HUMMER H2 · GMT820-BASED · 2003–2009

Hummer H2

GMT820-BASED LADDER FRAME6.0 LQ4 · 6.2 L92 V8BW 44-84 FULL-TIME 4WDEATON REAR E-LOCKERSUV · SUT

“GM took a Suburban frame, cut seven inches out of the middle and wrapped it in Hummer-shaped bodywork. Purists called it a costume. It turned out to be a full-time 4WD truck with a rear locker and 35s from the factory, and it handles a rough trail better than most of the people who bought it ever found out.”

PART 01

Overview

Where it came from, why it matters, and how it changed year to year.

The story

The H2 is what happened when General Motors bought the most famous name in off-roading and decided it should sell in volume. AM General built it under contract in a new plant in Mishawaka, Indiana, but GM engineered it from its own truck parts: a shortened Suburban frame, a three-quarter-ton front end and a 6.0-liter small-block V8. It went on sale as a 2003 model for less than half the price of an H1. Car and Driver took one 2,000 miles through Baja and decided it was 'not a Hummer poseur'. It was something else, and that's mostly fine.

FROM SHOW CAR TO SUBURBAN FRAME

In December 1999 GM bought the rights to the Hummer name from AM General, and the H2 was the first product of that deal. GM showed an H2 concept in 2000 with independent rear suspension, then priced it out of the production truck. Wikipedia credits the design to Clay Dean; the Chicago Tribune named Terry Henline as chief designer when the pickup concept appeared at the 2001 New York show. GM's 2003 spec sheet named the H2's rivals as the Range Rover, the Lexus LX 470 and the Lincoln Navigator, so luxury buyers were the target from the start.

The production recipe was pure GM parts bin. Engineers took a Suburban frame, cut 7.2 inches out of its middle for a 122.8-inch wheelbase and trimmed the overhangs, giving a truck nine inches shorter than a Tahoe. The torsion-bar front suspension came from a 2500-series Suburban, the rear became a five-link live axle on coils, and GM said a diesel wouldn't package. The radiator support and engine box are welded to the body, so the big front-hinged hood doesn't shimmy against the rest of the truck.

WHAT IT ACTUALLY DOES IN THE DIRT

Under the costume is a serious drivetrain. A full-time BorgWarner 44-84 transfer case sends 60 percent of the torque to the rear, locks 50/50 at any speed and has a 2.64:1 low range. The 4.10 rear axle carries an Eaton ELocker that engages only in 4LO below 20 mph. Bosch ABS and traction control are tuned for rough ground, and skid plates cover the engine, transfer case and fuel tank. The front chin plate has 'H2' embossed on it, because of course it does.

GM's figures give the coil-sprung truck a 40.4-degree approach and a 39.6-degree departure angle, and the off-road package's LT315/70R17s push the approach to 43.6 degrees. Ground clearance is about ten inches against the H1's sixteen, so in Baja Car and Driver learned to put a tire on the rock rather than straddle it. The optional rear air suspension can lift the tail about two inches and runs an air hose for the tires. The H1's central tire inflation wouldn't work with GM's axles.

THE PICKUP, THE 6.2 AND THE END

The SUT arrived for 2005: an H2 with a short bed and an Avalanche-style Midgate that folds to open the cabin into the bed. US sales peaked at 34,529 in 2003 and slid as fuel prices rose. For 2008 GM gave the H2 a new interior, a 393-hp aluminum 6.2-liter V8 and the six-speed 6L80. Towing went from 6,500 to 8,000 pounds and the crawl ratio rose to about 39:1. Owners rate those last trucks the best H2s, and they're the hardest to find.

The timing couldn't have been worse. GM put Hummer up for sale in 2008, and a deal with China's Tengzhong collapsed in February 2010. H2 production ended in 2009. Avtotor in Kaliningrad, Russia, had also assembled H2s from 2006 to 2009. GM's US sales figures add up to 153,026 H2s. The Mishawaka plant was sold in 2017 to SF Motors, a maker of electric vehicles.

