What causes a seized engine? This is the first question that will come to mind if you encounter this serious car problem.
Knowing the possible reasons is crucial, mainly for avoiding the same problem from happening again and losing even more time and money.
Another good thing when you know the reason is that sometimes you don’t have to make a big repair. In these cases, you might be able to start the engine again without causing any damage.
Hopefully, this article will provide you with some insight on the matter and give a few guidelines on why the engine seized in the first place.
WHAT IS A SEIZED ENGINE?
Before we start, just a few words what a seized engine actually means.
The basic definition would be: a seized engine is one where there is no turnover.
No turnover means that all of the key engine parts that rotate and move (like the crankshaft, pistons, connecting rods, etc) get stuck.
A seized engine is immediately noticed in two ways:
- The pulleys can’t be turned by hand. They will seem like welded into place.
- When you try to crank the engine you’ll hear just a click sound, much like when the starter is faulty. This is the starter trying to turn over the engine but it can’t because it’s seized.
WHAT CAUSES A SEIZED ENGINE? 10 COMMON REASONS
1. LACK OF ENGINE OIL
The first thing you should do when wanting to find out what causes a seized engine is to check the engine oil level.
Pull out the dipstick and check the level. If it’s between minimum and maximum, that’s OK and this isn’t the problem.
Even if it’s’ on the minimum and the engine is in good condition, it shouldn’t seize because of this.
But if it’s bone dry, then this might easily be the problem.
You see, the proper functioning of an inner combustion engine is impossible without engine oil. Without it, the friction and heat would destroy it in a matter of minutes.
Some common reasons for a lack of engine oil are:
Lack of maintenance and regular checkups
Checking the oil is something a driver should do on a regular basis. If the level goes under the minimum and stays that way for a while, it can easily cause the engine to seize.
Besides checking the oil, a crucial factor is changing it on time.
If not, the oil loses its viscosity and lubrication properties which can also lead to engine damage.
The engine is burning oil
This usually happens on cars with higher mileage or on poorly maintained cars. It can also happen if the oil hasn’t been changed on time.
When the car burns engine oil, it has to be frequently added. Otherwise, the level will go low and may cause the engine to seize.
Some common reasons are faulty gaskets, faulty seals, damaged oil lines, or else. Material fatigue is among the main causes.
This problem is best noticed by oil stains under the car or a greasy engine.
Again, when oil is leaking, the level goes down and if unchecked, can cause a seized engine.
2. BAD OIL CIRCULATION
Besides the proper level, oil circulation is a key factor.
If oil doesn’t reach all the vital engine parts, it will suffer damage.
The most common reasons what causes a seized engine regarding oil circulation are:
Clogged or dirty oil filter
All of the engine oil goes through the filter cleansing it from any filth and debris that may appear.
When clogged, it stops the oil circulation which can cause a seized engine.
The most common reason for causing a clog is not changing it on time.
On this part, I would like to say that some drivers have the bad habit of changing only the engine oil but not the oil filter, mostly because of saving money.
Avoid this as the oil filter doesn’t cost much but is vital to the engine.
Faulty oil pump
The oil pump is in charge of providing oil pressure and without it, the oil wouldn’t be able to reach all parts of the engine.
If it’s faulty and the pressure is low, there’s isn’t proper lubrication and the engine will eventually seize.
Oil pumps are pretty long-lasting. Problems are mainly caused by material fatigue and not changing the oil on time.
Clogs within the system
This is a pretty rare fault that causes bad oil circulation. It happens mostly in higher mileage engines or ones with poor maintenance.
Filth and debris can build up inside the oil lines and canals in the engine block and weaken or even completely stop the oil flow around the engine.
One more reason may be some sort of previous unprofessional intervention on the engine.
3. QUALITY OF ENGINE OIL
Besides checking the oil level, see what engine oil was previously used.
The engine must have oil with the proper characteristics. Otherwise, there might be increased friction and heating, especially under higher strain.
Modern engines are especially sensitive to this. Almost every car manufacturer has the recommended engine oil (in terms of viscosity and who produces it) for a certain type of engine.
