Everything on the TDV6/SDV6 V6 diesel: every vehicle it's fitted to, every known failure, real 2025 UK cost data, a genuine reliability verdict, and honest buying advice — built on 980 real enquiries.
The 306DT is a capable, torquey 3.0 V6 diesel with one defining weak point — catastrophic crankshaft bearing failure — and a genuinely strong overall reputation once that specific risk is understood and managed.
Full lineage, fitment, every known failure, real cost data and the complete verdict below.
Land Rover's diesel V6 lineage runs in a fairly straight line, and knowing where the 306DT sits in it explains a lot about why it behaves the way it does.
The 276DT, a 2.7-litre V6, was the first of this family and appeared in the Discovery 3 and early Range Rover Sport L320. It carried its own well-documented weak point — oil pump housing failure — and was replaced from around 2009 by the larger, more powerful 306DT. The step from 2.7 to 3.0 litres brought more torque and a stronger bottom end in most respects, but the crankshaft bearing design that defines the 306DT's own failure mode was carried through largely unchanged. From roughly 2020–2021, Land Rover began replacing the 306DT with the AJ20D6, a genuinely different straight-six architecture rather than an evolution of the V6 — the two are sometimes confused because they share the same D300 badge on some models, which is covered in detail on our AJ20D6 fitment guide. Understanding this lineage matters practically: a 306DT and an AJ20D6 badged identically as "D300" are not interchangeable, do not share the same failure profile, and should never be diagnosed or quoted as if they were the same unit.
| Model | Badge | Years | Notes |
|---|---|---|---|
| Discovery 4 | TDV6 / SDV6 | 2009–2016 | The single most-enquired host for this engine |
| Range Rover Sport L494 | SDV6 | 2013–2020 | Later, heavier vehicle — higher typical value |
| Range Rover L405 | TDV6 / SDV6 | 2012–2020 | Strong residual values throughout the range |
| Range Rover Sport L320 | SDV6 | 2009–2013 | Oldest, lowest-value host — highest scrutiny needed |
| Velar L560 | D300 | 2017–2020 | Pre-2021 units only; post-2021 D300 is AJ20D6 |
The badge alone rarely tells you which physical engine you have, particularly on the Velar and later Discovery Sport ranges where D300 spans two completely different architectures across the production run. If you're not certain, the fastest confirmation is our registration lookup tool, or checking the engine number stamp directly using our engine number location guide.
| Spec | Value |
|---|---|
| Configuration | 3.0-litre V6 turbodiesel |
| Power (TDV6, typical) | 245–256PS depending on tune |
| Power (SDV6, typical) | 288–306PS depending on tune |
| Torque | 600–700Nm depending on tune |
| Turbocharging | Twin-turbo, sequential |
| Emissions standard | Euro 5 (early) to Euro 6 (later revisions) |
| Timing drive | Chain, front-mounted |
Full oil, torque and service data on the 306DT technical reference page.
One catastrophic, well-documented weak point, and a small number of secondary issues that are far less urgent.
The defining risk. Catastrophic once advanced, typically 80,000–140,000 miles. Cold-start knock is the reliable early warning sign — full diagnosis and cost breakdown on the dedicated failure page.
Usually a secondary consequence of advanced bearing wear rather than an independent failure — bearing material entering the oil circuit damages the turbo bearings downstream.
As with most modern diesels, urban-heavy driving accelerates DPF-related issues on the 306DT specifically because its regeneration cycle needs sustained higher revs to complete fully.
| Condition | Supply Only | R&R Labour | Typical Fitted Premium |
|---|---|---|---|
| Used | £3,500–£5,500 | 15–20 hrs [EM-QUOTE] | £975–£1,300 [EM-QUOTE] |
| Reconditioned | £6,500–£9,500 | ||
| Rebuilt | £7,500–£11,000 |
Why the gap between used and reconditioned is worth understanding: a used 306DT carries no meaningful warranty and unknown history on the exact fault that defines this engine, which makes it a genuinely poor choice for anyone who can't verify the donor vehicle's service record. Reconditioned units are rebuilt to a known standard with the crankshaft bearing specifically inspected or replaced, which is precisely the part of the engine you're paying to insure against. Full worked economics on our Is a 306DT Failure a Write-Off? page.
Our full head-to-head verdict against the smaller, cheaper 204DTD.
The outgoing 2.7 V6 against its 3.0 successor.
The older V6 against the straight-six now replacing it.
The 306DT ranks 2nd among all Land Rover engines in our 2025 data at 980 enquiries, behind only the 204DTD — full ranking and methodology on the Engine Failure Index 2026, and the complete per-engine breakdown including mileage distribution on the 306DT failure rate page. It's worth being clear about what that ranking does and doesn't mean: a high enquiry count reflects how many of these engines exist on the road reaching typical replacement age as much as it reflects any inherent unreliability, a distinction explained fully on our data methodology page.
What actually matters if you're looking at a 306DT-powered vehicle right now.
Not just stamps — actual invoices showing oil grade and interval. Extended intervals correlate strongly with earlier bearing wear in our data.
Insist on starting the vehicle from genuinely cold, ideally first thing in the morning before viewing. A warmed-up demonstrator hides the earliest warning sign.
An otherwise excellent Discovery 4 with patchy history is still often a good buy if the price reflects the genuine possibility of a future engine bill.
"A strong, torquey diesel let down by one well-documented weak point — manage that one risk and the 306DT is a genuinely dependable engine."
The 306DT is not a bad engine. It is a good engine with one serious, well-understood failure mode concentrated in a specific mileage band. On the vehicles it's typically fitted to, replacement is financially sound in the large majority of cases against our 60% threshold, and full service history with disciplined oil-change intervals materially reduces the risk of ever facing that decision at all. Owners who understand this specific risk and buy or maintain accordingly tend to get many trouble-free years out of it.
Broadly yes, with one well-known catastrophic weak point: crankshaft bearing failure, typically between 80,000 and 140,000 miles. Outside of that specific failure mode, the 306DT is a capable, torquey V6 diesel with a strong reputation among independent specialists, and most examples with documented service history never experience the failure at all.
Discovery 4, Range Rover L405, Range Rover Sport L320 and L494, and early Range Rover Velar L560 D300 models built before 2021. It was sold under both the TDV6 and SDV6 names depending on model year.
Yes. TDV6 and SDV6 describe the same 3.0 V6 diesel family, badged differently at different points in its production run — SDV6 replaced TDV6 as the marketing name from around 2013 without a fundamental change to the core engine architecture.
With documented oil-change history at or ahead of interval, well past 150,000-180,000 miles is common. The crankshaft bearing risk is concentrated in a specific mileage band rather than being a certainty, and vehicles that pass through that window without symptoms rarely develop the fault afterward.
Treat it as a real risk factor rather than a dealbreaker. Budget mentally for the possibility of a reconditioned engine, have a specialist listen for cold-start knock before you buy, and use that uncertainty to negotiate price rather than walking away from an otherwise good vehicle.
980 Real EnquiriesEvery figure on this page traced to real 2025 UK data.
Every Failure LinkedFull mechanism and cost detail one click away, not buried in this page.
12 Vetted JLR SpecialistsEvery recommendation routes to a specialist who rebuilds 306DTs regularly.
100% IndependentNo sponsors, no manufacturer influence.
Compare quotes from our vetted specialist network, or check your own numbers first.
COMPARE QUOTES NOW → USE THE CALCULATOR