SIDEBAR · THE 8,500-POUND LOOPHOLE

Why there's no EPA sticker

The H2's gross vehicle weight rating is 8,600 pounds. Until 2011 the EPA exempted vehicles over 8,500 pounds GVWR from fuel-economy testing and standards, so GM never had to publish a rating, and H2s didn't count toward its fleet average.

Magazines measured it themselves. Car and Driver and Motor Trend both recorded about 10 mpg, Edmunds 9.2 and Four Wheeler 10.8. With a 32-gallon tank, H2 owners on 37s still stop for fuel 'long before I need to pee', as one forum owner put it.

A yellow Hummer H2 with a chrome brush guard and HUMMER door graphics kicking up dust on a dry dirt field — H2 · DIRT FIELD, POLAND

Year by year

What changed, model year by model year. Sweet spot Beware Recall

Best years across every AM General Hummer generation →

1999In December, GM buys the Hummer name from AM General; AM General keeps building the trucks
2000GM shows the H2 concept, which has independent rear suspension that the production truck drops
2001The H2 SUT pickup concept, with an Avalanche-style Midgate, is shown at the New York auto show
2003The production H2 goes on sale in 2002 as a 2003 model, built by AM General in Mishawaka: 6.0 L LQ4 V8, 4L65-E four-speed, BorgWarner 44-84 full-time transfer case, standard Eaton rear ELocker, 4.10 axles
2003First-year recalls: two wiper-motor campaigns (02V283000, 08V456000), the key and shifter override (03V075000) and the Hydro-boost relief valve (04V045000, also 2004)Recall
2004–2005Hydro-boost accumulator (05V043000) and second-row center seat belt routing (05V163000) recallsRecall
2005The H2 SUT pickup goes on sale; the 6.0 is now rated at 325 hp and 365 lb-ft
2005–2007Owners say the front diff was strengthened and build quality improved from mid-2005; one owner would choose a 2005.5–07 truck over a 2003
2006Avtotor begins licensed H2 assembly in Kaliningrad, Russia (to 2009). Power steering hose recall 05V455000
2006–2009Heated washer fluid module recalls (08V441000, then 10V240000 after new fire reports)Recall
2008Major update: 6.2 L L92 V8 (393 hp, 415 lb-ft), 6L80 six-speed, towing up to 8,000 lb, crawl ratio about 39:1, stronger transfer case, quicker steering, new interior with a rotary 4WD dial, curtain airbags and panic brake assist. Owners call the 2008–09 trucks the most refined H2sSweet spot
2009Last year. Production ends as GM tries to sell Hummer; the planned Black Chrome Limited Edition stops at six trucks, according to Wikipedia

PART 02

Specs & capability

How it’s built, what it can do, and what fits under it.

How it’s built

The H2 sits on a modified GMT820 ladder frame: a GM three-quarter-ton front section and a shortened half-ton Suburban rear. It has torsion-bar independent front suspension, a five-link coil-sprung rear axle with an optional air-spring rear, and full-time 4WD through a BorgWarner 44-84 transfer case. The 6.0-liter LQ4 and four-speed 4L65-E powered it through 2007, then the 6.2-liter L92 and six-speed 6L80 for 2008–09. Wheels are 8-lug, 8 x 165.1 mm.

CHASSISShortened Suburban ladder frame, 122.8 in wheelbaseCar and Driver: 7.2 in cut from the middle. Wikipedia describes a modified GMT820 three-quarter-ton front with a half-ton rear section.

FRONT SUSPENSIONIndependent, torsion barsControl arms and torsion bars from the 2500-series Suburban. Ride height is adjusted at the torsion-bar keys.

REAR SUSPENSIONFive-link live axle, coils or air springsOptional self-leveling rear air springs (RPO ZM6) lift the tail about 2 in. The rear axle is an AAM 9.5-inch 14-bolt semi-float, according to owners.

4WD SYSTEMBorgWarner 44-84 full-time, lockable center diff40/60 front/rear split, 2.64:1 low range. Modes: 4HI, 4HI Lock, 4LO Lock and Neutral for flat towing.

LOCKERSEaton ELocker rear, standardWorks only in 4LO Lock and disengages above 20 mph. Brake-based traction control handles the front axle.

