We provide and install Jaguar 3.0 engines across the UK, including the twin-turbo 306DT diesel and the supercharged AJ126 petrol, which power models like the XF, XJ, F-Type, and F-Pace. Each engine is verified by its unit code, tested for performance, and comes with a warranty.
Compare matching engine codes, valve counts, actual CC and power outputs linked to this engine size.
| Make | Model | Engine Code | Valves | Actual CC | Power kw / hp | Year Range | Action |
|---|---|---|---|---|---|---|---|
| Land Rover | Discovery 4 | 306DT | 24 | 2993 | 155 kw / 211 hp | 2009-continue | Get Quote |
| Land Rover | Discovery 5 | 306DT | 24 | 2993 | 155 kw / 211 hp | 2016-continue | Get Quote |
| Jaguar | F-Pace | 306DT | 24 | 2993 | 177 kw / 241 hp | 2015-continue | Get Quote |
| Jaguar | XF | 306DT | 24 | 2993 | 177 kw / 241 hp | 2008-2015 | Get Quote |
| Jaguar | XF Sportbrake | 306DT | 24 | 2993 | 177 kw / 241 hp | 2012-2014 | Get Quote |
| Jaguar | XJ | 306DT | 24 | 2993 | 177 kw / 241 hp | 1996-2003 | Get Quote |
We have complete expertise in both Jaguar 3.0 engines. This includes the 306DT twin-turbo V6 diesel (used in XF, XJ, and F-Pace models from 2009 to 2020) that produces between 211 and 300 bhp with 600 Nm of torque. We also work on the AJ126 supercharged V6 petrol (found in XF, XJ, F-Type, and F-Pace models from 2012 to 2020) that produces 340 to 400 PS using an Eaton TVS R1320 supercharger. Each engine is different and requires specific diagnostic methods.
When we replace an engine, we ensure it is code-matched, ECU-verified, and checked for all parts. This process considers the key differences between the 306DT diesel and AJ126 petrol engines, including their cooling systems, boost control, and transmission setups.
We handle everything in-house: sourcing, stripping, machining, reconditioning, quality control, and installation. There are no outsourced steps.
You can save thousands compared to Jaguar’s franchised rates. We offer up to 12 months of warranty and guarantee the quality of every 3.0 engine we supply or install.
The Jaguar 3.0 has two different types: the 306DT V6 diesel and the AJ126 supercharged V6 petrol. Each type has its own common problems. At Britannia Rebuilds, we find the exact issue on the right platform before suggesting any fixes.
| Problem | Early Causes | Solution |
|---|---|---|
| Crankshaft failure (Diesel) | Narrow bearing design on the 306DT V6 diesel leads to oil starvation under sustained motorway driving, the most critical and well-documented failure on Jaguar diesel models. | Full long-engine replacement with a reconditioned or rebuilt unit. Bottom-end rebuilds alone are rarely viable once the crank scores the block. |
| Timing chain & tensioner failure (SC Petrol) | On the AJ126 supercharged V6, the steel tensioner piston wears the aluminium guide backing, causing chain slack. Can fail without warning, destroying valves and pistons. | Replace timing chains, tensioners, and guides as a complete kit. Preventative replacement is strongly recommended on engines over 60,000 miles. This is a known design weakness. |
| Water pump failure (SC Petrol) | Coolant gets inside the bearing housing, corroding the impeller shaft and causing the pump's mechanical seal to fail — sometimes in under 20,000 miles on early supercharged models. | Replace the water pump and the small coolant pipe connected to it (fragile plastic connectors break on removal). Flush the cooling system and check for overheating damage. |
| Plastic coolant pipe cracking (SC Petrol) | Two-piece cross-over pipes at the front of the AJ126 have plasti-welded seams that split with age causing massive coolant leaks. Y-pipe and expansion tank hose are also vulnerable. | Replace all plastic cross-over pipes with aluminium aftermarket alternatives. Replace the expansion tank hose at the same time. 2017+ models have improved single-piece pipes. |
| Throttle body cracking (Diesel) | Plastic throttle body warps or cracks on the 306DT — a Jaguar-specific issue that triggers restricted performance and blocks DPF regeneration, leading to secondary DPF failure. | Replace throttle body with updated part. Check intake manifold for cracks around the rocker cover seal area. Reset adaptations via Jaguar diagnostics. |
| Supercharger coupler wear (SC Petrol) | The Eaton supercharger torsion isolator/coupler wears on early V6 and V8 models causing a metallic rattle on cold start and a distinctive "clonk" on engine shutdown. | Replace the supercharger coupler with the revised version (updated around 2018 MY). Listen for metallic rattle on cold start and clonk on shutdown as diagnostic indicators. |
| Oil dilution from DPF regen (Diesel) | Extra diesel injected during DPF regeneration bypasses piston rings into the sump, diluting the oil. Frequent short journeys massively accelerate this — a known 306DT characteristic. | Change oil every 6,000–8,000 miles (not factory 21,000). Monitor oil level digitally. Never exceed maximum mark. Avoid habitual short journeys. |
| Turbocharger failure (Diesel) | Oil starvation, VGT vane seizure, or DPF back-pressure overloading the sequential twin-turbo bearings — particularly on high-mileage XF and F-Pace diesel models. | Inspect turbo shaft play, oil feed/return lines, and DPF. Replace turbo and address root cause. A new turbo on a blocked DPF will fail again. |
Note: The 306DT diesel and AJ126 supercharged petrol share nothing but a displacement figure. They require completely different diagnostic approaches, tooling, and specialist knowledge — and we have both.
