If you notice any symptoms of a seized engine, you shouldn’t try to drive your car. If the engine locks while driving, promptly put your hazards on, pull over, and stop without delay.
When it comes to the automotive world, a seized engine is pretty much as bad as it gets. You’ll have almost no control without the motor propelling your vehicle. The engine will be impossible to restart, and you’ll probably need a replacement.
Within your motor, there are many moving metal parts. The crankshaft, pistons, connecting rods, valves, and camshaft, to name a few. If just one of these stops working, it could quickly lead to a seized engine.
Cars are a feat of intricately designed engineering, but something will always go awry.
If you notice any signs of your engine being about to seize (explained in this guide), you should stop driving and turn your vehicle off as quickly as possible.
In this guide, I will explain the reasons behind an engine seizure and suggest how you can fix it.
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What Are The Symptoms Of A Seized Engine?
The parts within the motor become physically stuck, leading to much more damage throughout the block. This damage can also transfer through the rest of the drivetrain, causing untold amounts of destruction.
Needless to say, a locked engine is a severe crisis with potentially dire consequences. Here are some of the main symptoms of an engine seizing.
Loud Knocking Sounds
Engine components are smashing against other parts they aren’t supposed to be hitting. This creates a cacophony of terrible-sounding noises that will rapidly get worse and worse.
Expect the knocking sounds to be consistently synchronized with your engine’s speed, measured in revolutions per minute (rpm). For example, at 2,000 rpm (seen on your dashboard), you’d expect to hear a cycle of about 33 repetitive noises per second.
Warning Lights
Modern cars have highly advanced ECUs that can detect problems as they occur. You can expect to see many lights appear on the dashboard, warning you of the immediate crisis.
As it seems to be becoming common in driving culture in some places, don’t ignore dashboard warning lights! They could be the difference between a relatively low-cost fix and a dangerous car crash resulting in thousands of dollars in damages and write-offs.
In particular, the Check Engine and oil warning lights are likely to illuminate. When the ECU realizes there’s any problem with the engine, it switches the Check Engine light on. Likewise, blockages and breakages will impede the oil flow, causing this light to come on.
Complete Lack Of Performance
When an engine locks up, it essentially no longer works. Performance levels will drop significantly in the minutes or moments before seizing completely. Expect to feel poor acceleration, struggling at idle, stalling, trouble starting, and difficulty driving uphill.
Modern cars will default to Limp mode, also known as Limp Home mode. This shuts off every non-essential aspect of the car to protect itself, forcing you to drive exceptionally slowly to the nearest mechanic you can find.
When the engine does eventually seize, everything will stop dead.
What Causes An Engine To Lock Up?
The best way to keep your engine from seizing is through routine maintenance. This is often neglected by the average vehicle owner. Still, it’s a crucial aspect of looking after your car in the long term.
Most of the time, engines lock up because of excessive heat or physical damage to internal components. When the metal parts within the engine get too hot, they can expand and quite literally get physically stuck.
Sometimes they even affix themselves to the metal part they’re abrading against. Physical harm can also happen because of rust, contaminated oil, or significant amounts of dirt within the block.
You should always watch your temperature gauge. If it starts spiking, there’s most likely a problem with your coolant or oil system. Ensure both are filled to the correct level and allow the engine to cool before restarting it and seeing if the temperature’s back under control.
Make sure you regularly take your vehicle for oil and filter changes. Without the appropriate lubrication, everything goes wrong. Most seized engines occur because of neglecting this aspect.
Con rods, piston rings, bearings, and more can be physically harmed. If they break off, they’ll shoot around within the engine and cause even more destruction, eventually stopping it in its tracks.
As a final note, engine seizing can be just by a substantially out-of-sync timing belt or chain. If the timing is wrong, it’ll lead to knock, elevated temperatures, and low power. In interference engines, the valves could be destroyed by the pistons, leading to the same thing.
You might have also learned about a hydrolocked engine. This occurs when water enters the combustion chamber. It cannot be burned or compressed, causing harm to the metal pushing against it.
What Happens When An Engine Locks Up While Driving?
If the engine seizes while driving, it’ll most likely sound coarse for a short time before abruptly stopping. Without warning, everything will go quiet, although the electronics in your vehicle will probably still work.
It’s not like the movies. The car won’t suddenly do a forwards flip and land on its roof. Put the car in Neutral and carefully coast over to the shoulder, immediately putting your turn signals or hazard warning lights on.
Bear in mind that you’ll lose power braking, engine braking, and possibly power steering without the engine.
Therefore, it’ll take a lot more effort to bring the car to a halt, and the steering will feel much heavier than usual. Make sure nothing stops in front of you, as there will be little to no way of avoiding them.
The key is to stay calm and pull over, bringing the car gently to a halt as quickly as possible.
What Are The Signs Of A Seized Engine?
If you think your car’s engine has seized up, you’ll be unable to start it.
When you turn the key in the ignition, you’ll most likely hear a click and the sound of a motor attempting (but failing) to turn. This is the starter motor engaging its pinion with the flywheel. However, the flywheel won’t be able to spin, creating the dreadful sound you hear.
Don’t mix it up with the typical discharged battery symptoms, which can appear the same. If you have a locked engine, it will have halted very suddenly while running.
Motors can’t seize up while switched off unless they’ve picked up damage after standing for many years. If you saw no sign of a battery warning light, there’s another indication that the problem isn’t electrical.
When you take your vehicle to a reliable mechanic (it will need to be towed or carried on a flatbed), they’ll first check the electrical components and use an OBD II code reader to read the car’s logs on what happened.
They’ll then remove the engine and attempt to rotate it manually. If they can’t, it’s definitely seized.
Can You Fix A Seized Engine?
It might technically be possible to repair a locked-up engine, but you shouldn’t. For a start, it’ll be more costly than an engine replacement.
Secondly, it requires welding, and even expert welding isn’t as strong as cast metal.
Finally, a seized engine can do all sorts of damage throughout the block and beyond. If just one of these tiny cracks is missed, it could happen all over again.
Your ideal option is a replacement engine. This will cost thousands of dollars, but it’s realistically your only choice if you’re determined to keep your car.
Unfortunately, the best option for most individuals is to scrap the car and buy a fresh one.