ENGINE6.0 L LQ4 V8 (2003–07) · 6.2 L L92 V8 (2008–09)The LQ4 made about 315–325 hp. The aluminum-block L92, with variable valve timing, made 393 hp and 415 lb-ft.

Variants & engines

YEARS	PLATFORM	ENGINE	OUTPUT	WORTH KNOWING
2003–2004	H2 SUV	6.0 L LQ4 V8	315 hp / 360 lb-ft (GM preliminary)	Four-speed 4L65-E, 4.10 axles, LT315/70R17 tires on GM's spec sheet. The rear air suspension came with the Adventure package.
2005–2007	H2 SUV	6.0 L LQ4 V8	325 hp / 365 lb-ft	Re-rated engine, same four-speed. Owners say the front diff and build quality improved from mid-2005.
2005–2007	H2 SUT	6.0 L LQ4 V8	325 hp / 365 lb-ft	Short bed, Midgate and an outside swing-away spare. Car and Driver priced a test truck at $52,845.
2008–2009	H2 SUV / SUT	6.2 L L92 V8	393 hp / 415 lb-ft	Six-speed 6L80, new interior, 8,000 lb towing, crawl ratio about 39:1, stronger transfer case, quicker steering. Lower bumpers painted silver.
2006–2009	H2 (Avtotor)	As US	—	Licensed assembly in Kaliningrad, Russia.

Capability numbers

Towing7,000 lb (3,182 kg) 2003 · 8,000 lb (3,629 kg) 2008–09GM figures; GM's 2008 release gives the outgoing truck's rating as 6,500 lb

GVWR8,600 lb (3,901 kg)2003 GM spec

Fuel tank32.0 US gal (121 L)Owner's manual

Ground clearance10.0 in (254 mm) coil · 10.5 in (267 mm) air9.9 in under the differentials; 2003 GM spec

Approach / departure / breakover40.4° / 39.6° / 25.8° (coil)41.7° / 38.1° / 26.6° with air suspension (GM). Car and Driver quoted 43.6° approach on the off-road package's LT315s

Wading depth24 in (508 mm)GM, 2008 H2 announcement

Step climb16 in (406 mm)GM, 2008 H2 announcement

Grade / side slope60% / 40%2003 GM spec

Crawl ratio33:1 (4L65-E) · about 39:1 (6L80)2.64:1 low range, 4.10 axles

Fuel economyNot EPA-ratedExempt because GVWR is over 8,500 lb. Tested: 9–10.8 mpg (Car and Driver, Motor Trend, Edmunds, Four Wheeler)

Curb weight6,400 lb (2,909 kg) 6.0 · 6,614 lb (3,000 kg) 6.2GM spec · Wikipedia

Turning circle43.5 ft (13.5 m) curb to curb2003 GM spec

Wheels & tires

Try the tire fitment tool: biggest tire at every lift →

FACTORY TIRES

LT315/70R17 (GM 2003 spec sheet; about 35 in)325/50R22 (22-inch factory option, per Limitless Tire)

Bolt pattern8x165.1 (8x6.5")

Center bore117 mm

Lug threadM14x1.5

Lug-nut torque140 lb-ft (190 N·m)

LIFT	BIGGEST TIRE	WHAT IT TAKES
Stock	37x12.50R17	On stock wheels or the same offset. One owner runs them at stock height with a slight torsion-bar crank and doesn't rub at full stuff, apart from a scrub on the sway bar at full lock (stock 35s do the same). 37x14.50s didn't fit.
≈2 in (leveling / torsion keys)	38 in	One owner runs 38s with no lift and a leveling kit; another used GM's 'green' torsion keys to gain about 2 in up front for 38s. Owners warn cranked torsion bars ride harder and wear the steering linkage faster.
4 in suspension (+1 in body)	37–38 in	Owners report 37s on a 4-in Rancho lift with a 1-in body lift, and 38-in Mickey Thompson Baja MTZs on a 4-in Rancho.
6 in	40x13.50	Fabtech 6-in lifts on 40s are common. Owners recommend wheels with 4.5-in backspacing. The lift drops the torsion bars and crossmember lower under the truck.

Forum consensus, not a guarantee: wheel offset, tire brand and suspension wear all change clearance. Confirm before you buy.

