longevity.

Note: Finding a professional mechanic to do your engine overhaul is not enough. It's prudent to find one that deals particularly with your car type. This is a hack for getting the most out of your overhauling experience.

What are the processes involved in engine overhaul?

Talking generally, it involves the following:

1. Preparing to remove the engine

Preparing to remove engine

To comfortably work on the engine, you will have to disconnect, remove, and place it on your workbench. But first, you prep the engine for removal.

  • Disconnect and keep the wire of the spark plug.
  • Drain the fuel or detach the whole fuel tank.
  • Drain oil from the engine’s crankcase (replace it with new oil when you finish).
  • Clean the exterior of the engine.
  • Disconnect any throttle and anything driven by the crankshaft.
  • Remove any auxiliary drive.

2. Remove the engine

Removing engine

If you’ve done the step correctly, the engine should be free to move. You can now move it.

3. Disassemble engine

Disassemble engine

You can now begin to disassemble the engine and begin overhauling. Start by removing accessories like the oil filler pipe. Move on to work on the carburetor, muffler, flywheel, ignition, cylinder head, valves, oil sump, camshaft, connecting rod, piston, crankshaft, oil seals, breather, and the rest. Inspect all the components, repair and replace damaged or faulty ones as the case may be.

4. Reassemble and install the engine

Now that the engine overhaul is complete, reassembly and installation are what’s left. Do this and you will have a better, working engine.

What can lead to engine overhaul?

All car engines are supposed to function optimally at all times. This is a performance and safety rule. However, this is often not the case. Car engines may function well after the first few years of purchase and use.

But that soon changes with time and mileage. The problem that may arise with your engines later may only require minor repairs. And sometimes, overhauling may be a more lasting solution. This section will talk briefly about the 5 signs that should prompt you to overhaul your engine.  

Low oil pressure

Low oil pressure

Your engine will consume more oil than normal if your engine's oil pressure is low. This is never a good sign. Why? The oil keeps the required components of your engine well fabricated and functioning optimally. This problem, however, might cause it to leak out through the piston rings, consequently damaging the aging bearings and valve guides.

Excessive smoke from the exhaust pipe

Excessive smoke from the exhaust pipe

An increase in exhaust pipe smoke, especially colored smoke, generally signals trouble in the engine. While white smoke may mean that an interior coolant is leaking, black smoke would indicate that too much fuel is being burned. Blue smoke, on the other hand, shows that too much oil is being burned up. All of these can cause a lot of problems for your engine.

Decreasing fuel mileage

Admittedly, several things can cause poor fuel efficiency. Take your car to your mechanic to quickly detect the source of the problem. It, however, won't be a surprise if an engine overhaul can solve the problem.

Black deposits spark plugs

Bad Spark Plug

Dark, damp discoloration can begin to appear on your spark plug when you pull them out. You may have to replace the engine’s intake valve guides. Do the same if you notice decaying piston rings. Delaying is how oil leaks into your combustion chamber.

Lost compression

A blown head gasket is usually responsible for an engine’s loss of compression. Worn exhaust valves, damaged cylinder bore, and a number of other internal issues may also be responsible. An engine overhaul can fix everything.  

Blown top gasket

Weird engine sound

This is when your car engine starts to make funny noises. Take your car for inspection the moment it stops sounding normal. You need to know exactly what's wrong. A knocking sound, for instance, may mean too much clearance between the pistons and its cylinder bore. Rattling and chattering sounds may indicate broken piston rings and damaged valve-train respectively. Meet your mechanic to be sure which is the case.


Engine overhaul can be will happen eventually if you use your car long enough. If done properly, it can make your car perform as though it were brand new. The first thing to do when you make up your mind to go through with engine overhaul is to pick a professional mechanic who has experience. Half the job is done. All that's left is for you to take your car in.

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