2008 Hummer H3 3.7 Engine for Sale | OEM Used GM Atlas LLR Inline-5 DOHC (242
$2,400.00
At a Glance
- Condition: OEM used, compression tested across all 5 cylinders
- Availability: In stock, 2007 to 2010 H3 donor cores available
- Shipping: Free shipping to all 50 states via freight pallet, 5 to 10 business days
- All 5 cylinders compression tested, results available before you pay
- Engine identified as Atlas LLR (NOT the older 3.5L LK5)
- Donor application documented (H3, Colorado, or Canyon)
- Timing chain stretch inspected (common Atlas LLR high-mileage wear point)
- VVT (Variable Valve Timing) solenoid operation verified
- Cylinder head inspected for cracks
- 100% fitment verified before every order ships
- No core charge required
- Backed by a 15 day replacement warranty against internal defects
Description
About the 2008 Hummer H3 3.7 Engine
The Hummer H3 uses a powerful engine, the GM Atlas LLR engine, an inline-5 piston engine from the Atlas family of engines made by General Motors. This 2008 Hummer 3.7 engine for sale at Part Nests delivers robust acceleration, formidable off-road capabilities, and the distinctive sound of a GM straight-5.
The GM Atlas Family Explained
The Atlas family is a unique line of GM truck engines featuring an unusual inline-5 configuration alongside the more traditional inline-4 and inline-6 variants. The Atlas family included:
| Detail | Description |
|---|---|
| 2.8L LK5 (Inline-4) | Smaller variant, used in some Colorado and Canyon trims |
| 2.9L LLV (Inline-4) | Updated 4-cylinder variant, 2007 onward |
| 3.5L LK5 (Inline-5) | The original H3 engine in 2006 model year, 220 hp |
| 3.7L LLR (Inline-5, THIS LISTING) | The 2007-2010 H3 engine and 2007-2012 Colorado / Canyon variant, 242 hp |
| 4.2L LL8 (Inline-6) | The TrailBlazer / Envoy / Rainier engine, 270-291 hp |
The inline-5 LLR variant is what sets the H3 apart, delivering V6-equivalent power output (242 hp) with the characteristic torque curve and compact packaging of a longitudinal inline engine. The Atlas LLR was a well-engineered modern engine when introduced, with DOHC, variable cam timing on the intake side, and aluminum cylinder heads on a robust cast iron block.
LK5 vs LLR, Important Distinction
If you are searching for an H3 engine, you must confirm which generation you need:
- 2006 Hummer H3: Used the 3.5L LK5 Inline-5 (220 hp, 225 lb-ft), earlier, lower-output Atlas variant
- 2007 to 2010 Hummer H3: Used the 3.7L LLR Inline-5 (242 hp, 242 lb-ft), the upgraded engine, THIS LISTING
- 2008 onward H3 Alpha trim: Used the 5.3L LH8 V8 (300 hp), completely different engine, NOT this listing
The 3.5L LK5 and 3.7L LLR are mechanically related but NOT directly interchangeable without ECU and harness considerations. Confirm your year before ordering.
Application of the 2008 Hummer H3 Engine
The Atlas LLR engine was used across multiple GM mid-size truck and SUV applications:
- Hummer H3 (2007 to 2010): The primary application this listing covers. The H3 used the LLR exclusively from 2007 onward (replaced the earlier 3.5L LK5 from the 2006 model year).
- Hummer H3T (2009 to 2010): The pickup truck variant of the H3, also used the LLR.
- Chevrolet Colorado (2007 to 2012): The mid-size pickup that shared the Atlas LLR with the H3.
- GMC Canyon (2007 to 2012): The corporate cousin to the Colorado, also using the Atlas LLR.
- Off-Road Vehicle Conversions: Because of the durability and ample torque of the Hummer H3 3.7 engine, this engine has been adapted for use in dune buggies, Jeep conversions, and custom off-road builds.
- Light Commercial Conversions: The power-to-weight ratio and flexibility of the Atlas LLR makes it suitable for light commercial vehicle repower applications.