Production & special editions

AM General built the H2 for GM in a plant that opened in Mishawaka, Indiana, in 2002. GM said the plant could build 40,000 a year; Avtotor also assembled H2s in Russia from 2006 to 2009.

US sales (GM, by calendar year)2002 18,861 · 2003 34,529 · 2004 29,898 · 2005 33,140 · 2006 17,472 · 2007 12,431 · 2008 6,095 · 2009 1,513

US sales total153,026

AssemblyAM General, Mishawaka, Indiana (2002–2009); Avtotor, Kaliningrad, Russia (2006–2009)

Plant after the H2Sold to SF Motors, an electric-vehicle maker, in 2017

H2 SUT2005–2009Sport Utility Truck: short bed, Midgate, outside spare

Victory Red Limited Edition2004A named limited edition that appears in Bring a Trailer results; production numbers not found

Black Chrome Limited Edition2009Sedona Metallic paint and interior with black-chrome trim and 20-in wheels. 1,000–1,300 were planned, but Wikipedia says only six were built and none went on sale to the public

PART 03

Buying one

What to pay, what to check, and how to tell a good one from a clone.

What they cost

H2s are still affordable, but clean, unmodified, low-mile trucks, especially 2008–09s, now bring real money. Owners say untouched late trucks are getting hard to find.

Project / high miles or modified$10k–16k

Driver$17k–27k

Excellent / low-mile, especially 2008–09$30k–62k

Based on 18 Bring a Trailer H2 sales, May–October 2026: from $10,500 for a 2004 to $61,500 for a 10,000-mile 2008. Supercharged trucks brought $26k–43k. Several others, including a 2008 bid to $31,000, didn't meet reserve. Prices move; checked October 2026. See live listings below.

What to check before you buy

01
Find out what the air suspension has been doingIf the rear compressor runs at every stop light, there's a leak somewhere and the compressor is cooking itself. One owner was quoted $2,250 for a GM compressor before labor. Many trucks have already been converted to coils, which owners say costs under $250 in parts. Check which you're buying and whether the onboard air hose still works.
02
Shake the front end35-inch tires wear out ball joints, tie rods, pitman and idler arms and hub bearings, even in normal driving. Owners list the front ball joints and tie-rod ends as weak points. Budget roughly $400 in parts for a front-end rebuild before labor, and more if the torsion bars have been cranked.
03
Listen for a clunk from the front diffThe front differential hangs on three rubber bushings that soften with age, oil and coolant leaks. A loose diff clunks over bumps. Owners replace them with Outfitter Design's UHMW kit; one paid $400 to have it installed.
04
Cycle every 4WD modeShift through 4HI, 4HI Lock and 4LO Lock, and lock the rear diff in 4LO. A SERVICE 4WD message or a slow shift points to the encoder motor, the dash buttons or wiring. A bang followed by no 4WD at all usually means the plastic shift fork inside the transfer case has broken.
05
Look up at the roof and the sunroofOwners keep naming water leaks from the roof clearance lights and the sunroof. Check the headliner, the carpet and the rear cargo area for stains or a musty smell.
06
Know which truck you want2008–09 trucks have the 6.2, the six-speed and a far better interior, and owners say they're better 'in every way'. They also use some parts specific to those years, and 2009s are rare. 2003–07 trucks are cheaper and have more junkyard parts. Owners call the 4L65-E four-speed the drivetrain's weak link.
07
Inspect the chassis, not the chromeDealers can detail out a lot, but not rock gouges in the frame and skid plates. Lifts, tires and wiring added by previous owners are common, so trace any extra switches or lights, and run the VIN for open recalls.

Take these to the test drive: get the free printable Hummer H2 inspection checklist →

Spotting the real thing

Every H2 is a GM-engineered, AM General-built truck, but 2008–09 trucks have a different engine, transmission, interior and some chassis parts. Many trucks have also been lifted, converted from air springs to coils or re-engined, so check what you're looking at.

