how to buy a used engine

When your car engine gets damaged, buying a second-hand car can be a good idea but not always. You might think of buy new engine for your vehicle. But sometimes you realize that your vehicle is of the old model and the new engine might not suit you.

The second thing which comes to your mind is to buy a used engine of a car. That is a great idea. But there are certain things which you must consider before buying a used engine. You should check the engine carefully before buying it.

Keeping all these things in mind we have prepared this article that will help you in buying a used engine. Also, it will help you to know how to inspect and check the used car engines. This will also help you know the questions you should be asking the dealer.

How to inspect a used car’s engine condition?

We are here to help you understand the things which you must consider before buying a used engine.

So without wasting time let’s start.

Note Down VIN Number before going to the seller

When you buy a used engine always check the VIN (Vehicle Identification Number) and the engine number of the engine. You don’t have to tell the seller different shapes. Such as how your engine looks like and neither needs to bring your heavy (engine) to the shop. 

If you go to the seller without a VIN number. Then there are a few possibilities to find the exact engine for your vehicle. But after some research, if the seller finds the same size engine, then the least chances to fit your vehicle.

To avoid these situations, VIN and Engine Number help you, to find an engine that will fit in your vehicle. Now, you can bring your used engine for your vehicle, but wait doesn’t bring it now without checking the proper function.

There are many functions are left for checking, let’s do it step by step.

Always buy Complete Assembled Engine

Always buy Complete Assembled Engine

Always buy the complete assembled engine from the seller as it is shown in the image. If you are not a professional in assembling so never buy disassembled engine by mistake. Because there are various types of parts and components in the engine which has a different model. If you are not a professional this will waste your time and irritate you. It may happen from morning to night to assemble it. So the intelligence is to buy a completed engine.

But the topic does not end here. You should check the complete sensors, wiring harness, valve covers, charge pipes, fuel rail, and injectors. Also, check whether their important functions are working or not, like the starter, AC compressor, power steering pump, and alternator.

Also, ask about the history of the engine, and how many kilometers the engine has run. Is the engine faced an accident or not when we’re the last time. It has run and many more questions that come to your mind. These questions will help you to guess the actual condition of the engine. And the important thing to remember doesn’t buy an engine in which standard mileage is below 20000 kilometers per year.

Ask the seller if the engine has a long block or short block.

Both the engines are of the same in size but there are some differences, which we will tell you.

Short Block Engine

The Short Block engine is the end of a vehicle’s engine. It is a partially assembled engine that has the cylinder block below the head gasket but above the oil pan. It includes crank, engine block, connecting rods, and pistons. This engine has a focus on the bottom and end rotating components.

Long Block Engine

The long Block engine is the complete version of the short block engine. It includes a valve train, cylinder head, valve covers, crankshaft and cylinder head, and other components. It does not require the fuel system components such as fuel pump, fuel injector, and intake manifold. This is the completely assembled engine.

Comparison: Long Block v/s Short Block engine

A short block engine has less price than a long block engine. A long block engine has a longer warranty than a short block engine. The long block engine is more reliable than the short block engine because it has more components. And the final result comes out the long block engine is more powerful than the short block engine.

So try as much as possible to buy a long block engine. But to buy a short block engine is not too bad.  

You should always check car engine prices and conditions before buying.

Always try to check the engine in the morning because the engine was at eight or nine hours at rest. Cold investigation can display all hidden problems.

If the engine starts in two or three takes it means that it is in good condition. If the engine does not start in more than three trials, do not waste your money on it.

It will take some time on cold checking. If the engine throws a few white clouds of smoke while starting the engine that’s not a problem. Every used engine suffers from this condition in the beginning.

If you see the engine is exhausting blue smoke and making loud noises that means the engine is burning oil. This happens because of improper maintenance, leaking oil, and not changing lubricating oil and its filter timely. Burning oil can harm the engine or burn the internal components of the engine.

Check properly the engine you are going to buy not consume excess lubrication oil than normal. If it consumes you will see leakage first, but in the case of internal leakage, you are not able to find it.

