How To Unseize an Engine? Everything You Should Know 

The importance of regular car maintenance cannot be overemphasized. Your vehicle’s overall performance relies on regular maintenance. As simple as a motor oil change is, it can make a huge difference and prevent unnecessary car engine repair.

If you fail to change your engine oil as recommended by the manufacturer, it will cost several problems in the long run. It may cause engine seizure, requiring overhauling or replacing the engine. If you do not imbibe a regular maintenance culture, you’ll want to start your engine one day and discover that it has seized.

If you find yourself in this situation, you may wonder what causes engine seizures. Here, we’ll explain how to unseized an engine, how to check if the engine is seized, and how to prevent engine seizures.

engine seized from sitting

What causes the engine to seize?

Before you can fix any problem, you need to understand the actual cause of the problem. Here are the probable causes of engine seizure you need to know and navigate to when tracking the root cause of the problem.

Low engine oil

Undoubtedly, the low engine oil will cause engine overheating and increased friction in the engine. The motor oil is a lubricant that prevents excessive wear on the internal reciprocating engine parts.

It also serves as a layer that separates the cylinder walls and the pistons, hence preventing overheating and friction. Driving with low engine oil will cause excess wear and increased friction, leading to a catastrophic engine breakdown or seizure.

Water in engine

Coolant and oil move in various engine compartments to lubricate and cool the system, but they have different passages. If water enters the wrong passage for any reason, it can seize the engine instantly or in no time.

Water can enter the engine in two ways; through flood or a blown head gasket. If you drive your car in a flood or water puddles, the water may enter the engine through the air intake. If this happens, the engine will seize immediately, depending on the amount of water.

On the other hand, if the water enters through a blown head gasket, you will notice coolant in oil when you open the valve cover or observe oil in coolant when you open the radiator cap. Either way, this can cause the oil to lose its lubricating properties, causing increased friction and eventually leading to engine breakdown.

Engine sludge

Engine sludge can build up if you do not change your oil regularly. Also, rust can accumulate over time if you park your baby ride for long. Any of these can seize the engine. In addition, rust can come from the gas tank, and that is why you need to check and clean the tank regularly, especially when working on the fuel pump.

Another area you should always inspect is the fuel filter. A clogged or dirty fuel filter can transport rust and dirt to the car engine. Although, a dirty fuel filter has obvious signs like rough idling, engine misfiring, hesitation, or stuttering that will force you to trace and replace the dirty fuel filter.

Improper oil circulation

Motor oil is the lifeblood of an engine. Like the human blood in our bodies, your engine oil needs to circulate properly. Reciprocating engine components need adequate lubrication to run properly. And if they have improper oil circulation, it may cause the engine to seize up.

A common sign of improper oil circulation is the illumination of the oil light on the dashboard. Improper oil circulation happens when you have a weak or failing oil pump. If this is the case, and you’re asking how to unseized a small engine, all you need is an oil pump replacement.

Damaged or broken engine parts

Internal engine parts like pistons, connecting rods, and other parts can break or become faulty. If this happens, the car will not crank fully and will not start. While this is not common, it can happen in some cases.

Vapor lock

Another probable cause of engine seizure is vapor lock. This occurs when your diesel engine becomes too hot, causing the diesel fuel to be converted to gasoline. Of course, diesel engines cannot work with gasoline.

A common sign that this has happened is when your engine sputters and dies off shortly. This mostly happens to old diesel vehicles that have been in the sun for a long period. Don’t worry; we’ll explain how to unseized diesel engines in the subsequent sections.

How to unseized an engine

Regardless of why your engine is locked up or seized, there are possible ways of unseizing it. In extreme cases, it may require rebuilding or replacing the engine. You may wonder how to unseized an engine from sitting or how to unseized an engine that ran out of oil if your engine is seized up due to long sitting or lack of oil.

Confirm if the engine is seized

First, you need to confirm if the engine is actually locked up in the first place. If you’re working on a small car engine, remove the spark plugs and try to turn the engine with a sizable wrench and socket.

If the engine fails to turn by hand, it’s locked up. If you’re working on a big vehicle engine, try turning it with a breaker bar and see if it will turn. This explains how to check if your engine is seized.

Unseizing a locked engine from sitting

Assuming the car engine is locked up from sitting, you need to get one of the best penetrating oil for seized engines. A good penetrating oil will do its magic, especially if your car is seized from sitting in the rain, where water may have mixed with the engine oil and gum the piston rings to the cylinder walls.

Get a reliable penetrating oil. If you don’t know any, go for P’Blaster. Shoot a large amount of the oil into all the cylinders through the spark plug holes. Ensure you put on your protective gear, especially eye goggles, to prevent the oil from shooting back and hitting you in the eye.

Let’s be honest; you need to invest your time here because it requires patience. Apply the penetrating oil every day or once in two days for two weeks. Carefully tap the pistons with a long screwdriver and a tapping hammer whenever you shoot in the penetrating oil. This helps to loosen the rust holding the pistons against the cylinder walls.

Try to turn the engine pulley each time you apply the penetrating oil. If the engine is still seized after two weeks, repeat the cycle for another week or two. You should be able to turn the engine by this time. However, if it’s still locked, you have a serious case that needs a mechanic’s attention.