ID
VINUS H2 VINs begin 5GR (for example 5GRGN23U73H135443, a 2003 sold on Bring a Trailer). The owner's manual says the 8th character is the engine code: U is the 6.0 VORTEC 6000 (2004 manual) and 8 is the 6.2 (2008 manual). The 10th character is the model year.
ID
2003–07 vs 2008–092008–09 trucks have larger grille openings, a bigger lower grille and silver-painted lower bumpers (earlier trucks' are black). Inside, the dash and gauges are new and a rotary dial replaces the 4WD push buttons.
ID
SUTThe pickup has a short bed, a power Midgate window and a folding Midgate, an outside swing-away spare, and extra taillights in the lower rear bumper.
ID
Options labelThe Service Parts Identification label in the glovebox lists the VIN, paint and every production option. Look for ZM6, the GM option code for the self-leveling rear air suspension.
ID
Parts that changed in 2008Front hub bearings differ between 2003–07 and 2008–09 trucks (Kryptonite lists separate parts). Owners say the transfer case input spline also changed, because the 6L80's output shaft differs from the four-speed's.

Recalls & service bulletins

Open recalls follow the VIN, not the model. Run yours through NHTSA before you buy, and ask the seller for dealer records showing recall work.

Check a VIN at NHTSA ↗

Notable recalls

Windshield wiper motor failure ↗2003 · NHTSA 02V283000Improperly manufactured wiper motors could fail, reducing visibility in bad weather.

Ignition key / shift lever override ↗2003 · NHTSA 03V075000Mechanical overrides let the key come out or the shifter leave Park in ways FMVSS 114 doesn't allow without a locking column.

Hydro-boost relief valve bore ↗2003–2004 · NHTSA 04V045000An out-of-spec relief valve bore in the Hydro-boost brake housing could fracture its O-ring seal, slightly increasing steering and brake effort.

Hydro-boost accumulator cracking ↗2004–2005 · NHTSA 05V043000The Bosch Hydro-boost pressure accumulator could crack and separate; fragments could injure people near the engine bay with the hood open.

Second-row center seat belt routing ↗2004–2005 · NHTSA 05V163000The center rear lap belt may not sit low across the hips; owner's manual guidance was updated.

Power steering hose ↗2006 · NHTSA 05V455000An out-of-spec hose could fracture at full lock while braking, losing power steering and, with Hydro-boost, power brake assist.

Tire and loading label ↗2006 · NHTSA 05V552000Labels listed an incorrect vehicle capacity weight (FMVSS 110).

ABS wheel-speed sensor wiring ↗2008 · NHTSA 07V373000The front or rear ABS sensor harness wires may be reversed, which can lengthen stopping distances.

Heated washer fluid module (first campaign) ↗2006–2008 · NHTSA 08V441000A short on the washer-heater circuit board could overheat its ground wire; the fix added a fuse.

Water in the wiper motor module ↗2003 · NHTSA 08V456000On 13,358 model-year 2003 H2s, water could get into the wiper motor module and make the wipers intermittent or stop them working.

Heated washer fluid module (second campaign) ↗2006–2009 · NHTSA 10V240000New thermal incidents after the 2008 fix; the heated washer module could melt or catch fire.

Fabtech aftermarket pitman arms ↗2003–2006 (aftermarket part) · NHTSA 06E010000An equipment recall for Fabtech pitman arms FTS71000 and FTS71001: the internal pin can shear and cause total loss of steering. Check any lifted truck that has them.

The one you’ll own someday

For sale now

2003–2009 · USHummer H2 (all)

AutoTempest ↗Bring a Trailer ↗

2003–2007 · US6.0 LQ4, four-speed

AutoTempest ↗Bring a Trailer ↗

2008–2009 · US6.2 L92, six-speed

AutoTempest ↗Bring a Trailer ↗

2005–2009 · USH2 SUT pickup

AutoTempest ↗Bring a Trailer ↗

PART 04

Owning one

Baseline service, the repairs you’ll actually do, and where the manuals live.

Post-purchase baseline

After you buy it

Most H2s are now 17 to 23 years old, and few were serviced off-road. Treat every gear oil as unknown. The rear diff carries the E-locker, the transfer case is easy to neglect, and the front end needs grease. Fluids changed in 2008: the owner's manual lists DEXRON-III for the transmission and transfer case on a 2004, and DEXRON-VI on a 2008.

