One of the most important parts of any classic car is the engine. The car’s engine takes the burning of gas and use that as energy to move the wheels that help drive the car. Without the engine, we are unable to drive our car to work, school, or places that we need to go. In order to keep our engines functioning the way that they should, regular maintenance will need to be performed. While the engines are important and we want to make sure they are in great shape, auto maintenance is something we typically forget to do. For a vintage car over time even the well-maintained car engine can start to develop issues. Sometimes a simple repair can fix the issue, but other times you might need a complete engine rebuilding to solve your car engine problems.
Engine Rebuilding Pros and Cons
A lot of people ask, “What does engine rebuild mean?” and it means that an auto mechanic takes out the entire engine and disassembles it, inspects it, and cleans it, and then replaces any parts that are damaged with new or refurbished parts.
Just like any auto service, there are always pros and cons. If you are needing an engine rebuild, it is good to know what the advantages and disadvantages are.
Engine Rebuilding Benefits
- Less Expensive: Engine rebuilds are going to be a lot cheaper than an engine replacement.
- High Performance: Since engine rebuilds require repairs or complete replacements for parts in the engine, the engine is going to perform a lot better than before.
- Eco-Friendly: Because you are extending the life of your old engine, you are being more eco-friendly because you are cutting down on manufacturing and energy costs.
- Better Fuel Economy: An engine rebuild can help your entire car have better fuel economy since it has been fixed to drive a lot smoother.
Engine Rebuilding Disadvantages
- Take Time: This type of engine service takes at least one to two weeks to rebuild the engine.
- Expensive Depending on Size: While a rebuild is going to be less expensive than an engine replacement, if you have a larger engine or exotic then the rebuild is going to be more expensive.
- Resale Value: If you plan on reselling your car, there are some people who don’t want to buy cars with rebuilt engines.
Engine Rebuilding Vs Replacement
Many people who are having issues with their engine tend to ask if they should get an engine rebuild or replace for their car. It is all going to depend on the extent of damage to your engine. There are a couple of reasons why an engine replacement should be done in place of an engine rebuild. When your auto mechanic takes a look at your engine, they will check to see what shape the engine is in. If there are literal holes in the engine, that is a reason that an engine replacement is needed. If you are driving your car and it stops running and makes a loud noise, that is also a good indication that a replacement is necessary. Also, if an auto mechanic inspects the engine and determines that a rebuild and replacement would be the same cost, it is worth it to get a complete replacement. If you are asking, “Should I replace my engine?” and you have not had your engine maintained in a long time, you have a ton of oil puddles under your car, and there is a ton of noise from your engine, you probably need to go the replacement or engine rebuilding route.
Engine Rebuild Vs Overhaul
How Do You Know If You Need an Engine Overhaul?
We always hear the term engine overhaul and assume that it is a completely different service than an engine rebuilding, but the truth is that it is the same exact service. The reason we are including it is because these terms are used to describe completely different services when they are the same. Knowing when to get an engine rebuild or overhaul can prevent you from getting a complete engine replacement. If you have been noticing that your engine is misfiring, you have a head gasket leak, or extreme oil leaks, it is worth it to take it into a mechanic to see if a rebuild or replacement is needed.
What Does Engine Rebuilding Do?
In some cases, rebuilding an engine can be more affordable and efficient than replacing the engine. In fact, most disastrous engine failures can be avoided through regular maintenance and service checks. One of the principal things that can affect an engine is overheating and a broken oil pump. These two factors will contribute to engine failure. Engine failure will result in a car that is completely defunct. Replacing or rebuilding the engine will be the solution in those circumstances.
Is a Rebuilt Engine as Good as New?
If you are contemplating purchasing a car with a rebuilt engine, it will be important to consider whether the engine will perform as well as a new engine. According to leading experts in the industry, a rebuilt engine can perform as well as an original equipment manufacturer (OEM) engine. In order to ensure that you are receiving a quality restoration, please be sure to investigate the pre-purchase inspection. Even if you are a car expert, you should have an expert and objective mechanic spend some time to go through all the car systems, bumper to bumper. He or she may find something small (or large) that will pop up in a few thousand miles.
How Much Does It Cost to Rebuild an Engine?
In terms of cost, typical engine rebuilding can run you between $3,500 and $5,000 in parts and labor costs however depending on type of engine and damage the costs can go quite a bit higher. While some engine rebuilds consist of replacing the bearing and seals, there are times when the engine must be completely removed, rebuilt, and reinstalled.
Is it Cheaper to Rebuild or Replace an Engine?
There is a simple equation for car owners to calculate when it comes to determining whether they should rebuild or replace their engine. Car owners should calculate and compare the cost of a new or a rebuilt engine through the cost of parts to rebuild, the cost of labor per hour, the hours of labor, and the replacement cost of the vehicle, or the value lost due to downtime. These factors can be boiled down to a simple equation that should be mathematically determined by the car owner. For the classic car owner having the original engine in the car is key to the vintage car’s value so engine rebuilding is the only course of action.