Unseizing a locked engine caused by water in the engine

Water in the engine is a common cause of engine seizures. As reiterated above, water can enter your engine in two ways: air intake and a blown head gasket.

Assuming your engine seized while driving in flood, and you didn’t crank it repeatedly, it may not damage anything. All you have to do is to remove the water from the engine.

To do this:

  • Roll the vehicle to a safe place or tow it to a garage.
  • Get the necessary tools and remove the intake manifold, exhaust manifold, and spark plugs.
  • Turn the engine pulley by hand and see if it will turn. If nothing is damaged, the engine will turn once you exert force on it.

The engine will vomit water from both the intake and exhaust sides of the cylinder head. Keep turning the engine until it starts turning freely and there’s no water coming out from the exhaust and the intakes. After that, reinstall everything you removed earlier following the reverse process.

The engine should start at this point. However, If you do not remove the water immediately and leave it for a couple of weeks, you will likely find it difficult to turn the engine. Here’s why I said so, the water may have caused rust on the reciprocating engine parts. In any case, all hope is not lost.

You can use transmission fluid to unseized the engine by pouring the fluid into the plug hole. After pouring the fluid in all the plug holes, allow it to sit till the next day. If you’re lucky, the engine will turn the next day.

I know you’ll wonder, what if the water enters the engine through a blown head gasket? What if it is caused by a broken or bent part? What if the engine is seized due to improper oil circulation? All these problems require a single remedy – engine overhauling.

Overhauling the engine

You need to overhaul your engine if water enters it through a blown head gasket or the engine is seized due to a broken part or improper oil circulation. Unfortunately, this requires disassembling the entire engine components to determine and replace broken, bent, or burnt ones.

Engine overhauls are best left for experienced gearheads. So, you have to contact your mechanic. Unfortunately, this is one of the most expensive car repairs. It will leave hundreds if not thousands of dollar repair bills on the table.

Overhauling the engine

How to prevent engine from seized

No doubt, prevention is better than cure. Avoid engine seizure by following the manufacturer’s scheduled maintenance. Pay attention to the dashboard lights and your engine sounds. If you notice and replace a failing oil pump on time, it will not cause additional problems.

Similarly, if you always pay attention to your engine sound and detect and fix unusual sounds at the early stage, it won’t cause catastrophic damage. Contact your mechanic if you hear a strange noise or see an unusual light on the dashboard. They should know what to do and prevent the issue from escalating.

FAQs

Q: What is the best fluid for Unseize an engine?

There are several penetrating fluids in the market you can use to unseized an engine. But you have to be smart when selecting the best penetrating fluid to unseized a locked engine. If you buy the wrong fluid, it may not work or cause more damage to your engine.

The best penetrating fluids you can get are penetration catalyst blaster 16-PB, Liquid wrench L16 penetrating oil, and Kano Aerokroil penetrating oil. But, of course, there are other good ones out there.

You can select one from the ones listed above if you don’t know the one to buy. However, if you don’t have the extra bucks for a penetrating oil, get a 50/50 mixture of transmission fluid and acetone.

Q: Can you fix a seized engine because of no oil?

No matter the cause of an engine seizure, there are probable solutions to rectify the problem. However, if your engine seizes because of no oil, there are limited and expensive solutions to resolve the damages. In this case, the engine may have incurred catastrophic damages and requires rebuilding, salvaging the parts you can, or replacing the entire engine.

Q: What happens if your engine locks up?

Assuming your engine seizes while driving, it’ll make a loud sound, and the vehicle will stop on that spot. It will not start until you track and fix the root cause of the problem. However, this will not prevent the vehicle from rolling, assuming you’re on a steep hill or pushing it.

Secondly, the crankshaft will not turn when you try to turn it by hand. However, kindly note that your engine can partially or completely seize. In case of a partial lock, the engine will turn to a certain point and stop.

It will also return until it gets to that same point. A partially seized engine is mainly caused by bent or broken internal engine parts. A Completely seized engine will not turn at all.

Q: Will a seized engine still crank?

No, a seized engine will not crank. Of course, the most common sign of a seized engine is the inability of the engine to crank. If the engine is partially seized, it’ll slightly turn to a certain point whether you’re turning it by hand or with the ignition key. But it won’t crank normally or start.

Q: How much is it to fix a seized engine?

Since several issues can cause an engine to seize, it is practically impossible to give an accurate repair cost without a thorough diagnosis. However, if your engine is seized due to long sitting or water entered through the intake manifold, you can fix it with around $300 to $1,000.

But if it happened due to lack of oil or improper oil circulation, you likely have bent or broken internal engine components. This will take you around $1,500 to $5,000 to diagnose and resolve the problem.

Final words

Engines can seize for several reasons. And there are several ways to unseize it, depending on the root cause. This article has outlined the possible causes and several ways how to unseized an engine.

If the engine locks when driving in flood or due to long sitting, you could try to fix it yourself. But if it happens due to no oil or improper oil circulation, you need to contact a certified mechanic to diagnose and fix the problem.

Osuagwu Solomon

Osuagwu Solomon is a seasoned automotive technician for the past 9 years, and a technical writer. He loves writing about auto professional repair guides, DIY repair guides, and buyer’s guide. After spending six years in the automotive workshop, he decided to impact his knowledge to people aside his domain, and he has achieved this by centering his Automotive writing skills on REPAIRS.

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