All Hummer H2 specs, fluids and service intervals on one printable page →

Engine oil & filterSAE 5W-30 meeting GM6094M · 6.0 qt (5.7 L) with filterWhen the oil-life monitor says so, and at least once a year

The 2004 manual lists the ACDelco PF44 filter (GM 25010633). The 2008 manual lists the PF48 (GM 89017524).

Parts

Oil filter (catalog, 2005 H2)RockAuto ↗

Oil filter (catalog, 2008 H2)RockAuto ↗

Search engine oil & filter for the Hummer H2Amazon ↗

Engine air filter & cabin filterGM 88944151 (2004 manual) · ACDelco A2948C / GM 10389652 (2008 manual)Inspect at every oil change; replace per the manual's schedule

Dusty trails clog it quickly. Check it after any desert trip.

Parts

Air filter (catalog, 2005 H2)RockAuto ↗

Cabin air filter (catalog, 2005 H2)RockAuto ↗

Search engine air filter & cabin filter for the Hummer H2Amazon ↗

Spark plugs & wiresACDelco 41-985 (GM 12571164) · gap 0.040 in (1.01 mm)Per the owner's manual schedule confirm in manual; do them now if there are no receipts

The same plug is listed for the 6.0 and the 6.2. Inspect the wires when you change the plugs, as the manual says.

Parts

Spark plugs (catalog, 2005 H2)RockAuto ↗

Spark plug wires (catalog, 2005 H2)RockAuto ↗

Search spark plugs & wires for the Hummer H2Amazon ↗

CoolantDEX-COOL 50/50 · 13.0 qt (2004 manual); 16.7 qt SUV / 15.4 qt SUT (2008 manual)5 years or 150,000 mi, whichever first

The manual warns that other coolants can corrode the radiator and heater core. One forum owner changes it every three years to protect the aluminum.

Parts

Coolant (catalog, 2005 H2)RockAuto ↗

Thermostat (catalog, 2005 H2)RockAuto ↗

Search coolant for the Hummer H2Amazon ↗

Automatic transmission fluid & filterDEXRON-III (4L65-E, 2003–07) · DEXRON-VI (6L80, 2008–09) · 6.0 qt with pan removal and filter (2008 manual)Fluid and filter on the severe-service schedule if you tow, run hills or sit in hot traffic

Do a pan drop and filter change rather than a flush. Owners call the four-speed the weak link, so treat its fluid as cheap insurance.

Parts

Transmission filter (catalog, 2005 H2)RockAuto ↗

Transmission fluid (catalog, 2008 H2)RockAuto ↗

Search automatic transmission fluid & filter for the Hummer H2Amazon ↗

Transfer case (BW 44-84)DEXRON-III (2004 manual) · DEXRON-VI (2008 manual) · 1.5 qt (1.4 L)Per the manual's mileage schedule; more often if you wade or tow

Fill to just below the fill hole. The manual also says to check that the transfer-case vent hose isn't kinked. Loosen the fill plug before you open the drain.

Parts

Transfer case fluid (catalog, 2005 H2)RockAuto ↗

Transfer case vent (catalog, 2005 H2)RockAuto ↗

Search transfer case (bw 44-84) for the Hummer H2Amazon ↗

Front & rear differentialsSAE 75W-90 synthetic meeting GM 9986115 (GM 12378261 in the 2004 manual, 89021677 in 2008)At purchase, then after any deep water crossing

Owners report the front takes about 2 quarts and the rear about 3. Many run Mobil 1 75W-90 synthetic. A forum owner warns that conventional 85W-90 can make the front diff stick and dart on cold mornings.

Parts

Gear oil (catalog, 2005 H2)RockAuto ↗

Differential cover gasket (catalog, 2005 H2)RockAuto ↗

Search front & rear differentials for the Hummer H2Amazon ↗

Chassis greaseNLGI #2 chassis lubricant (GM 12377985)At every oil change

Grease the front suspension, ball joints and steering linkage, but not the ball joints below 10°F (-12°C), per the manual. Dealers don't always do it: one was told the joints were sealed. The front propshaft spline takes GM spline lubricant 12345879.