Every Jaguar 3.0, whether diesel or supercharged petrol, goes through thorough checks and precise machine work before it is reconditioned. This process focuses on restoring compression, oil pressure, timing accuracy, and the high performance that Jaguar owners expect.
Electronic fault tracing is combined with compression, leak-down, and lubrication analysis to determine whether the engine is structurally suitable for reconditioning.
The unit is dismantled to core level and cleaned thoroughly to remove carbon, sludge, coolant residue, and metallic debris without compromising machined surfaces or gallery integrity.
Cylinder geometry, crank journals, deck flatness, valve train wear and bearing tolerances are measured precisely, with honing, resurfacing, and seat correction carried out where required.
The engine is rebuilt using renewed wear components, updated timing and sealing hardware, and torque-angle assembly procedures to restore mechanical precision and durability.
Final testing verifies oil pressure, idle stability, thermal behaviour, and ECU compatibility so the finished engine delivers factory-level refinement and dependable performance.
Every Jaguar 3.0 replacement is validated for engine code accuracy, diesel/petrol variant matching, ECU compatibility, and Jaguar-specific drive mode and transmission integration.
Recent customer feedback from owners who used our engine supply, replacement, and fitting services.
They sourced the correct engine for my vehicle and the whole process was smooth from start to finish. Great communication and professional service throughout.
The rebuilt engine is perfect and running like new. I saved a significant amount compared to the main dealer and received fantastic advice and support. Very happy!
They verified my engine code, supplied the right engine and fitted it perfectly. Their knowledge and attention to detail gave me total peace of mind. Highly recommended.
Reconditioned engine supplied and fitted in less time than expected. The workshop team were professional and kept me updated at every stage.
View genuine workshop images that show the quality of our ongoing work, completed replacements and finished results.
Replacing a Jaguar 3.0 engine requires specialised knowledge since the 306DT diesel and AJ126 supercharged petrol engines are fundamentally different, despite having the same displacement. At Britannia Rebuilds, we assess each engine type based on specific criteria: diesel engines are checked for crankshaft bearing condition, oil dilution, turbo health, and DPF status, while supercharged petrol engines are evaluated for timing chain tension, water pump integrity, coolant pipe condition, and supercharger coupler wear.
If you're looking for a Jaguar 3.0 engine, we have a variety of tested, used, rebuilt, and reconditioned 306DT engines available for the XF, XJ, F-Pace, and XF Sportbrake. For supercharged petrol owners, we stock AJ126 engines for the XF, XJ, F-Type, and F-Pace, offering both 340 bhp and 380 bhp options. All engines are verified with Jaguar codes before sale.
The 306DT diesel engine carries similar crankshaft risks as its Land Rover counterpart, along with specific issues such as throttle body cracking and oil dilution from DPF regeneration. The AJ126 supercharged petrol engine has its own issues, including timing chain tensioner flaws, early water pump failure, and brittle coolant pipes. We address these common problems during our reconditioning process, ensuring that your Jaguar performs reliably and powerfully.
Quick answers about Jaguar engine supply, fitting, rebuilds, reconditioning, and warranty-related questions.
