Cracked Cylinder Head

Cracked cylinder head: Causes, Symptoms, and What to do

A cracked cylinder head is much too frequently misdiagnosed as a blown head gasket by do-it-yourselfers and even some professionals. The error is simple to make because many of the symptoms of the two issues are similar.

Cracked Cylinder Head

You should take care of a broken cylinder head as soon as possible to prevent future harm to the car. Do you suspect that your car has a fractured head? Well, in this article, we’ll go deep into a cracked cylinder head, addressing the following questions:

  • What Is a Cylinder Head?
  • How Do Cylinder Heads Operate?
  • Why is the cylinder head cracked?
  • What are the symptoms of a cracked cylinder head?
  • How much does it cost to fix a cracked cylinder head?

Ok, let’s get started!


What Is a Cylinder Head?

A cylinder head sits atop an engine block and covers its cylinders, creating the combustion chamber. The cylinder head, which is held in place by the head gasket, makes room for the tubes that provide fuel and air to the cylinders.

The head must be strong enough to withstand the stresses placed on it without cracking or fracturing due to the high pressure and frequently fluctuating temperatures. It is a complex and essential component of the engine and the car as a whole, therefore any issue that can arise needs to be fixed as soon as feasible.

How Does the Cylinder Head Operate?

The cylinder head connects to the intake and exhaust manifolds to enable the fast combustion of fuel and air that propels the engine’s pistons, allowing the engine to operate at optimal efficiency. Air is introduced into the head through the intake manifold, where it is combined with gasoline and burned to create exhaust gases that are released through the exhaust manifold. To keep the engine operating smoothly, it’s critical that the intake and exhaust valves, which let the admission and escape of pertinent gases, open and close at the proper periods.

Why is the cylinder head cracked?

Some cylinder heads, like those on a Saturn engine, are susceptible to cracking as a result of design defects. But engine overheating is typically the cause of the issue. Thermal stress causes the cylinder head to shatter when an engine runs too hot. Even one instance of engine overheating might lead to a broken cylinder head.

The most frequent cause of cylinder head failure is overheating, which can be brought on by coolant loss, head gasket failure, or restricted coolant flow, among other things. In extreme circumstances, a cracked or broken cylinder head might cause total engine destruction! To try to stop this from happening, you must address any issues as soon as you can.

Furthermore, cylinder heads are subject to great pressure from abrupt temperature changes, which can cause them to deform. This indicates that it no longer provides a flat surface to maintain the head gasket in the proper position, which can cause costly issues down the road that require significant repairs or engine replacement in its entirety.

A particular issue with aluminium cylinder heads is warping. Different engines have varying amounts of cylinder head warping tolerance; some may endure significant warping while still performing well. If your cylinder head does warp, you might be able to take it to a mechanic who has experience realigning them; if not, you’ll probably need to get a new one.

What are the symptoms of a cracked cylinder head?

There are one or more-cylinder heads on every engine. Two-cylinder heads are present in engines with a “V” or flat configuration, whereas one is present in engines with an inline or straight configuration. The tops of the cylinders inside the engine block are sealed by the cylinder head.

Additionally, the engine’s head houses the valves (and occasionally the camshafts) that permit the entry of the air/fuel mixture and the escape of exhaust gases. An engine head gasket serves as a seal between the cylinder head and engine block.

The signs of a blown head gasket are frequently shared by those of a cracked cylinder head. Therefore, before reinstallation whenever you (or your mechanic) replace a head gasket, the heads should be examined by a machine shop for cracks.

Specialized tools and technology used in machine shops can find cylinder head cracks that are invisible to the naked eye. You may experience one or more of the following signs if your car does really have a damaged cylinder head:

  • Overheated engine.
  • Low Level of Coolant.
  • Exhaust Pipe Steaming White Smoke.
  • Water Pump Failure
  • Faulty thermostat
  • Coolant Leak
  • Misfiring and Uneven Running.
  • Oil-Coolant Intermix.
  • Warning Lights On.
  • Combustion Gases in the Cooling System.

Overheated engine

Coolant may enter the combustion chamber through a cracked cylinder head instead of flowing through the engine as intended. As a result, the engine can begin to overheat.

Low Level of Coolant

You might observe that the coolant level starts to decline if the cylinder head crack allows coolant to enter (and be burned) inside the combustion chamber.

Exhaust Pipe Steaming White Smoke

The cylinder head has coolant tubes that go through it. A head crack can let coolant from those tubes leak into the engine’s combustion chamber, where it burns when the engine is burning. As a result, the vehicle’s exhaust will emit what appears to be white smoke but is actually steam. The lovely fragrance of the exhaust fumes may also catch your attention.

Water Pump Failure

If the water pump breaks down, the coolant will not be able to circulate properly in the engine. Even though it may be nice and chilly in the radiator, the coolant around the water jackets in the head and block will be very hot. Coolant can only move through natural convection in the absence of a pump, and this process moves far too slowly to remove more heat before the engine overheats. If you are unsure of the date that your car’s water pump was last serviced, look online for Reading garages and make a water pump replacement appointment as soon as you can.

Faulty thermostat

At the operating temperature for which they were designed, combustion engines perform at their peak efficiency. Engines typically operate between 190- and 210-degrees Fahrenheit, or 85 and 99 degrees Celsius, which is hot enough to scald you. The fuel consumption, emissions, and wear of an engine increase when its operating temperature is lowered.

