Built to Last, Built Complete: Introducing the D&J Precision Plus LML Duramax Long Block
Built to Last, Built Complete: The D&J Precision Plus LML Duramax Long Block
When an LML Duramax fails or reaches the end of its working life, truck owners face a tough choice. You want an engine that doesn't just replace factory parts; you want an engine that fixes factory weaknesses and cuts down on labor time during the swap.
At D&J Precision Machine, we engineered our 2011–2016 6.6L LML Duramax Remanufactured Long Block line in Cambridge, Ohio, with two goals in mind: absolute reliability and precise machining.
While our Essentials LML Long Block serves as a solid, cost-effective option, our Precision Plus Reman Long Block is designed for those who want the ultimate complete package, packed with upgrades, enhanced oil cooling, superior head sealing, and fewer parts to transfer from your old engine.
What Makes the LML Duramax Fail, And How We Fix It
The 2011–2016 LML Duramax is a great platform, but it has well-known issues:
- Head Gasket & Sealing Failures: Standard head bolts allow cylinder head stretch under heavy towing loads or increased boost, leading to blown head gaskets.
- Crankshaft & Camshaft Gear Slippage: Factory press-fit gears can slip under heavy stress, throwing engine timing completely out of sync.
- Oil Temperature Spikes: Under heavy service or towing, stock oil cooling systems struggle to keep oil temperatures in check, breaking down lubrication quality.
We didn't just rebuild the LML; we re-engineered it to eliminate these issues from the ground up.
Under the Hood: Key Upgrades in the Precision Plus Package
Here is how the Precision Plus brings durability and performance further than standard reman engines:
Superior Head Sealing & Clamping Strength
- ARP Head Studs + Tier 1 MLS Head Gaskets: Unlike standard stretch bolts, high-strength ARP head studs provide maximum clamping force to withstand elevated cylinder pressures, preventing head gasket failure even under heavy towing conditions.
Positive Mechanical Gear Retention
- Keyed Crankshaft & Camshaft: Both our Essentials and Precision Plus builds feature keyed crankshafts and camshafts to prevent gear slippage.
- Pinned Oil Pump: Precision Plus adds a pinned oil pump gear to guarantee constant, uninterrupted oil supply without the risk of gear spun-out failure.
Thermal Management & Lubrication Upgrades
- Upgraded L5P Oil Cooler: We retrofitted an upgraded oil cooler from the newer L5P platform to significantly reduce engine oil temperatures during extreme service.
- Extended RMC ETS Testing: Every Precision Plus engine doesn't just pass standard cylinder compression and cooling system integrity tests; we also perform in-house testing to verify oil pump pressure and oil flow volume before it ships.
Saving Time & Labor
One of the biggest headaches during an engine replacement is swapping over old, worn-out parts from your old core. The Precision Plus package dramatically reduces installation hassle by including components that traditional long blocks force you to transfer or source separately:
- Complete Top End Included: Rocker assemblies, valve covers, and intake manifold.
- Front & Rear Essentials Included: Harmonic balancer, flywheel, flex plate, and mounting hardware.
- Pre-Assembled Precision: Less time spent transferring parts means fewer technician hours on the bill (estimated install time is approx. 22 hours) and reduced risk of leaks or installation mistakes.
Precision Plus vs. Essentials: At a Glance
| Feature / Component | Essentials Long Block | Precision Plus Long Block |
|---|---|---|
| Ideal For | Daily drivers & tow rigs needing a reliable foundation | HD towers, shops, and owners wanting upgraded sealing & convenience |
| Pistons & Valvetrain | OEM-Spec Tier 1 Pistons, New Valves & Wear Parts | OEM-Spec Tier 1 Pistons, New Valves & Wear Parts |
| Crank & Cam Retention | Keyed Crankshaft & Camshaft | Keyed Crankshaft & Camshaft + Pinned Oil Pump |
| Head Sealing | Tier 1 Head Gaskets & Hardware | ARP Head Studs + Tier 1 MLS Head Gaskets |
| Oil Cooling System | Factory-Spec Oil Cooler | Upgraded L5P High-Flow Oil Cooler |
| Included Covers & Hardware | Basic Covers | Rocker Assemblies, Valve Covers, Intake Manifold, Balancer, Flywheel & Flex Plate |
| In-House RMC ETS Testing | Compression & Cooling System Integrity | Compression, Cooling, + Oil Pump Pressure & Volume Verification |
| Warranty Coverage | 24-Month / 100,000-Mile Parts + 24-Month Labor | 24-Month / 100,000-Mile Parts + 24-Month Labor |
Built and Tested in Cambridge, Ohio
Every single Precision Plus 6.6L LML Duramax engine is thoroughly inspected, precision-machined, and hand-assembled in-house by our team of experts at D&J Precision Machine. Before any engine leaves our facility, it undergoes rigorous RMC ETS testing to ensure perfect compression, cooling integrity, and oil delivery.
Whether you're a truck owner tired of dealing with your LML head gasket issues or a diesel shop looking for a drop-in long block you can install with total confidence, the Precision Plus is the ultimate choice for your Duramax.