Land Rover 306DT Cylinder Head Failure: Symptoms, Causes & Replacement Guide

The Land Rover 306DT engine (also known as the 3.0 TDV6 or SDV6) has been a popular powertrain in models like the Discovery 4, Range Rover Sport, and Range Rover Velar.

While this 3.0-liter V6 diesel engine offers strong torque and decent efficiency, one of the more serious and costly issues owners may face is cylinder head failure.

In this guide, we will explain the common symptoms of a failing Land Rover 306DT cylinder head, the main causes behind the problem, how to confirm the issue,

and what you should know before replacing the cylinder head.

What is the Land Rover 306DT Engine?

The 306DT is a 3.0-liter V6 turbocharged diesel engine developed under the Ford-PSA Lion engine family. It features:

• Aluminum cylinder heads

• Cast-iron cylinder block

• 24-valve DOHC design

• Single or twin-turbo setup (depending on power version)

• Common rail direct injection

It was widely used in Land Rover vehicles from around 2009 to the late 2010s. Because the cylinder heads are made of aluminum, they are lighter but more sensitive to overheating and improper maintenance compared to older cast-iron designs.

Common Symptoms of 306DT Cylinder Head Problems

If your Land Rover 306DT engine is developing cylinder head issues, you may notice one or more of the following symptoms:

• Persistent coolant loss with no visible external leak

• White smoke from the exhaust (especially on cold start)

• Engine overheating

• Milky or discolored engine oil (coolant mixing with oil)

• Rough idle or misfires

• Loss of power

• Sweet smell from the exhaust

• Bubbles in the coolant reservoir

These symptoms often point to a cracked cylinder head, a failed head gasket, or warping of the cylinder head sealing surface.

Main Causes of 306DT Cylinder Head Failure

Several factors can lead to cylinder head problems on the 306DT engine:

1. Overheating – The most common cause. Restricted radiators, failing water pumps, or low coolant levels can quickly damage aluminum heads.

2. Head gasket failure – Once the gasket fails, combustion gases and coolant can mix, accelerating head damage.

3. Age and high mileage – Thermal cycling over many years can cause the aluminum head to crack or warp.

4. Poor maintenance – Infrequent coolant changes or using the wrong coolant type increases corrosion risk.

5. Tuning and higher boost – Modified engines running higher boost pressures put extra stress on the cylinder heads.

How to Confirm Cylinder Head Damage

Before replacing a cylinder head, proper diagnosis is essential:

• Perform a compression test and cylinder leak-down test

• Check for combustion gases in the cooling system (block test)

• Inspect the oil for coolant contamination

• Remove the cylinder head for visual inspection and pressure testing

• Check the head surface for flatness (warpage)

A professional machine shop can pressure-test the head and measure flatness to determine whether it can be resurfaced or must be replaced.

306DT Cylinder Head Replacement Tips

Replacing a cylinder head on the 306DT is a major job. Keep these points in mind:

• Always replace both the head gasket and head bolts (torque-to-yield bolts should not be reused)

• Check the cylinder block surface for flatness as well

• Use the correct coolant and bleed the cooling system thoroughly after installation

• Confirm whether you need the left-hand (LH) or right-hand (RH) cylinder head

• Match the correct OE number to your vehicle’s engine code and model year

Common OE Numbers for 306DT Cylinder Heads

Here are some frequently referenced OE numbers for the Land Rover 306DT cylinder head:

• LR013083 / LR013084

• LR014248 / LR014249

• LR041630 / LR041631

• 9X2Q-6C032-BA / 9X2Q6C032BA

• PM9X2Q6C064DA

Always verify the exact part number using your VIN, as there can be differences between early and later versions of the 306DT engine.

Buying Advice: What to Look For

When purchasing a replacement 306DT cylinder head, consider the following:

• Prefer heads that have been pressure-tested

• Confirm it is suitable for your specific power version (TDV6 or SDV6)

• Decide between a bare cylinder head or a complete head with valves and springs

• Choose a reputable supplier that provides clear OE number matching and after-sales support

Conclusion

The Land Rover 306DT engine is generally robust, but aluminum cylinder heads can fail if the engine overheats or is poorly maintained. Recognizing the early symptoms and addressing cooling system issues promptly can help prevent expensive repairs.

If you do need a replacement, using the correct OE number and a quality cylinder head is critical for long-term reliability. Always diagnose the root cause—especially overheating—before fitting a new head.

FAQ

Q: Can a cracked 306DT cylinder head be repaired?
A: Minor issues can sometimes be repaired by a specialist, but cracking in critical areas usually requires full replacement.

Q: How much does it cost to replace a 306DT cylinder head?
A: Costs vary widely depending on labor rates, whether one or both heads are replaced, and parts quality. It is generally a high-cost repair.

Q: Is the 306DT cylinder head the same on Discovery 4 and Range Rover Sport?
A: In most cases the heads are interchangeable, but you should always confirm with the OE number and VIN.