A blown-out engine could be the end of the road for your automobile if it’s an old clunker. However, if it’s not that old, you may want to consider buying a replacement motor. In this article, we’ll explain how to determine if the busted engine is dead, discuss some of the causes why the engine fails to crank and address if it can be repaired. We’ll also examine the options of trading or selling a car with engine problems.

If you have a vehicle that’s rolled up its last hill, whether a newer model or 15 years old or more, here’s the information you need to help you decide whether to replace that 4, 6, or 8 bangers, sell it, or trade it.

Make Sure Your Car Has a Blown Engine

A blown engine means your vehicle isn’t going anywhere under its own power. There are often several indicators that your motor is damaged or has problems before it completely fails. If your car’s motor blew up, there’s a high probability that the engine block is cracked or broken.

The engine block

The engine block is a solid cast ‘block’ of iron or aluminum with smooth cylinders cast inside it. The pistons with their rings slide up and down inside the cylinders, and oil minimizes the friction of the moving components. At the bottom of the block are the oil pan or reservoir and the crankshaft. The oil lubricates the moving parts. The pistons turn the shaft on their downward thrust. Then the spent pistons are pushed back up.

The downward thrust is created by an explosion of compressed gasoline and air ignited by a spark plug. The heat generated by the explosion and friction radiates into the metal block. Water channels are cast into the block to prevent overheating. The channels are known as the water jacket, and coolant travels through, absorbing the heat. The coolant moves through the block and into the radiator for cooling before returning to the block to repeat the cycle.

The oil lubricating and coolant systems are vital to the engine’s continued operation. If you start having problems with either, it’s time to act before the engine block is severely damaged.

Mixing of oil and antifreeze

When you change the oil, or it puddles on the ground, it is commonly medium brown to black in color. If it is cloudy white, you know antifreeze is mixing with oil, a sure sign of a crack.

Oil pressure

A drop in oil pressure indicates that something is wrong with the motor. It often means there’s dirt blocking the oil pump pickup, there’s a busted head gasket, or a leak somewhere. A large puddle of oil under the front of your car, no oil on the dipstick, and when you attempt to start it, you hear metal grinding on metal are sure signs you have a cracked block.

Loud sounds from under the hood

A blown motor sound is impossible to notice. You will hear a loud grind sound due to the increased friction, usually because your car is leaking oil. This is one of the best indicators of a motor blown in a car. If you hear a metallic grinding noise coming from the engine when starting or cruising, it is likely a mechanical issue caused by low or no oil to lubricate the moving metal parts.

Engine frequently overheats

If the coolant temperature gauge on the dash indicates the engine is overheating or there is white smoke billowing out from under the hood, you need to check the coolant system. Wait for it to cool down first. If the smoke is coming through the side of the block, there is likely a crack.

Check the antifreeze level, make sure the rad isn’t blocked, and the hoses aren’t damaged or leaking. If those are fine, check the water pump, pulley, and belt are working as they should. If you’ve done all that, and the engine still frequently overheats, and you have to add antifreeze repeatedly, take it to a mechanic.

Poor compression

A crack in the block can compromise the cylinder walls and result in poor compression. As the piston moves through the compression part of the stroke, the gas-air mixture escapes through the fissure. The result is little or no combustion to drive that piston on the power stroke.

Smoking engine

A smoking engine is a sure sign of a problem, especially if combined with other indicators. The exhaust goes out the tailpipe, so smoke under the hood means something is wrong. Bluish, dark gray, or black smoke combined with low oil pressure, rough idle, or loss of power usually means an oil leak and likely a damaged block. If you observe the smoke escaping from the block itself, there is cause for concern.

The block has a visible crack

Checking out the block for a crack may sound simple until you open the hood and start looking. The engine block is often obscured by other components and cables, making a visual inspection difficult.

You may observe smoke or fluid stains or be able to feel the crack—never put your hands near the engine when it is running or hot. You may see smoke escaping from the side of the block, which will assist in locating the crack. If the crack is large enough to see, it’s time to consider your options.

What Causes a Motor to Blow?

Cars and trucks are mechanical beasts with high-performance engines. They commonly operate for hundreds of thousands of miles with comparatively little maintenance. However, there are several symptoms that, if ignored, can cause an engine to blow.

Lack of maintenance

Low oil pressure, frequent overheating, worn hoses, and belts can prevent your automobile’s oil and coolant systems from working. A water pump or pulley failing can also cause overheating, as can a damaged radiator. Regular maintenance and using the recommended fluids will prolong the engine’s life. Changing the oil, flushing and replacing the coolant, replacing worn belts and hoses, maintaining the water pump and pulley all help maintain the motor.

Overexertion on the engine

Making the motor work beyond its power range will cause damage. Hauling excessive loads behind a 4-cylinder, uphill and down, will blow the engine. It can also do the same to more powerful 6- and 8-cylinder workhorses. Adding lifts and oversized tires can also cause overexertion and engine failure.

Engine failure can also be caused by running an engine at high speeds and at excessive revolutions per minute (RPMs) for an extended period of time. To save the engine from wear and tear, ease off on the gas and aim to drive at cruise speeds.

Engine modifications

Modifying an engine with a turbo or supercharger that isn’t compatible can blow the motor. The increased power generates more heat than the coolant system is designed for. The excess heat can make the block break or crack.


The coolant used in an auto is rated for different operating temperatures and climate temperatures. Diluting the coolant with water or a differently rated coolant can cause the block to crack. Cold climate coolants stay liquid at extremely low temperatures, whereas warm or summer weight liquids can freeze. If the coolant freezes, it can crack the block.