To find out if a prior MOT test failed due to excessive emissions, use an online MOT history checker. A thermostat stops coolant from evaporating from the radiator until the engine coolant reaches the appropriate temperature. Once the engine reaches the desired temperature, the thermostat opens, letting coolant at room temperature cool it down until the thermostat gets cold enough to close.

The cycle continues as the engine runs. If the thermostat is stuck open, your car will probably run extremely cold. This is because the radiator never has a chance to fully warm up because it receives a steady flow of coolant from the entire system. If the thermostat is jammed closed, your engine will overheat rather quickly.

The hot coolant has nowhere to go to cool off. On some engines, the heater can be briefly used as a small radiator. The efficiency of this technology is influenced by the size of the heater core and the placement of the cooling system.

Coolant Leak

If too much coolant seeps out over time, you won’t have enough to keep the engine cool enough. However, it’s a good idea to regularly check the radiator and overflow reservoir to make sure you have enough coolant because you can lose a significant amount of liquid before overheating.

If you think there might be a coolant leak, checking your radiator cap is a great idea. It’s a cheap part, but if it malfunctions, it might have serious implications. Keep in mind that not all coolant leaks are visible. Small cylinder head cracks can occasionally go unnoticed for a while, but in more severe cases, the symptoms will be quite obvious.

Misfiring and Uneven Running

Three factors are required for a full-combustion engine: a good spark, the right air/fuel ratio, and sufficient compression. Loss of compression from a broken cylinder head can make the engine run rough and misfire.

Oil-Coolant Intermix

Coolant and oil may occasionally mix as a result of a broken cylinder head. Some 1.9L single overhead camshaft Saturn vehicles are notorious for developing damaged cylinder heads, which results in coolant-oil mixing.

Warning Lights On

The check engine light, low coolant level light, and engine over-temperature light can all be set off by a broken cylinder head. You might also notice it starts to rise if your automobile has a temperature gauge.

Combustion Gases in the Cooling System

The cooling system may become contaminated by combustion gases due to a broken cylinder head. As a result, the coolant may have an excessive number of bubbles before it starts to boil. You might also notice that there is a lot of pressure on the cooling system.

How much does it cost to fix a cracked cylinder head?

Cylinder head repairs are typically a thing of the past. Nowadays, almost all shops will replace a cracked head rather than attempt a repair because the majority of new heads are constructed of aluminum. You should typically budget between $1000 and $2,500 per cylinder head if you decide to have a professional replace them in your car.

The precise cost will, of course, vary depending on a number of variables, including the year, make, and model of your car. It’s also important to bear in mind that occasionally, extra damage to other engine components results from a cracked cylinder head. You’ll most likely need to repair or replace the engine entirely in this situation.

Related Article

Are you a mechanically inclined DIYer? Then this video will really help you to fix a cracked cylinder head:

FAQs about cracked cylinder head

Can you drive with a cracked cylinder head?

It’s crucial to know that driving with a cracked engine part is no different from driving with any other problem. If you continue to drive without fixing the issue, it will eventually get worse.

Is a cracked cylinder head repairable?

There is always a risk involved in repairing a broken cylinder head, but when done correctly, it is typically significantly less expensive than replacing the head with a new or used casting. The majority of tiny cast iron and aluminum head cracks can be fixed by pinning.

What happens if cylinder head cracks?

In extreme circumstances, a cracked or broken cylinder head might cause total engine destruction! To try to stop this from happening, you must address any issues as soon as you can. Furthermore, cylinder heads are subject to great pressure from abrupt temperature changes, which can cause them to deform.

How much does it cost to fix a cracked cylinder head?

You will undoubtedly pay at least $500 for it, which also includes the cost of the labor and the parts. The cost of the parts to replace the complete head ranges from $200 to $300 on average. The cost of labor will be $100 per hour.

How long will an engine last with a cracked head?

An automobile with a blown head gasket typically doesn’t last more than a month, depending on how bad the leak or hole is.

Is it worth replacing a cylinder head?

If the engine is still running at all, failing to repair a fractured cylinder head could result in additional engine damage. This can necessitate even more costly repairs, such as an engine replacement. Your automobile might not even be drivable if your cylinder head is damaged.

What causes the head gasket to fail?

The most common cause of head gasket failures is engine overheating, therefore make sure the coolant level is maintained and that the cooling system is functioning properly with no leaks and an effective radiator. Future harm can be avoided with a head gasket that is placed correctly.

Does a blown head gasket mean I need a new engine?

Further issues with other engine components or permanent harm to the engine could have resulted from the blown head gasket. A full engine may need to be installed or a new vehicle may need to be purchased if the burst head gasket has resulted in catastrophic damage.

Can you JB Weld a cracked cylinder head?

Some automotive aphorisms are tossed around like hot dogs at a picnic when you’re really craving a cheeseburger.


Different cylinder head failure signs exist, thus it’s critical for drivers to be able to identify them as soon as possible in order to limit damage. The engine (and ultimately the car) will fail if the cylinder head malfunctions. That is all for this article. Hope it was an informative one. If so, kindly share it with others. Thanks for reading; see you around!


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