Bad quality oil, old engine, and high-pressure oil usage are the reasons which force the engine to consume excess oil.

Check the oil leakage in the engine properly

The engine is the heart of the vehicle. The engine oil is the blood, just think if your heart not pumping blood properly what will happen. The same thing in the engine. Avoid the engine if there is a low level of oil. Check the engine carefully under the oil cap after removing it.

To check the oil leakage in the engine. Keep your eyes on the dipstick and check the overflow or low level of oil. When you pull out the dipstick and see there is a lot of black carbon in it. That means the engine has not passed from good services. Oil Pressure Testing is necessary to check the clearance flow of oil. Check the lower part of the engine, everything has to be dry.

Basic Engine Test

All types of tests are necessary to do and the Basic Engine Test is one of them.

  • Check for sludge in the oil. If you see sludge outside of your engine it is a problem. Remove the oil cap of the oil pan, turn on the light, and see inside it. Don’t buy the engine if you see the metallic and silver portion of the engine it represents a sludged engine. A good engine will always be covered with lubrication oil.
  • While performing the cold test with engines try to listen carefully. If you listen to abnormal sounds like two metals are colliding with each other, refuse to buy.
  • Open the engine hood for checking, Air cleaner clogging, Hoses for leaks, gaskets, and valves, improper connections of harness connectors, wiring harness, and vacuum hoses. Refuse to buy if you smell like burnt oil.

Make sure the engine gets a normal temperature while running not getting over. If your engine is overheating in normal weather that means the coolant system of your engine is damaged. If the needle on the temperature pushes its way towards the red zone it may be a sign of overheating.

Don’t forget to check the exhaust fan and whether the other fans are working properly or not. Improper working of fans can create many problems like overheating.

Unusual vibration in the engine may be harmful to your vehicle. About this, we have already told you in Basic Engine Test. This sound can be the collision of metal in your engine and can damage internal parts soon.

If you find some little problem in the engine, tell the seller immediately to repair or replace the faulty part.

Check from Borescope Inspection Camera

A borescope camera will help you to detect the internal failure of the engine’s parts and components such as bearings.

Are your components clean or not? Is there excess carbon or not? All you can see on the screen of the Borescope. Put the wire in parts from where blue light is emitting and it will display the internal conditions of the components. If you do have not this, you can purchase it from the market.

Spark Plug Inspection

Increasing high voltage and the gap of the bridge between the ground electrodes. The center can spark a fire inside the cylinder. And the secondary purpose of Spark Plug Inspection is to help the heat away from the cylinders.

If you see red coating in the spark plugs, this is not a problem. But the spark plug gets too hot which is a sign of pre-ignition damage.

Check Compression on your engine

It will check the condition of your cylinder. If the engine has low compression it causes may be Holes in a piston. The worn timing chain is connected to the crankshaft, and bad piston rings (due to overheating of the engine).

This test will help you to detect the leakage of pressure from rings, cylinders, and valves.

While checking the compression, your engine pressure should be 100 PSI. If it is showing the 10% variation around 100 PSI this is not the issue.

Check the coolant and the other leakages

If you see the coolant leakage from the radiator tell the seller to remove it and place the new radiator. Because sometimes a broken or cracked radiator can create unwanted serious problems. To avoid these situations refuse to buy or remove.

Tell your sellers, that you want to check your engine dry. Because some of the sellers use automatic transmission fluid and thick oil to conduct the compression test which is temporary.

Now you have completely checked the functions of the used engine. But one thing is still left.

After checking the used engine functions properly fix it in your vehicle. Then, take a test drive which will clear the rest of the doubts.

These are some points which will help you before buying used car engines. We hope you like it.


Buying a used engine helps to save you a lot of money and give a new life to your car. After reading this article, you will understand how to buy a used engine and what things you have to keep in mind while purchasing the used engine.

For more information like how to install an engine in a car, you can check the Autotechio website.

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