2004 hummer h2 long blockpdf
2004 Hummer H2 Long Block: Complete Replacement & Installation Playbook
The 2004 Hummer H2—powered by General Motors' legendary 6.0L V8 LQ4 long block—is one of the most capable SUVs ever built. When that iron V8 finally throws a rod or suffers catastrophic failure, a long block replacement is often the smartest, most cost-effective path back to the trail. This playbook covers everything from identifying your engine code to installing a remanufactured long block and avoiding costly mistakes.
Key Takeaways
- The 2004 H2 uses the GM 6.0L V8 (LQ4) producing 325 hp and 360 lb-ft of torque; confirm your exact engine code before ordering any replacement long block.
- A long block includes the cylinder block, crankshaft, connecting rods, pistons, and camshaft—but not the heads, intake, exhaust, or accessories, so budget accordingly.
- Expect to pay $2,800–$5,500 for a quality remanufactured 6.0L long block, plus $800–$1,500 in labor if installed professionally.
- Core charges of $500–$1,200 are standard and typically refundable when you return your old block.
- Common failure points on the LQ4 include liftactor oil gallery feed tube failures (early 2004 models), water pumpweeps, and timing chain stretch at high mileage.
Understanding the 2004 Hummer H2 Engine
Factory Engine Specifications
| Specification | Details |
|---|---|
| Engine Family | GM LS-based V8 (Vortec 6000) |
| Displacement | 5,967 cc (363 cu in) |
| Configuration | 90° V8, OHV, 2 valves per cylinder |
| Bore & Stroke | 4.000" × 3.622" |
| Block Material | Cast iron |
| Crankshaft Material | Nodular (ductile) iron |
| Compression Ratio | 9.5:1 |
| Peak Horsepower | 325 hp @ 5,200 rpm |
| Peak Torque | 360 lb-ft @ 4,000 rpm |
| Engine Code (2004) | LQ4 (primary); LY2 in later model years |
| LS Family Identification | LS2-style main caps with cross-bolted design |
| Oil Capacity | 6 quarts (with filter) |
| Recommended Oil | 5W-30 synthetic blend or full synthetic |
What Is a Long Block?
A long block is a partially assembled engine core that provides the mechanical foundation of your powertrain without peripheral components. Understanding exactly what is included—and what is not—prevents surprises at the bill and ensures you order the right parts before pulling your stock engine.
Long Block vs. Short Block vs. Complete Engine
| Component | Long Block | Short Block | Complete / Built Motor |
|---|---|---|---|
| Cylinder Block | ✓ | ✓ | ✓ |
| Crankshaft | ✓ | ✓ | ✓ |
| Pistons & Connecting Rods | ✓ | ✓ | ✓ |
| Camshaft | ✓ | ✗ | ✓ |
| Cylinder Heads | ✗ | ✗ | ✓ (usually) |
| Valvetrain (rockers, lifters) | Varies | ✗ | ✓ |
| Oil Pan & Pump | Varies | ✗ | ✓ |
| Intake Manifold | ✗ | ✗ | ✓ |
| Timing Cover & Chain | Usually ✓ | ✗ | ✓ |
| Alternative Names | Reman long block | Crate engine core | Turnkey / built motor |
When to Replace the 2004 H2 Long Block
Not every engine problem requires a full long block swap. This section helps you diagnose whether a long block is the right call or if a lesser repair will suffice.
Signs Your LQ4 Needs a Long Block Replacement
- Loud knocking or rumbling from the lower engine—indicative of a thrown rod, bad main bearing, or cracked block.
- Low or zero oil pressure confirmed by a mechanical gauge after ruling out a bad sensor.
- Coolant mixing with oil (milky sludge on the dipstick or under the oil cap) that persists after a head gasket replacement—suggesting a cracked block or scored cylinder wall.
- Visible crankcase cracks around the main bearing caps or between cylinders on inspection.
- Severe piston or cylinder scoring from overheating, oil starvation, or foreign object ingestion.
- Engine has thrown a connecting rod through the block—almost always requires a new or sleeved block.
- Timing cover area with constant coolant seepage that cannot be repaired and has contaminated the timing chain area, leading to chain failure.
Problems That Do Not Require a Long Block
- Failed head gasket only (replace heads and gaskets, inspect block for scoring).
- Bad valvetrain components (lifters, rockers, pushrods) alone.
- Intake manifold gasket leaks.
- Water pump failure.
- Oil pan gasket leaks.
- Soleno id or minor sensor issues.
- Timing chain stretch without block damage (rebuild kit available).
How to Identify Your Exact 2004 LQ4 Engine Code
Ordering the wrong long block is the most common and expensive mistake H2 owners make. Follow these steps to confirm your engine before purchasing.
Step 1: Check the Engine Block Pad
- Locate the engine identification pad on the driver