Key Features of the 2008 Hummer H3 Engine
- Performance: The H3 with the 3.7L LLR delivers strong off-road power with broad torque availability across the rpm range. The engine is designed for low-end grunt with adequate top-end power for highway driving.
- DOHC Architecture: Dual overhead camshafts with 4 valves per cylinder (20 valves total) provide better breathing than older OHV engines. The LLR is unambiguously DOHC despite some references to SOHC architecture in legacy documentation.
- Variable Valve Timing: The LLR features VVT on the intake camshaft, optimizing power and efficiency across the rpm range.
- Fuel Efficiency: The H3 with the 3.7L engine was not class-leading in fuel economy. EPA ratings were typical of the mid-size truck class of its era. Real-world fuel economy with the LLR ranges from 14 to 18 mpg combined depending on driving conditions.
- Transmission Pairings: The LLR was offered with a 5-speed manual transmission (more common on Colorado / Canyon, occasionally H3) or a 4-speed automatic Hydra-Matic 4L60-E (most common H3 pairing).
- Off-Road Capabilities: The H3 was specifically designed for off-road use, and the 3.7L LLR broad torque curve and durable construction support that mission. The H3 was approved for fording up to 24 inches of water with stock components.
- Towing Capacity: The 2008 Hummer H3 with the 3.7L LLR engine has a towing capacity of 3,000 to 4,500 pounds depending on the variant and the availability of the towing package.
- Technology: Compared to modern contemporary SUVs, the 2008 H3 cannot be considered a technology-rich vehicle. However, the engine is well-engineered with DOHC, VVT, and modern electronic fuel injection.
Signs You Need a Replacement LLR
- Timing chain rattle on cold start (the most common Atlas LLR high-mileage wear point)
- Loss of compression on one or more cylinders
- VVT cam phaser noise or fault codes
- Excessive oil consumption past piston rings
- Cylinder head crack symptoms (coolant loss, white smoke)
- Connecting rod or main bearing knock under load
- Donor H3, Colorado, or Canyon has been totaled and the engine is being moved to another chassis
Known LLR Issues We Inspect Before Shipping
- Timing chain stretch: The single most discussed Atlas LLR concern. The original-spec timing chains can develop slack at 100,000-plus miles, causing rattle on cold start that gets worse over time. Severe timing chain stretch can cause catastrophic engine damage. We inspect timing chain condition on every unit, document findings, and disclose before shipping.
- VVT solenoid wear: The intake VVT solenoid can develop wear or contamination, causing cam timing fault codes. We test VVT operation where accessible.
- Oil pressure / oil cooler: Some LLR engines develop oil pressure concerns related to internal oil cooler bypass. We document oil pressure indicators where available from donor diagnostic.
- Cylinder head cracking: A high-mileage LLR concern, particularly on engines that experienced overheating events. We inspect cylinder head visually before shipping.
Why Buy a Used Hummer H3 3.7 Engine
- Reliability: The Atlas LLR is fundamentally a robust GM truck engine, sharing parts and engineering with the high-volume Colorado / Canyon platform.
- Power: 242 hp and 242 lb-ft delivers respectable performance for the H3 vehicle weight.
- Versatility: The shared platform with Colorado and Canyon means parts availability remains good and engine swap support is well-documented.
- Cost Efficiency: Used LLR engines are an affordable repower option vs reman or new GM crate engines.
- Off-Road Heritage: The H3 was built for off-road, and the LLR was the engine that powered it through the H3 most-collected production years.
LLR Myth Busters
Myth: The Hummer H3 3.7L engine is ineffective and consumes excessive fuel.
Reality: The H3 with the 3.7L LLR was not the most fuel-efficient SUV on the market, but it was not catastrophically thirsty either. EPA fuel economy was comparable to other mid-size SUVs of similar power and off-road capability from the era (Pathfinder, Wrangler 4-cylinder, etc.).
Myth: The H3 3.7L engine is underpowered.