Besides friction and heating, low-quality oil can even lead to the engine burning oil or it evaporating from the system.
So apart from checking the level and the maintenance interval, make sure the proper oil was used. Preferably one that was recommended by the car manufacturer.
4. MECHANICAL FAILURE
When all the previous factors regarding the oil are OK, maybe it’s time to consider a mechanical failure within the engine.
Especially consider this if you’ve previously heard knocking or clunking sounds coming from the engine.
These noises may be caused by worn-out or faulty piston rings, connecting rods, crankshaft bearings, and else.
If this is the case, then a partial or complete engine rebuild is at hand.
A better but more rare option that causes similar sounds are things like a stuck or faulty pulley for instance.
For more reasons that may cause a knocking engine, click here for an article on that topic.
5. THE CAR HAS LAID IDLE FOR A LONG TIME
For cars that haven’t been driven for a long time and the engine hasn’t been started, it’s pretty easy to conclude what causes a seized engine.
Over time, the oil completely goes into the oil sump leaving all the vital engine parts dry.
After that, a thin rust build-up starts to form within the engine. The most problematic place is between the piston rings and the cylinder walls. Over time it sort of „welds“ them together.
When you try to crank the engine, you just get a click sound from the starter.
If you have a situation like this, best try manually turning over the engine before starting it to avoid causing damage.
6. HYDRO LOCK
One more rare reason but certainly worth considering if you’ve driven through some high water, like during a flood for instance.
The main danger here is that water, instead of air, gets into the air intake and then into the combustion chamber.
Once it gets there, it can easily cause huge damage like twisting the connecting rods, breaking the pistons, valves, and else.
This will then lead to a seized engine.
For a more in-depth explanation about the hydro lock topic, from Wikipedia, click here.
7. OVERHEATED ENGINE
If you’ve had problems with an overheating engine in the recent past, this is what easily may have caused the problem.
When the engine overheats, all of the crucial engine parts expand and cause a lot more friction and heat than normal. If it happened a couple of times, it may have caused the problem.
There are a number of reasons for an overheating engine. If you’re interested to see them, click here for a separate article on that topic.
8. BROKEN TIMING BELT OR TIMING CHAIN
One more thing you should check is when the timing belt or timing chain was last replaced.
When the belt or chain breaks, it can cause havoc inside the engine.
The piston collides with the valves and both are damaged or even broken making the engine completely seize.
Some engines are protected through engineering (the piston can’t reach the valve) but some are vulnerable.
Timing belts are more sensitive to this fault than timing chains. But they too break if not replaced on time.
9. BAD STARTER
Now, this is not a real reason for a seized engine but it can cause confusion and mislead you to think you have one.
When the starter is faulty, it produces the same click sound as when the engine is seized and when it can’t crank it.
So, before concluding what causes a seized engine, make sure that the battery and starter are in good condition.
If you want to see some common reasons for starter problems, click here for a separate article on that topic.
10. BAD DRIVING HABITS
This reason may seem out of place here, but frequently pushing your car’s engine to the limits may easily cause this kind of problem.
Especially if the car is older and isn’t in prime condition.
For instance, constantly driving in high revs will seriously increase the possibility of a problem. If you combine other factors like lack of oil, poor maintenance, engine overheating, and else you have a recipe for disaster.
If you want to see what are some of the worst driving habits, click here for another article on that topic.
As you’ve seen through this article, there are various reasons of what causes a seized engine.
But most of these reasons have one thing in common: you can successfully avoid them through proper maintenace as well as keeping a vigilant eye on your car’s condition.
Believe me, lots of these problems can be avoided if you do regular checkups and respect service intervals.
Checkups enable you to notice the problem on time which is a crucial factor in preventing this from happening.
Proper service intervals, besides increasing the longevity of your car, give you an insight into the car’s overall condition.
In the long run, all of these cost a lot less money, time, and nerves than facing the problem of a seized engine.
Written by: Sibin Spasojevic
Former car technician, life-long car and DIY enthusiast, author for Despairrepair.com