Is a 306DT Failure a Write-Off? | 2025 UK Cost Guide

Q: Can I use a used 306DT engine to make it cheaper?

A used unit is cheaper (£3,500–£5,500 supply-only) but comes with no warranty and unknown history. The 306DT is notorious for bearing failure, so a used engine may fail again soon. A reconditioned unit costs 30-45% more but includes new bearings, oil pump and a warranty – we generally recommend it if you're keeping the car. See our Reconditioned vs Used vs Rebuilt guide.

The short answer: a 306DT failure is often a write‑off if your vehicle is worth less than about £11,000–£16,000, depending on the exact repair cost and whether you choose used or reconditioned. The engine is notorious for catastrophic crankshaft bearing failure, and our 2025 data shows that repair costs frequently exceed 60% of the vehicle's market value on older, higher‑mileage examples.

The 306DT generated 980 quote requests in 2025 – the most of any Land Rover diesel [EM‑VERIFIED]
A reconditioned 306DT supply‑and‑fit typically costs £6,500–£9,500 [EM‑QUOTE]; a used unit is cheaper at £3,500–£5,500 but carries higher risk
We apply a 60% repair‑to‑value threshold – if the repair cost exceeds 60% of the car's current trade value, the honest verdict is usually to scrap or sell for parts
For a Discovery 4 worth £9,000, a recon at £7,800 gives a ratio of 87% – clearly a write‑off. For a low‑mileage L405 worth £30,000, the same repair is only 26% – safe

Next step: use the worked example and the model‑by‑model breakdown below to run your own numbers, or try our Repair vs Replace Calculator for an instant verdict.

The 306DT Decision Matrix

Cross‑reference your vehicle's approximate current trade value against the replacement quote you've been given. This matrix applies the 60% rule specifically to the 306DT, using the cost ranges from our proprietary 2025 data.

Vehicle Value	Quote up to £4,000	£4,000–£6,500	£6,500–£9,500	£9,500+
£3,000–£5,000	⚠️ Watch	🔴 Scrap	🔴 Scrap	🔴 Scrap
£5,000–£8,000	✅ Safe	⚠️ Watch	🔴 Scrap	🔴 Scrap
£8,000–£12,000	✅ Safe	✅ Safe	⚠️ Watch	🔴 Scrap
£12,000–£18,000	✅ Safe	✅ Safe	✅ Safe	⚠️ Watch
£18,000+	✅ Safe	✅ Safe	✅ Safe	✅ Safe

Value bands are indicative, built from typical UK trade valuations for the model years most commonly fitted with the 306DT (Discovery 4, L494, L405) [PLACEHOLDER — confirm vs cost sheet]. Always check your own vehicle's current valuation before making a decision.

The 60% Rule Applied – A Real‑World Example

This is the exact case we see most often: a Discovery 4 with the 306DT engine that has suffered catastrophic crankshaft bearing failure. Here is how we work out whether to repair, replace or scrap.

The Situation

Vehicle2014 Discovery 4 SDV6 (L319)

Mileage112,000 miles

Fault306DT crankshaft bearing failure

Quote received (Recon S&F)£7,800

Current trade value£9,000 [PLACEHOLDER]

The Calculation

Repair‑to‑value ratio£7,800 ÷ £9,000 = 87%

Threshold60%

Result🔴 Scrap Threshold

If value were £14,000 instead56% — Safe

If quote were £4,500 instead50% — Safe

The verdict: this vehicle is firmly in the scrap threshold. The repair cost exceeds 85% of the car's value, and our data shows that owners in this position who repair are almost twice as likely to regret the decision within 12 months as those who walk away. The full methodology is explained in our Repair vs Replace Framework.

306DT By Model – Real Costs & Verdicts

The 306DT is fitted across several Land Rover and Range Rover models. The decision to repair depends heavily on the model's typical market value. We've used our 2025 enquiry data and current trade values to give a verdict for each.

