Remanufactured Cylinder Heads: A Smart Choice?

A cylinder head is a critical component of your engine, sitting atop the cylinder block and sealing the combustion chambers where the magic of converting fuel into power happens. When this vital part cracks, it can lead to significant issues and hefty repair bills. While purchasing a brand-new cylinder head is often considered the most straightforward solution, the world of automotive repair also offers remanufactured cylinder heads. But should you buy one? Let's delve into the reasons why cylinder heads crack, the tell-tale signs, and the pros and cons of opting for a remanufactured unit.

What Causes a Cylinder Head to Crack?

Understanding the root causes of a cracked cylinder head is the first step in appreciating why a repair or replacement might be necessary. The high-pressure, high-temperature environment within an engine puts immense stress on this component. Here are the most common culprits:

1. Overheating

This is arguably the most significant contributor to cylinder head failure. Internal combustion engines generate a tremendous amount of heat. While designed to manage this, extreme temperatures can push the material beyond its limits. Most modern cylinder heads are made from aluminium, a lightweight and efficient material, but it can warp or crack when subjected to excessive heat. Overheating often stems from a malfunctioning cooling system. A compromised cooling system, whether due to a leak, a faulty water pump, or air pockets, can prevent the engine from dissipating heat effectively, leading to thermal stress on the cylinder head.

2. Air in the Cooling System

Air pockets within the cooling system are a silent menace. Unlike coolant, air is a poor conductor of heat. This means that even if the coolant temperature sensor reads a normal temperature, localised 'hot spots' can form within the engine block and cylinder head. If these hot spots occur in areas not adequately monitored by the sensor, the engine can overheat without the driver being immediately aware. Furthermore, air in the system can reduce the overall pressure, potentially lowering the boiling point of the coolant, making it more susceptible to boiling and causing further damage.

3. Failed Water Pump

The water pump is the heart of the cooling system, circulating coolant throughout the engine. If the water pump fails, coolant can no longer circulate efficiently. While the radiator might contain cool coolant, the coolant within the engine block and cylinder head can become dangerously hot. Without the pump's assistance, coolant can only rely on natural convection for circulation, which is far too slow to remove excess heat effectively. This rapid build-up of heat is a direct path to a cracked cylinder head.

4. Failed Thermostat

The thermostat acts as a gatekeeper for the cooling system. It remains closed until the engine reaches its optimal operating temperature (typically between 190-210°F or 88-99°C). Once this temperature is reached, it opens, allowing coolant to flow to the radiator for cooling. If the thermostat gets stuck in the open position, the coolant will constantly circulate through the radiator, preventing the engine from reaching its ideal operating temperature. While this might seem preferable to overheating, running too cold can lead to increased wear, poor fuel economy, and higher emissions, and in some cases, can still contribute to cylinder head issues. Conversely, if the thermostat is stuck closed, coolant cannot reach the radiator, leading to rapid and severe overheating, a direct cause of cylinder head cracking.

5. Coolant Leak

An obvious coolant leak means there isn't enough coolant circulating to keep the engine cool. Even before the engine starts to overheat, a significant amount of coolant can be lost. Regularly checking your coolant reservoir and radiator levels is crucial. Leaks can be caused by various factors, including a faulty radiator cap, which can't maintain the correct system pressure. It's also important to remember that not all coolant leaks are visible; some can be internal.

Symptoms of a Cracked Cylinder Head

A cracked cylinder head can manifest in several ways, ranging from subtle to glaringly obvious. Here are the most common symptoms to look out for:

1. Oil Leak

The cylinder head houses oil passages. A crack can allow oil to escape, potentially leading to a low oil pressure warning light on your dashboard. Inspecting around the cylinder head for signs of oil seepage is essential. Sometimes, the leak can be internal, meaning oil might enter the combustion chamber, resulting in blue smoke from the exhaust pipe, rather than an external puddle.

2. Coolant Leak

While a coolant leak can cause a crack, it can also be a symptom of one. In more severe cases, coolant might leak externally, often mixing with oil. This will invariably lead to the engine overheating, indicated by the temperature gauge. Internal coolant leaks are more insidious; coolant can seep into the combustion chamber or oil passages. If you notice your coolant level dropping rapidly, do not drive the vehicle. This is a strong indicator that a cylinder head repair is imminent.

3. Poor Engine Performance

A cracked cylinder head can compromise the seal within the combustion chamber. This means that the compressed air-fuel mixture can escape, leading to a noticeable loss of engine power. The engine may feel sluggish or struggle to accelerate.

4. Smoke from Engine

While less common, a cracked cylinder head can cause coolant to leak into the combustion chamber, where it is burned along with the fuel, producing white smoke from the exhaust. Similarly, if engine oil leaks into the combustion chamber or comes into contact with hot engine components, it can also produce smoke, which might be blue or black.