What is Engine Rebuilding?
For older vehicles, engine rebuilding is a part of restoring the car. A rebuilt engine entails removing the engine from the vehicle and completely dissembling it. During this dissembling process, the engine will be cleaned, inspected, and all damaged parts replaced with new or refurbished replacement parts.
Engine Rebuilding: What to Replace
There are a number of parts that should be replaced in the process of replacing your engine:
- Rings. These rings include compression rings and oil control rings.
- Bearings. Rod bearings, main bearings, and cam bearings can all be replaced.
- Freeze plugs in block.
- Head bolts.
- Gaskets.
- Seals.
- And more!
Depending on the condition of the engine, your reputable and established mechanic will have reasons for each replacement part and give a detailed summary.
Engine Rebuilding Without Machining
According to some experts, simply replacing the gaskets and clutch do not entail the actual effort of rebuilding an engine. While it is important to understand that some individuals are capable of replacing the gaskets and clutch, the actual process of engine rebuilding means that individuals will entirely disassemble the engine and replace or repair/clean it piece by piece.
Engine With Machining: Boring, Honing & Balancing
Boring an engine involves using machines to widen and taper the cylinders. From a performance standpoint, boring an engine could give you more horsepower and torque, as it will change the engine’s displacement. Engine displacement refers to the swept volume of all pistons inside the cylinders of an engine.
Modifying and rebuilding engines makes a great passion project for people who love performance vehicles and those who want to breathe new life into beloved vehicles. Working with a machine shop to handle some of the more complicated parts of modifying and rebuilding your vehicle’s engine ensures that the job is done right, as machinists at these shops have expert training and the right tools, components, and car accessories to ensure the precision needed. This is particularly important when it comes to boring, honing, and balancing an engine.
Boring
Boring an engine involves using machines to widen and taper the cylinders. From a performance standpoint, boring an engine could give you more horsepower and torque, as it will change the engine’s displacement. Engine displacement refers to the swept volume of all pistons inside the cylinders of an engine. Displacement impacts how much fuel a cylinder draws in to create power, with high displacement engines drawing in more of the air and fuel mixture per revolution, resulting in a more powerful combustion.
Engine displacement plays an important role in determining how much horsepower and torque your engine produces and how fuel efficient it is. In general, the greater your engine’s displacement, the more power it can create. Lower displacement may result in greater fuel economy.
There is actually a mathematical equation used to calculate displacement:
Engine displacement = π/4 * bore² * stroke * number of cylinders.
Displacement is just one factor that contributes to the power of your engine. Other factors include fuel delivery, valvetrain layout, forced induction, and ignition systems. In some countries, vehicles are taxed based on engine displacement.
With years of use, engine cylinders become worn out as friction stresses cause wear and tear. Boring out engine cylinders helps clear them of debris that can build up over years of use.
Stroking an engine is another method of increasing displacement. Engine stroking allows for greater displacement than boring, but it also requires great precision in picking the right car accessories and parts.
Engine stroking will alter the distance the piston travels in the cylinder bore. By increasing the distance the piston travels in the cylinder, a mechanic can increase engine displacement. Stroking the engine also increases torque by increasing the engine’s crankshaft arm or lever.
Honing
Honing involves using an abrasive to create a precision surface on a piece of metal. Honing is used in a variety of applications, such as finishing cylinders for automotive engines.
For cylinder honing a rotating tool equipped with abrasives to remove metal from the inside of a cylinder. Honing a cylinder helps to finish the surface of the cylinder’s interior to fit a certain diameter and shape. Honing is done after boring to smooth out any irregularities in the cylinder’s finish caused by boring.
Abrasives typically used in honing include silicon carbide and aluminum oxide. These abrasives are inexpensive and versatile. Lately, performance engine builders have increasing turned to diamond abrasives. Engine machinists like these abrasives better because they can hold a cutting edge longer than other forms of abrasives.
Getting honing right is important. A bad honing job may result in improper seating by piston rings that will inhibit oil flow, along with other negative consequences.
Balancing
Balancing your engine is another important part of rebuilding or modifying an engine. Your engine’s balance affects many aspects of its operations, including its:
- Longevity
- Performance
- Power
- Fuel efficiency
- Noise
- Vibration
- Environmental impact
In short, balancing your engine equalizes the reciprocating and rotating forces happening in your engine, allowing it to run smoother and enjoy greater utility and longevity. Many people do not realize that their vehicles are powered by mini explosions (controlled burns) in the engine that occur during combustion. Balancing the engine helps to manage the impact of these reactions.