Reality: While not a high-performance engine, the 3.7L LLR 242 hp and 242 lb-ft are adequate for most driving conditions. The H3 was built as a dual-purpose vehicle (on-road comfort plus serious off-road capability), and the LLR delivers on both axes.
Myth: The Hummer H3 with the 3.7L engine is unreliable and requires constant maintenance.
Reality: Like any vehicle, proper maintenance is the foundation for reliability. The H3 had documented quirks (electrical concerns, occasional oil leaks), but these are not endemic problems with the LLR engine itself. Properly maintained H3s have logged 200,000-plus miles regularly, with the LLR continuing to perform.
Myth: The Hummer H3 3.7L is not powerful enough for towing or off-road.
Reality: The H3 with the LLR was officially rated to tow 3,000 to 4,500 lbs depending on variant and tow package. Off-road, the engine broad torque curve combined with the H3 4WD system and approach / departure angles delivers serious capability.
Myth: The Hummer H3 SUV is environmentally unfriendly because of its size and engine displacement.
Reality: The H3 was designed for a specific use case (off-road and adverse conditions), and its environmental footprint should be evaluated against that mission. The LLR is a modern fuel-injected engine with VVT and reasonable emissions performance for the era. Newer engine technologies have evolved since the H3, but the LLR remains a legitimate option for buyers needing the H3 platform off-road capability.
What Ships and What Does Not
| Item | Details |
|---|---|
| INCLUDED | Long block: cast iron block, crank, rods, pistons, camshafts, aluminum cylinder head with VVT, valve train, oil pan, valve cover, timing chain assembly. |
| NOT INCLUDED | ECU and harness (sold separately, application-specific to H3 vs Colorado vs Canyon), intake manifold (typical), exhaust manifold, throttle body, alternator, starter, A/C compressor, power steering pump, water pump, thermostat, transmission (4L60-E or 5-speed manual sold separately), motor mounts. |
| Fluids | Drained before shipping. Refill with 5W-30 (GM spec for LLR) full synthetic motor oil. Premium unleaded fuel not required, regular 87 octane is acceptable. |
| Core Note | No core charge. You are not required to return your old engine. |
Vehicle Compatibility
The 3.7L Atlas LLR fits the following GM vehicles:
| Vehicle | Compatibility |
|---|---|
| Hummer H3 | 2007 to 2010 (the H3 used the LLR exclusively, replacing the earlier 3.5L LK5 from 2006) |
| Hummer H3T | 2009 to 2010 (pickup variant, used same LLR) |
| Chevrolet Colorado | 2007 to 2012 (the most common LLR application; same engine as H3) |
| GMC Canyon | 2007 to 2012 (corporate cousin to Colorado, same engine) |
NOT compatible without modification:
- 2006 Hummer H3 (used the 3.5L LK5, not the 3.7L LLR)
- 2008 Hummer H3 Alpha trim (used the 5.3L LH8 V8, completely different engine)
- Hummer H1 / H2 (used different engine families entirely)
Verify your specific year and trim before ordering.
Inspection Workflow
Every used 2008 Hummer H3 3.7 engine we ship goes through this process:
- All 5 cylinders compression tested, pressure per cylinder recorded
- Engine identified as Atlas LLR (not the older 3.5L LK5)
- Timing chain stretch inspected (the most critical Atlas LLR wear point)
- VVT (Variable Valve Timing) intake cam phaser operation verified
- Cylinder head inspected for cracks
- Oil pressure indicators noted where available from donor
- Intake manifold and PCV system area inspected
- Donor application photographed and documented (H3, Colorado, or Canyon)
- Approximate mileage documented when verifiable
Why Buy From Part Nests
- All 5 cylinders compression tested, results available before you pay
- Engine identification confirmed (Atlas LLR, not older 3.5L LK5)
- Timing chain stretch inspection (the critical Atlas LLR wear point)
- VVT cam phaser operation verified
- Cylinder head crack inspection
- Donor application documented (H3, Colorado, or Canyon)
- Free freight pallet delivery to all 50 states
- No core charge, keep your old engine
- 15 day replacement warranty on internal defects
- Call (240) 306-7051 to confirm LLR generation (NOT older 3.5L LK5 or 5.3L LH8 V8 Alpha), donor application (H3, Colorado, or Canyon), and transmission pairing (4L60-E auto or 5-speed manual) before ordering
15 Day Replacement Warranty
Every used Hummer H3 3.7 Atlas LLR engine purchased through Part Nests carries a 15 day replacement warranty starting on the delivery date.