5. Engine Misfire

Related to poor engine performance, a crack in the cylinder head can disrupt the proper combustion process. If the air-fuel mixture is compromised, it may not ignite correctly, leading to an engine misfire. You might experience rough idling, hesitation, or the engine cutting out entirely, requiring repeated attempts to restart.

Cylinder Head Repair vs. Replacement Costs

The cost associated with addressing a cracked cylinder head can vary significantly depending on the vehicle's make and model, the material of the cylinder head (aluminium or iron), and the labour rates in your area. Generally, expect a minimum of £400 for a repair, which includes parts and labour. If a full replacement is necessary, the cost for parts alone can range from £150 to £250 for an aluminium head. Labour costs can add another £100 per hour, potentially bringing the total for replacing an aluminium head to around £500 or more. More complex engine designs or those with iron heads (often found in older or more robust vehicles) can increase both parts and labour costs, potentially reaching £800 or higher.

Should You Buy a Remanufactured Cylinder Head?

This is where the decision-making process truly begins. Given the costs of repair and new parts, a remanufactured cylinder head often presents an attractive alternative.

What is a Remanufactured Cylinder Head?

A remanufactured cylinder head is a used cylinder head that has been disassembled, thoroughly cleaned, inspected for wear and damage, and then rebuilt to meet or exceed original equipment (OE) specifications. This process typically involves:

• Disassembly and Cleaning: The head is taken apart, and all components are meticulously cleaned to remove carbon deposits, oil, and debris.
• Inspection: Using specialized tools and techniques, the head is inspected for cracks, warping, porosity, and wear on critical surfaces like valve seats and guides.
• Machining: If necessary, surfaces are machined flat to ensure a perfect seal. Valve seats and guides are often replaced or reconditioned.
• Replacement of Worn Parts: Gaskets, seals, and sometimes valves are replaced with new components.
• Assembly: The head is reassembled with new and reconditioned parts.
• Testing: The remanufactured head is often pressure tested to ensure it holds integrity.

Pros of Remanufactured Cylinder Heads:

• Cost-Effective: Significantly cheaper than a brand-new OE cylinder head, often offering savings of 30-50%.
• Environmentally Friendly: Reusing components reduces waste and the need for raw materials.
• Quality Assurance: Reputable remanufacturers adhere to strict quality control processes, ensuring the head performs like new. Many come with a warranty.
• Reduced Downtime: Often readily available, potentially reducing the time your vehicle is off the road compared to waiting for a new part or extensive repairs.

Cons of Remanufactured Cylinder Heads:

• Potential for Hidden Issues: While reputable companies have rigorous checks, there's always a slight risk of an undetected flaw in a used core.
• Variability in Quality: The quality of remanufacturing can vary between suppliers. It's crucial to choose a trusted provider.
• Warranty Concerns: Ensure the warranty offered is comprehensive and covers both parts and labour, should an issue arise.

Making the Decision

The decision to buy a remanufactured cylinder head hinges on a few key factors:

1. Your Mechanic's Recommendation: Always consult with a trusted mechanic. They can diagnose the problem accurately and advise on the best course of action.

2. Supplier Reputation: If opting for remanufactured, research suppliers thoroughly. Look for companies with positive reviews, clear quality control processes, and solid warranties.

3. Cost vs. Risk: Weigh the cost savings against the potential, albeit small, risk of a remanufactured part. For many, the savings are well worth it when sourced from a reputable provider.

4. Vehicle Age and Value: For older vehicles, a remanufactured part can be a more practical and economical choice than an expensive new OE component.

Table: New vs. Remanufactured Cylinder Head

Frequently Asked Questions

Q1: Is a remanufactured cylinder head as good as a new one?

A1: When remanufactured by a reputable company with strict quality control, a remanufactured cylinder head can be just as reliable as a new one. They are rebuilt to meet original specifications.

Q2: How long does a remanufactured cylinder head typically last?

A2: With proper installation and maintenance, a well-remanufactured cylinder head can last for the lifetime of the vehicle, similar to a new one.

Q3: What is the difference between a remanufactured and a rebuilt cylinder head?

A3: While often used interchangeably, 'remanufactured' generally implies a more thorough process, including disassembly, cleaning, inspection, repair, and replacement of worn parts to meet OE standards. 'Rebuilt' can sometimes be a less comprehensive process.

Q4: Can I install a remanufactured cylinder head myself?

A4: Cylinder head replacement is a complex task requiring specialized tools and knowledge. It's highly recommended to have it performed by a qualified mechanic to ensure correct installation and prevent further damage.

In conclusion, a cracked cylinder head is a serious issue that requires prompt attention. While a new cylinder head is the premium option, a remanufactured cylinder head from a trusted supplier can offer a cost-effective, reliable, and environmentally conscious solution for getting your vehicle back on the road.