One of the primary tasks involved in engine balancing is equalizing the weights of various parts. You must equalize the weights of the pistons, wrist pins, rings, connecting rods, rod bolts, and bearings to balance out the forces acting on the automobile’s crankshaft.
Balancing the car engine requires precisely weighing parts to determine which piston and rod are the lightest. Mechanics then machine the other rods and pistons to make them equal to the lightest one in the set.
Next, rotating and reciprocating weights are evaluated in isolation from one another. Once the weights have been determined, bobweights that simulate all of the rotating weight and half the reciprocating weight are put together and clamped on each rod journal. The crankshaft is then placed on an engine balancer and spun.
In some cases, a machinist will try to overbalance or underbalance a crankshaft in order to minimize vibrations and harmonics in a certain rpm range.
Again, it is important to have balancing work done by a skilled professional with the proper tools to ensure a very precise engine balancing job, particularly if you’re making performance upgrades to your vehicle.
Finally
The engine is the heart of all classic cars and when it is not beating properly then the entire car is not performing to our expectations. The process of engine rebuilding is not small task no matter if you are doing it at home as a DIY project or sending it out to a machine shop to perform a full engine rebuilding understanding the process is a key to getting the proper job. By providing the basics to engine rebuilding gives you the knowledge to get to the finish line at a reasonable cost. To help you along the way we have provided an engine rebuilding checklist below:
Master Engine Rebuild Checklist
GASKETS AND SEALS
☐ Head Gasket Kit
☐ Conversion Gasket Kit
☐ Valve Cover Grommets
☐ Front Crankshaft Seal
☐ Rear Crankshaft Seal
CLUTCH AND FLYWHEEL
☐ Clutch Cover
☐ Clutch Disc
☐ Release Bearing
☐ Release Bearing Fork Bolt
☐ Release Bearing Fork Bush
☐ Ring Gear
☐ Pilot Bushing
☐ Speedy Sleeve
☐ Balance Flywheel
☐ Lighten Flywheel
☐ Surface Flywheel
CRANKSHAFT AND CONNECTING RODS
☐ Main Bearing Set (Tri-Metal)
☐ Rod Bearing Set (Tri-Metal)
☐ Thrust Washer Set
☐ Connecting Rod Nuts
☐ Connecting Rod Bolts
☐ Connecting Rod Small End Bushings
☐ Pilot Bushing
PISTONS
☐ Piston Set
☐ Piston Ring Set
OIL PUMP
☐ Oil Pump
☐ Oil Pressure Relief Valve
☐ Oil Pressure Relief Spring
CAMSHAFT AND VALVE TRAIN
☐ Camshaft
☐ Camshaft Bearing Set
☐ Cam Followers (Tappets)
☐ Rocker Arm Bushings
☐ Rocker Shaft
☐ Timing Chain
☐ Camshaft Timing Gear
☐ Crankshaft Timing Gear
☐ Timing Chain Tensioner
CYLINDER BLOCK
☐ Oil Galley Plugs
☐ Freeze Plugs
☐ Lock-tab Kit
CYLINDER HEAD
☐ Cylinder Head
☐ Valve Guides
☐ Inlet Valves
☐ Exhaust Valves
☐ Valve Springs
☐ Valve Seals
☐ Hardened Seats
☐ Thermostat
☐ Cylinder Head Studs
☐ Cylinder Head Fasteners
LUBRICATION
☐ Oil
☐ Oil Filter
MACHINE WORK
☐ Degrease Block
☐ Surface Top of Block
☐ Align Bore
☐ Bore Cylinders
☐ Hone Cylinders
☐ Lap Oil Pressure Relief Valve
☐ Install Camshaft Bearings
☐ Crack Check Crankshaft
☐ Grind Crankshaft
☐ Balance Crankshaft
☐ Install Rod Bushings
☐ Hang Pistons
☐ Resurface Rockers
☐ Fit and Ream Rocker Bushings
☐ Crack Check Cylinder Head
☐ Fit Valve Guides
☐ Fit Hardened Seats
☐ Grind Valves
☐ Surface Cylinder Head
OTHER CONSIDERATIONS
☐ Carburetors
☐ Distributor
☐ Radiator
☐ Exhaust Manifold
ANCILLARIES
☐ Heater Control Valve
☐ Water Pump
☐ Starter
☐ Generator/Alternator
☐ Manifold Studs
Overhaul and rebuild are terms that most people seem to think are the same. In the aviation industry ( I would think in the automotive industry) there is a definite difference.
An overhauled product has been “disassembled, cleaned, inspected, repaired as necessary, and reassembled … and tested in accordance with approved standards and technical data.
A rebuilt product as one that has been “disassembled, cleaned, inspected, repaired as necessary, reassembled, and tested to the same tolerances and limits as a new item.
A rebuilt engine has to be assembled to “new” engine limits and an overhauled engine may be assembled to
“service” engine limits.
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