What Is Covered
- Internal defects already present when the engine arrives
- Compression failures on any of the 5 cylinders beyond what was disclosed
- Timing chain failures within 15 days from installation (where chain was documented as in-spec at shipping)
- VVT solenoid failures within 15 days from installation
- Cylinder head crack failures not disclosed at shipping
- Connecting rod, lifter, or bearing failures within 15 days from installation
- Incorrect generation shipped (LLR vs LK5 vs LH8 V8) due to an error on our end
What Is Not Covered
- Damage caused during installation
- Damage from running with neglected cooling system
- Damage from extended oil change intervals or incorrect oil viscosity (5W-30 GM spec required)
- Damage from incorrect ECU calibration for the H3 vs Colorado vs Canyon donor application
- Damage from running with a stretched timing chain that was not addressed at install (chain replacement may be advised at install for high-mileage cores)
- External components (ECU, harness, intake manifold, exhaust manifold, throttle body, alternator, starter, A/C, P/S, water pump, thermostat, transmission, motor mounts) unless itemized
- Labor expenses of any kind
To start a warranty claim, reach us within 15 days of delivery at (855) 634-4447.
- All 5 Cylinders Tested: Compression results documented before payment
- LLR Generation Confirmed: 3.7L LLR (NOT older 3.5L LK5 or 5.3L LH8 V8 Alpha)
- Timing Chain Stretch Inspected: The critical Atlas LLR high-mileage wear point
- VVT Cam Phaser Verified: Intake variable valve timing operation tested
- Donor Application Documented: H3, Colorado, or Canyon origin identified
- 15 Day Replacement Cover: Internal defects protected from delivery onward
Additional information
| aspiration | Naturally Aspirated |
|---|---|
| camshaft-type | DOHC (Dual Overhead Camshaft) |
| combustion-system | Electronic (Multi-Point) Fuel Injection |
| compression-ratio | 10.0:1 |
| configuration | Inline-5 |
| cylinder-block-alloy | Cast Iron |
| cylinder-bore | 95.5 mm |
| piston-stroke | 101.6 mm |
| valve-train | DOHC, 4 valves per cylinder, 20 valves total |
| variable-valve-timing | Yes (intake cam) |
| engine-family | GM Atlas (LLR variant) |
| rpo-code | LLR |
| displacement | 3.7 liters (3, 653 cc / 223 cu in) |
| horsepower | 242 hp at 5, 600 rpm |
| torque | 242 lb-ft at 4, 600 rpm |
| vehicle-curb-weight-h3 | 4, 700 to 4, 900 lb (NOTE: this is vehicle weight, not engine weight, engine alone is approximately 370 to 400 lb) |
| towing-capacity-h3 | 3, 000 to 4, 500 lbs |
| originally-mated-with | 5-speed manual or 4-speed automatic (Hydra-Matic 4L60-E) |
| production-years-llr | 2007 to 2012 |
| Brand | GM |
Two Atlas inline-5 displacements with different power outputs. The 3.5L LK5 (220 hp, 225 lb-ft) was the original H3 engine in 2006 model year, and was also used in some early Colorado / Canyon trims. The 3.7L LLR (242 hp, 242 lb-ft) replaced the LK5 starting in the 2007 model year for the H3 and 2007-2012 for Colorado / Canyon. The LLR uses a longer stroke crankshaft and revised cylinder head versus the LK5. The two are mechanically related but NOT directly interchangeable without ECU and harness considerations. The 2008 model year H3 listed here uses the 3.7L LLR exclusively (unless equipped with the 5.3L LH8 V8 Alpha trim).
