Applicable Engine:
LLY / LBZ
Applicable Brand:
GMC / Chevrolet
Applicable Car:
Silverado / Express Van
Product parameters:
| Displacement | Fuel | Cylinder | Vale | Camshaft | Year |
| 6.6L |
Gasoline
|
4 | 16 | 1 | 2004- |
Cylinder Head
Cylinder Head for GMC Chevrolet Duramax LLY LBZ 6.6L Turbo Diesel 97779579 98025702
Introduction
Product NO.
| ML NO. | OEM NO. | REF NO. |
| MLG064A | 97779579 | |
| MLG064B | 98025702 |
Product Information Cylinder Head
1. Product Overview
The LLY (2004.5–2005) and LBZ (2006–2007) are both 6.6L V8 turbocharged diesel engines from GM’s Duramax family, featuring cast aluminum cylinder heads, 32-valve DOHC valvetrain, and common rail direct injection. They are known for strong towing performance, efficiency, and mechanical durability.
Both engines use similar cylinder heads with minor differences in coolant port designs and emissions sensor locations, making replacement heads mostly interchangeable with small modifications.
2. Technical Specifications
| Item | LLY / LBZ |
|---|---|
| Engine Displacement | 6.6L (6599 cc) |
| Engine Type | V8, 90° |
| Cylinder Head Material | Cast Aluminum |
| Valvetrain | DOHC, 32-Valve (4 valves per cylinder) |
| Aspiration | Turbocharged with intercooler |
| Fuel System | High-pressure common rail (Bosch) |
| Head Bolts | 18 per head (torque-to-yield) |
| Cooling | Water-cooled |
| Turbo Type | Variable Geometry Turbo (VGT) |
| Emissions | LLY: no DPF, LBZ: pre-DPF (no SCR/DEF yet) |
3. OEM & Reference Part Numbers
| Engine | OEM Cylinder Head Number |
|---|---|
| LLY | 98055650 / 98055651 (L/R) |
| LBZ | 98060819 / 98060820 (L/R) |
| Casting Codes | 97229810, 97229808, 98060819, 98055650 |
Both LLY and LBZ heads can be used interchangeably with slight port gasket differences.
4. Compatible Vehicles
| Make | Model | Years | Engine |
|---|---|---|---|
| Chevrolet | Silverado 2500HD / 3500 | 2004.5–2007 | LLY / LBZ |
| GMC | Sierra 2500HD / 3500 | 2004.5–2007 | LLY / LBZ |
| Chevrolet | Express Van 2500 / 3500 | 2006–2007 | LBZ |
| GMC | Savana Van 2500 / 3500 | 2006–2007 | LBZ |
| Chevrolet / GMC | Kodiak / Topkick C4500+ | Some variants | LLY / LBZ |
5. Product Options
| Type | Description |
|---|---|
| Bare Cylinder Head | Casting only – no valves or cams |
| Loaded Head | Includes valves, valve guides, seals, retainers, keepers |
| Complete Assembled Head | Fully built with valves, springs, camshafts, injectors seats (if needed) |
High-strength cast aluminum
Pressure tested to 150 psi
CNC-machined deck surface and cam journals
Compatible with OEM rocker assemblies and head gaskets
6. Installation Notes
- Use new torque-to-yield (TTY) head bolts or ARP studs
- Follow GM torque sequence: multiple stage torque-angle procedure
- Clean all bolt threads and apply GM-recommended sealant/oil
- Replace head gasket with high-quality MLS type (Mahle, Victor Reinz)
- Verify injector cup sealing (LLY/LBZ use pressed-in injector cups)
- Prime oil system before first start and check coolant pressure
7. Common Cylinder Head Issues & Repair Advice
| Issue | Symptoms | Cause | Recommended Fix |
|---|---|---|---|
| Cracked Cylinder Head | Coolant in oil, white smoke | Overheat or poor casting | Replace head, inspect for coolant cross-leak |
| Warped Deck Surface | Blown head gasket | Overheating or improper torque | Resurface and use upgraded head gaskets |
| Injector Cup Leak | Coolant in cylinder, misfire | Failed cup seal | Replace cups and reseal with Loctite or equivalent |
| Coolant Cross-Contamination | Random misfire, pressurized coolant | Casting porosity or warp | Replace head, pressure test block |
| Valve Seat Erosion | Power loss, compression drop | Poor fuel or overheat | Replace seat or full valve job |
8. Export & Service Markets
- USA & Canada: Primary market (HD trucks, vans)
- Mexico / Central America: Exported HD pickups
- Africa: Towing fleet & rebuilt engine market
- Middle East: Used HD fleet and custom vehicle platforms
- Australia / NZ: LHD-to-RHD converted Dually trucks
- South America: Custom diesel conversion market