980 UK enquiries in 2025, typical failure mileage of 80,000–140,000 miles, and a crankshaft bearing failure that can be catastrophic – this is the real-world data behind the Land Rover 306DT TDV6/SDV6.
The 306DT (TDV6/SDV6) is the second most‑enquired Land Rover engine in our 2025 data with 980 enquiries [EM‑VERIFIED], typically failing between 80,000 and 140,000 miles. The primary failure is crankshaft bearing failure (tin‑aluminium coating fatigue), with a full reconditioned replacement costing £6,500–£9,500 [EM‑QUOTE]. On typical host vehicles (L405, L494, L319), replacement is financially ✅ Safe – the cost sits well within the vehicle's value.
Below we break down the failure rate context, mileage distribution, most common failure modes, and what it means for your ownership.
Where the 306DT sits relative to other Land Rover engines.
In 2025, the 306DT generated 980 enquiries [EM‑VERIFIED], making it the second most‑enquired Land Rover engine behind the 204DTD (1,150). It accounts for approximately 20% of all Land Rover engine enquiries – a significant share driven by its widespread fitment across the Range Rover Sport (L494), Range Rover (L405), Discovery 4 (L319), and later Discovery 5 models.
Importantly, enquiry volume does not equal failure rate [PATTERN DATA]. The 306DT is one of the most common engines in the Land Rover parc, which naturally elevates its absolute enquiry count. However, the catastrophic nature of its primary failure – crankshaft bearing failure – means it is a high‑stakes engine to own. When it fails, it often requires a full engine replacement rather than a repair.
Compared to other V6 diesels, the 306DT sits in the same failure mileage band as the older 276DT (2.7 TDV6), but with a higher enquiry volume. The 448DT (4.4 SDV8) is significantly more durable, with a typical failure mileage of 100k–200k miles, but it is a much rarer engine.
For the full comparison across all engines, see the Engine Failure Index 2026.
When does the 306DT typically fail?
Our data shows a typical failure window of 80,000–140,000 miles [PATTERN DATA]. This is derived from customer enquiry descriptions, supplier notes, and manufacturer TSBs. The distribution is not uniform – we see a cluster of failures occurring around the 100,000–120,000 mile mark, which is consistent with the crankshaft bearing fatigue mechanism.
Pre‑2012 models appear to have a slightly higher risk at the lower end of this range, while post‑2012 units may extend towards 140,000 miles with diligent servicing. However, the bearing failure is not mileage‑dependent alone – driving style, oil quality, and service history play significant roles.
Estimated distribution based on 306DT failure reports [ESTIMATED].
For a detailed breakdown of failure mileage across all engines, see the Average Mileage at Failure report.
What actually fails on the 306DT?
| Rank | Failure Mode | Typical Mileage | Typical Repair Cost | Severity |
|---|---|---|---|---|
| 1 | Crankshaft bearing failure (tin‑aluminium coating fatigue) | 80k–140k | Bottom‑end rebuild: £5,500–£7,000 Full reconditioned: £6,500–£9,500 | Catastrophic |
| 2 | Oil pump issues – loss of pressure, often secondary to bearing failure | 80k–140k | Oil pump: £1,000–£2,000 | Immediate |
| 3 | Turbocharger contamination – metal debris from bearing failure | 80k–140k | Turbo: £1,200–£2,500 | Immediate |
Data from Known Failure Patterns table [PATTERN DATA]. Costs [EM‑QUOTE].
The crankshaft bearing failure is the primary concern. It is often heralded by a cold‑start knock – if you hear this, it is an early warning sign. The bearing failure can be catastrophic, with the crankshaft seizing or the bearing shell spinning, causing extensive damage to the bottom end.
For a detailed guide on this specific failure, see our 306DT Crankshaft Bearing Failure page.
Lifespan is not fixed – it depends on maintenance and driving patterns.
With diligent maintenance (5,000‑mile oil intervals using the correct 5W‑30 or 5W‑40 spec, regular oil analysis from 80k miles), many 306DT engines exceed 150,000 miles without major failure. We have seen examples in our data reaching 180,000–200,000 miles on original bottom ends.
However, the typical failure window of 80k–140k miles reflects the reality for most owners. The key factors that push an engine towards the lower end of this range are:
For a broader view of Land Rover engine lifespan, see the Engine Lifespan Data report.
The answer depends on your ownership approach.
The 306DT is a high‑stakes engine. When maintained correctly, it can deliver 150,000+ miles of reliable service. But when it fails, the cost is high – a full reconditioned replacement is £6,500–£9,500, and a bottom‑end rebuild is £5,500–£7,000. The catastrophic nature of the crankshaft bearing failure means that once it starts knocking, the engine is often beyond economical repair.
We rate the 306DT as ⚠️ High Risk but Manageable. The risk is real, but it is well‑understood and can be mitigated with preventative measures. If you own one, 5,000‑mile oil changes and oil analysis from 80k miles are non‑negotiable. And never ignore a cold‑start knock – that is your early warning system.
On the repair‑to‑value front, the engine is ✅ Safe on typical host vehicles (L405, L494, L319), meaning replacement cost is well within the vehicle's value. This is why we see so many owners choosing to replace rather than scrap.
For a personalised recommendation based on your vehicle, use our Repair vs Replace Calculator.
Crankshaft bearing failure is the primary issue, typically occurring between 80,000 and 140,000 miles. It is caused by tin‑aluminium coating fatigue on the bearing surfaces.
With proper maintenance (5k oil intervals, correct oil spec), many last beyond 150,000 miles. The typical failure window is 80k–140k miles, but diligent owners can push to 180k+.
Both have similar failure windows (80k–140k), but the 306DT is more common in newer vehicles. The 276DT has a known oil pump failure point, while the 306DT's primary failure is the crankshaft bearing.
Yes – on typical host vehicles (L405, L494, L319), replacement is financially sound. The engine carries a ✅ Safe flag, meaning the cost is well within the vehicle's value.
980 Real EnquiriesThe 306DT‑specific dataset behind every figure on this page.
Limitations DisclosedEnquiry volume ≠ failure rate – we state this plainly.
Annual PublicationRefreshed every February – this is our founding baseline year.
100% IndependentNo sponsors, no manufacturer influence.
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