The most-discussed Atlas LLR high-mileage wear point. The original-spec Atlas LLR timing chains can develop slack at 100,000-plus miles, causing rattle on cold start that gets progressively worse over time. Severe timing chain stretch causes loss of camshaft timing accuracy and can lead to catastrophic engine damage if not addressed. We inspect timing chain condition on every LLR before shipping and disclose findings. Best practice at engine installation: if the timing chain shows stretch indicators, plan for chain replacement during install (the upgraded GM timing chain kits resolve the original-spec slack issue).
GM mid-size truck engine family with inline-4, inline-5, and inline-6 variants. The Atlas family includes: 2.8L LK5 Inline-4 (smaller Colorado / Canyon), 2.9L LLV Inline-4 (updated 4-cylinder, 2007+), 3.5L LK5 Inline-5 (2006 H3, 220 hp), 3.7L LLR Inline-5 (2007-2010 H3, 2007-2012 Colorado / Canyon, 242 hp), and 4.2L LL8 Inline-6 (TrailBlazer / Envoy / Rainier, 270-291 hp). The inline-5 variants are unusual; most automakers use inline-4 or inline-6 layouts, and the inline-5 character with its distinctive sound is one of the H3 features.
Yes for 2007-2012 trucks with the 3.7L V6 trim (actually inline-5). The 3.7L LLR was used in 2007-2012 Chevrolet Colorado and 2007-2012 GMC Canyon. Confirm your specific year and trim when ordering. Pre-2007 Colorado / Canyon may have used the 3.5L LK5 or other earlier Atlas variants. Tell us your year and trim and we will match the correct LLR engine. Note: the LLR is sometimes referenced as a "V6" in casual conversation but is technically an Inline-5 (I5) engine.
No. The 2008-2010 Hummer H3 Alpha is a different trim that uses the 5.3L LH8 V8 (300 hp), not the 3.7L LLR Inline-5. The H3 Alpha was positioned as the higher-performance H3 variant for buyers wanting V8 power and higher tow capacity. If you have a 2008 H3 Alpha and need a replacement engine, you need a 5.3L LH8 V8 listing, not this LLR Inline-5 listing. Confirm your specific trim when ordering.
5-speed manual or 4L60-E 4-speed automatic. The LLR was factory-paired with the Aisin AR-5 5-speed manual transmission (more common in Colorado / Canyon, occasionally in H3 Alpha trim) or the GM Hydra-Matic 4L60-E 4-speed automatic (the most common H3 pairing). The 4L60-E was used across many GM mid-size and full-size applications. Tell us your existing transmission and donor application and we will confirm correct flexplate, ECU calibration, and harness compatibility.
Packaging and torque character. GM chose the inline-5 layout for the Atlas mid-size truck program because it offered a longer stroke (better low-end torque) and better packaging in the H3 / Colorado / Canyon engine bay than a V6 of equivalent displacement would have. The inline-5 produces a distinctive sound (a half-step between an inline-4 and inline-6) that has become part of the H3 character. Inline-5 layouts are rare in modern automotive design, with the Atlas family and the Audi 2.5L TFSI five-cylinder being among the few production examples.
No. There is no core return required.
2 reviews for 2008 Hummer H3 3.7 Engine for Sale | OEM Used GM Atlas LLR Inline-5 DOHC (242
Related products
Tobias L. –
Got a 3.7L LLR for a 2008 Hummer H3 replacement. Generation correctly identified as LLR (not the older 3.5L LK5 or the 5.3L LH8 V8 Alpha), all 5 cylinders compression tested, timing chain stretch inspection clean, VVT solenoid operation verified. Honest pre-purchase information about the H3 vs H3 Alpha distinction and the Inline-5 sound character.
Hayley G. –
Sourced an LLR for a 2009 GMC Canyon repower. Donor application from a similar Colorado / Canyon chassis, ECU calibration documented for matching to the 4L60-E transmission. Honest pre-purchase information about the LLR’s timing chain stretch concern and the recommended chain replacement at install for high-mileage cores. Foundation for keeping the Canyon working.