Hole In The Engine Block – Causes, Signs, & Solutions

Engines can break down in several ways. But in most cases, a hole in the engine block is catastrophic damage that needs the replacement of the engine block or a complete engine. While it is surprising to see a hole in the engine block, it is a pointer that you have a broken component in the engine or other severe issues. The broken parts could be pistons or connecting rods. In other cases, it could be nothing serious.

In this article, I’ll explain what causes hole in engine block, the symptoms to watch out for, and how to fix hole in the engine block. By the end, you’ll learn what to do when you see a hole in an engine block.

how to fix hole in engine block

Hole in engine block symptoms

A cracked engine block or hole in the engine block can sometimes stare you right in the eyes, and you don’t need any other sign that your engine block is cracked. However, there are other signs of a hole in the engine block you should watch out for.

The most common signs of a hole in the engine block are oil leaks, coolant leaks, oil and coolant mixing, low engine compression, overheating engine, too much engine smoke, and visible engine cracks.

Let’s look at the hole-in-engine block symptoms in-depth to better understand when you are dealing with a crack or hole-in-engine block issue.

Oil leaks

Engine oil can leak internally or externally. If your car engine has an external hole, your motor oil will leak out. You’ll see puddles of oil underneath your car when parked or running on idle. Even if the oil leak is not much, check the engine oil with the dipstick. It could be that this has been happening for long.

It could lead to a severe engine breakdown if not fixed on time. However, it’s important to note that engine oil can also leak due to other issues, such as worn drain plugs, loose oil filters, and bristled valve cover gasket.

Coolant leaks

Just like motor oil, engine coolant can leak internally or externally. If there’s a crack or hole in the water gallery area, it’ll cause the coolant to leak out. If you see engine coolant dripping from anywhere on the engine, run a proper diagnosis. External coolant leaks from the engine block can also result from a defective water jacket and lousy thermostat seal.

Oil and coolant are mixed.

If the crack or hole happens internally, it will cause the motor oil and coolant to mix together. If your engine oil is mixing with coolant or you notice motor oil on top of your coolant, that’s a clear sign of a hole or cracked engine block.

Exhaust smoke

Excessive smoke from the tailpipe is another potential sign of a hole in the engine. If the crack or hole happens on the top cylinder, it can cause oil or coolant to drip into the plug hole and foul the spark plugs. Oil-fouled spark plugs will cause a misfire and too much smoke from the tailpipe. If the oil or coolant leaks outside, it can drip on a hot exhaust pipe and cause smoke from the hood.

Car overheating

A hole in the engine often causes coolant leaks. When there’s a coolant leak, you will have little or no coolant in the radiator. And this will lead to an overheating engine. The temperature dial in the instrument cluster will start climbing to the red zone.

Low compression

Fuel and air intake, power, and exhaust stroke cannot start your four-stroke cycle engine. The air and fuel intake must be compressed into a small volume before the power stroke can occur to start the engine.

But if there’s a hole in the engine, the air in the combustion chamber can leak out, causing low engine compression. When this happens, you’ll observe loss of power, engine misfire, and poor gas mileage.

What Causes hole in Engine block?

Under perfect conditions, a hole in an engine is commonly caused by improper or lack of car maintenance, such as running without enough engine oil, which could cause the pistons to break, or using longer spark plugs in an engine that uses shorter plugs, which will cause the pistons to hit on the plug electrodes.

Broken connecting rod

The connecting rod is an essential engine component that connects the pistons with the crankshaft. It is responsible for converting the piston’s linear motion into the crankshaft’s rotational motion to keep the car running.

Like every mechanical car part, the connecting rod can wear out and fail over time. When the connecting rod fails, it can break and throw some of itself against the cylinder walls. This is referred to as thrown connecting rod.

While connecting rods can break due to age, the most common reason why it fails is reving your engine at high speed with low engine oil. A broken connecting rod will cause engine seizure and won’t let the engine turn as you crank it.

Using longer spark plugs

Auto manufacturers design their engines with different technologies. Hence, they require different specifications. Some engines use short spark plug threads, while others use longer ones. Installing a longer spark plug in your engine will cause the pistons to consistently hit the spark plug thread. This will damage the spark plugs and also cause holes on the pistons.

