What Are the Benefits of Having an Engine Rebuilt Instead of Replaced?

Most catastrophic engine failures can be avoided through routine service and maintenance. In most cases, an overheating condition or broken oil pump will cause internal components to fail, which can result in a non-operable car that will require a new engine or engine rebuild.

Although it might seem easier and more cost-effective to replace your older engine, the truth is that even if the replacement engine is from the exact same car as yours, there could be many potential hurdles to overcome.

Listed below are a few of the things to consider when you're in the market for a new engine or having your existing engine rebuilt by a professional engine mechanic.

What are the most common causes of engine failure?

In most cases, engine failures are caused by one root source: heat. Whether it's a failure of the cooling system to keep the engine at an optimal operating temperature, or a lack of oil pressure or clean oil to lubricate moving parts which creates excess friction, most major engine failures can be traced back to these events. In general, there are a few specific issues that lead to engine failures including:

When any of these occur, different parts of the engine will become damaged. If the engine overheats, it's common for head gaskets to fail which introduces coolant inside the engine block within oil galleys. This dilutes the engine oil and causes a lack of lubrication, or excessive heat.

Knowing what caused the engine to fail is the first step in determining whether or not an engine rebuild or replacement is needed.

What Happens When an Engine is Rebuilt

A rebuilt engine involves removing the engine from the vehicle and completely disassembling it from what's commonly referred to as "carb to pan". This is an older description when engines had carburetors instead of fuel injection systems they have now, so today it would be referred to as "Injector to Pan," with the pan being the oil pan. Once the engine has been disassembled, cleaned, and inspected, all damaged parts are replaced with new or refurbished replacement parts. All new gaskets, seals, and lubricants are used in the assembly of the rebuilt engine that will meet OEM standards.

The most common components to be replaced include O rings, bearings, gaskets, seals, timing belt or chain, valve springs, and the oil pump. Major parts are replaced only if they are needed, and often include camshafts, crankshafts, and pistons.

If severe damage occurred to your engine, the engine block may have to be bored to align the crankshaft main bores. The cylinders may need to be bored to fit new pistons. This is more extensive work, but it will allow the engine to work once again. In general, there are only two instances where the choice is not an option.

*The engine block has been damaged internally due to broken connecting rod or crankshaft

*The exterior of the engine block has been cracked or "windowed" - which happens when an internal component punches a hole in the block.

Under other issues, having the engine rebuilt is a realistic option

The Advantages of Rebuilding

Once the engine is rebuilt, you know everything has been closely inspected and it has many new parts. It will extend the length of life for the engine. How long it will last depends on how many components were replaced. Another benefit is that you are recycling engine parts to help reduce the amount of scrap in the environment.

However, arguably the best benefit of engine rebuilding is the connectivity and compatibility with the existing ECU and electrical system. The ECU is programmed to communicate with the engine originally installed in the vehicle. In many cases, when a new engine is installed, the ECU has problems connecting and communicating with the new engine. In most cases, an engine swap will require either a reprogramming of the ECU or replacement.

If you have the opportunity to choose between a repair or replacement, it is always advised to repair the existing engine with new, OEM replacement parts to reduce the potential of compatibility issues.


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Ford Fusion L4-2.0L Hybrid - 75 Point Safety Inspection - San Jose, California
I have ordered a 75-point inspection of the car since my dealership claimed it had an oil leak and the timing cover replacement was due (this kind of repair costs in the ballpark of a thousand dollars). I mentioned the need for a second opinion on that since the car had been bought relatively recently from that dealer (certified pre-owned) and not very actively used. Pradeep performed the safety inspection in a very timely manner and addressed my main question by honestly concluding that there was no leak but just some dust collected over time. This has saved me much time and money. Finally, I was also very glad to learn a tip on how to find a matching paint for a body scratch from him.
Ford Escape - 75 Point Safety Inspection - San Jose, California
Pradeep immediately found the suspension problem I was worried about and fixed it. We had just purchased this car and now feel a lot better about it now that he has checked it out.

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Honorio not only told me what is going on with the car but was so honest about everything. Looking forward to having Honorio taking car of my requests.
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