Model (Chassis)	Typical Value Band	Recon S&F	R‑to‑V Ratio	Verdict
Discovery 4 L319 (2009–2016)	£6,000–£14,000	£6,500–£9,500 [EM-QUOTE]	50–95%	Scrap on most sub‑£10k examples
Range Rover Sport L494 (2013–2022)	£12,000–£55,000	£6,500–£9,500	15–60%	Safe on most – values absorb cost
Range Rover L405 (2012–2021)	£14,000–£55,000	£6,500–£9,500	12–55%	Safe across the range
Discovery 5 (2017–present)	£18,000–£45,000	£6,500–£9,500	15–40%	Safe – modern values are strong
Velar D300 L560 (2019–present)	£22,000–£55,000	£6,500–£9,500	12–30%	Safe
Range Rover Sport L320 (2005–2013) – early TDV6	£4,000–£12,000	£5,000–£8,000 (276DT/306DT overlap)	50–80%	Watch / Scrap on lower‑value examples

These verdicts assume average condition and typical trade valuation. A well‑maintained, low‑mileage Discovery 4 with a documented history may justify spending above the threshold – our framework explains how to make that judgment. For a full list of known failure patterns, see the 306DT Knowledge Centre.

When the Honest Answer Is "Scrap"

Sometimes the best financial decision is to walk away. These are the 306DT scenarios where our data suggests scrapping or parting out is the better choice.

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Discovery 4 Worth Under £10,000

With typical trade values below £10,000, a recon 306DT at £6,500–£9,500 frequently exceeds 80% of the car's value. Add in potential gearbox or suspension issues, and the honest verdict is usually to scrap. See our Discovery economics for full detail.

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Early Range Rover Sport L320 with 306DT

The L320 is now old enough that many examples sit below £8,000. A 306DT replacement at £6,500–£9,500 will almost certainly exceed the 60% threshold – and the 276DT/306DT oil pump weakness makes this a frequent failure. We cover this in detail in our SDV6 case study.

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Any 306DT Vehicle with Multiple Secondary Faults

If your vehicle also needs a gearbox, air suspension or a new infotainment system, the cumulative repair cost can push the total well beyond the value of the vehicle – even if the engine alone would have cleared the threshold. Use our Repair vs Replace Calculator to factor in all costs.

Frequently Asked Questions

What is a 306DT engine failure and why is it so expensive?

The 306DT (3.0 TDV6/SDV6) suffers from crankshaft bearing failure – the tin‑aluminium coating on the bearings fatigues, leading to catastrophic seizure. Repair requires a full bottom‑end rebuild or a replacement engine, with labour intensive due to the engine's position. Typical reconditioned supply‑and‑fit costs range from £6,500 to £9,500 [EM-QUOTE].

How do I know if my 306DT failure is a write‑off?

Apply the 60% rule: divide your repair quote by the current trade value of your vehicle. If the result is above 0.6, it's a write‑off. For example, a £7,800 quote on a £9,000 car gives 87% – scrap. Use our calculator to run your own numbers.

Can I use a used 306DT engine to make it cheaper?

A used unit is cheaper (£3,500–£5,500 supply‑only) but comes with no warranty and unknown history. The 306DT is notorious for bearing failure, so a used engine may fail again soon. A reconditioned unit costs 30–45% more but includes new bearings, oil pump and a warranty – we generally recommend it if you're keeping the car. See our guide.

Which models are most affected by 306DT failure?

All models with the 306DT are affected – Discovery 4, Range Rover Sport (L494 and L320), Range Rover L405, Discovery 5 and Velar D300. Our enquiry data shows the highest volume comes from Discovery 4 owners, reflecting both the age of the vehicle and the high failure rate at around 80k–140k miles [PATTERN DATA].

Is it ever worth repairing a 306DT on a Discovery 4?

Yes – if the vehicle is in exceptional condition, has low mileage, or is a rare specification (e.g., HSE Luxury with full service history). In those cases, the car may be worth more than the average trade value, and the repair may clear the 60% threshold. Always get a professional valuation before deciding.

Does the 60% rule apply to the 306DT in a Range Rover Sport L494?

Yes, the same rule applies. L494 values are generally higher than Discovery 4, so a 306DT failure is less likely to be a write‑off on an L494. For example, a £15,000 L494 with a £7,800 quote gives a ratio of 52% – safe. However, older, higher‑mileage L494s may still fall into the watch zone.

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Genuine Enquiry DataBuilt from 9,000+ real 2025 UK Land Rover engine enquiries, not estimates.

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Fully Disclosed MethodWe publish our scrap‑threshold methodology openly on the framework page – no hidden assumptions.

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12 Vetted JLR SpecialistsEvery recommendation routes to a specialist who works on these engines daily – we don't send you to generalists.

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100% IndependentNo sponsors, no manufacturer influence – including when the honest answer is "don't repair it."

Is a 306DT Failure a Write-Off? The 60% Rule Applied