Low engine oil

Most times, holes in the engine block are caused by a lack of proper maintenance culture. All reciprocating internal engine components need an adequate oil flow for proper lubrication. If the engine runs low on oil, it will cause accelerated wear, which could lead to catastrophic issues.

The thing is, low engine oil will not directly cause holes in the engine block. But it can cause internal components to break, which will cause cracks or holes in the engine block.

How do you fix a hole in the engine block?

A hole in the engine is a severe problem you don’t want to deal with because it can lead to complete engine failure. Thankfully, you can prevent the hole from appearing in the first place by cultivating a regular inspection and maintenance culture.

There are several ways of repairing a hole in the engine block. However, the most appropriate and common way of fixing it is using epoxy patching material. This method requires applying the Epoxy patching material over the hole in the engine block, and when dry, it will form a bond that’ll fix the hole or crack in the block. Once done, sand the surface to provide a smooth finish.

However, this approach will not be effective if the hole is too deep or big. In such situations, welders should weld the broken parts to cover the holes. However, you need an experienced welder to do the job because it requires expertise and precision and should be done with extreme caution. This is to avoid causing more damage to the engine block. 

Whether you are asking how to fix a hole in aluminum engine block or repair a hole in cast iron engine block, applying an epoxy over the hole surface is the best solution. But the thing is, fixing a hole in an engine is not an easy task. Plus, it may not always be successful due to the age of the engine and other factors, like how big the hole is.

How much does it cost to fix a hole in an engine block?

Fixing a hole in the engine block costs between $400 to $4,000. If the crack is too small and can be fixed by applying epoxy across the hole or cracked surface, the mechanic will charge you as low as $400. But if the hole is deep or large and requires extensive work, it’ll cost up to $4,000.

The cost of fixing a hole in the engine block can be very bogus at times. Sometimes, replacing the complete engine is better than trying to repair a broken engine block. Contact an experienced mechanic to inspect the engine block and estimate the repair cost. Replace the complete engine if it is close to its shelf life.

Frequently Asked Questions (FAQs)

Is a hole in the engine block bad?

A hole in an engine block is a serious problem that can cause total engine breakdown. It is usually caused by a lack of proper lubrication, broken internal engine parts, and using long plugs on an engine that requires shorter ones. If not ratified on time, it will cause catastrophic damages that will drop expensive repair bills on the table.

Can a hole in an engine block be repaired?

Can you fix a hole in an engine block? Absolutely yes. There are several ways to repair a crack or hole in an engine. The best and easiest way is by applying an epoxy patching material over the cracked or hole area and allowing it to form a bond when it dries up. When dry, sand the patched area to have a finished touch.

Can you drive with a hole in the engine block?

While driving with a hole in an engine block is not recommended, you can drive with it if the crack or hole is too small and there’s no oil or coolant leak. But if the hole or crack is obvious, driving with it can cause a severe engine breakdown.

To prevent costly repairs, I recommend you park your vehicle until you fix any hole or crack in the engine before driving it. This will also save you from being stranded in the middle of nowhere.

Can a hole in an engine block be welded?

Yes, you can weld a hole in an engine as long as the hole is in a weldable area. Welding will make a stronger bond compared to other alternatives. You can weld the hole whether you have a cast iron or aluminum engine block. However, be careful when welding cast iron engines because they are more prone to cracking.

How long does it take to fix an engine block?

It’ll take 4 to 48 hours to fix a cracked engine block, depending on the location and the severity of the hole. If it is a small hole in an open place, you can fix it within 4 hours by applying epoxy. But if severe, you may bring down the engine and disassemble the parts before welding the hole.

Is an engine block expensive?

The engine block is the most expensive part of a car engine. It doesn’t come alone, even though you want to get a used one. The engine block consists of several internal engine parts, excluding the head cylinder.

On average, an engine block will cost you between $1000 and $4000, depending on your car make and model and where you are buying the block from.

Final Words

Aside from engine seizure, nothing is more dreadful than seeing a hole in the engine block. But if you have been reading to this point, you can tell the signs of a hole in an engine block, the causes, and the possible ways to rectify it.

Keep in mind the best solution to a hole in an engine block is to replace the engine block or the entire engine. Meanwhile, it’s your money, your car, and your decision.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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