Parts

Idler arm grease hose (catalog, 2005 H2)RockAuto ↗

Search chassis grease for the Hummer H2Amazon ↗

Power steering fluidGM power steering fluid 89021184Check at every oil change; flush if dark

The H2 uses Hydro-boost brakes, so the power steering pump also powers the brake booster. NHTSA's 05V455000 recall notes that losing steering fluid can also mean losing power brakes.

Parts

Power steering fluid (catalog, 2005 H2)RockAuto ↗

Search power steering fluid for the Hummer H2Amazon ↗

Brake fluidDOT 3 (Delco Supreme 11 or equivalent)Flush at purchase if there's no record

A 6,400-pound truck on big tires needs good brakes. Car and Driver measured 244 ft from 70 mph on a stock 2003.

Parts

Brake fluid (catalog, 2005 H2)RockAuto ↗

Search brake fluid for the Hummer H2Amazon ↗

Fuel filterACDelco GF626 (GM 25121792) in the 2004 manual's parts listAt purchase if there's no record confirm in manual

The 2008 manual's maintenance parts list doesn't include a separate fuel filter, so check whether your year has one.

Parts

Fuel filter (catalog, 2005 H2)RockAuto ↗

Search fuel filter for the Hummer H2Amazon ↗

Drive belt & hosesSerpentine belt; inspect the cooling hosesInspect per the manual's schedule; replace when cracked

The manual recommends a yearly pressure test of the cooling system and cap.

Parts

Serpentine belt (catalog, 2005 H2)RockAuto ↗

Search drive belt & hoses for the Hummer H2Amazon ↗

Rear air suspension (if fitted)Compressor, two height sensors, two air springsCheck at purchase

Listen for the compressor running constantly and look for a rear that sags overnight, both signs of a leak. The owner's manual says leveling stops with any door open.

Parts

Ride height sensor (catalog, 2005 H2)RockAuto ↗

Search rear air suspension (if fitted) for the Hummer H2Amazon ↗

BatteryGroup 79 stock, according to ownersTest at purchase

A weak battery causes odd 4WD and electrical faults, and the rear locker disengages when battery voltage is low (owner's manual). Owners say other group sizes fit if you leave out the plastic battery box.

Parts

Search battery for the Hummer H2Amazon ↗

For the hands-on owner

Common repairs

The jobs owners actually end up doing, rated for a competent home mechanic with a decent tool kit. Always confirm torque figures, fluids and procedures against the factory service manual for your VIN, and work safely — support the truck on stands, never just a jack. You do this work at your own risk; see the disclaimer. Some parts links are affiliate links.

Hunting a used or discontinued part? Search eBay Motors for AM General Hummer H2 parts →

Front differential bushings →

DIFFICULTY · 3 / 5TIME · ≈ Half a day (much less if the diff is already out for gears)SHOP COST · One owner: $400 to install, about $600 all in with the kit

SYMPTOMSA clunk from the front over bumps, or the diff visibly rocking when someone shifts between Park, Reverse and Drive. Oil or coolant dripping onto the old rubber bushings speeds up the wear.

THE FIXSupport the front diff, disconnect the front driveshaft and CV axles as needed, and unbolt the three mounts: the crossmember bushing, the top mount and the side mount. Press out the old rubber and fit all three replacement bushings, since Outfitter Design sells them only as a kit so the mounts share the same hardness. Fix the oil leaks first if you can; one shop wouldn't install new bushings until the leaks were repaired.

TOOLS & PARTSJack and transmission or diff jack · press or bushing tools · torque wrench. Outfitter Design's kit is UHMW (one crossmember bushing plus top and side mount bushings with steel sleeves).

WHERE TO BUY PARTSH2 front differential bushing kit (UHMW, all three mounts) · Outfitter Design ↗Amazon ↗Front differential seals (catalog, 2005 H2) · RockAuto ↗

Rear air suspension: compressor, air springs or coil conversion →

DIFFICULTY · 2 / 5TIME · ≈ 2–4 hours for a coil conversionSHOP COST · One owner was quoted $2,250 for a GM compressor before labor; another converted to coils for under $250 in parts

SYMPTOMSSERVICE AIR SUSPENSION message, the rear sagging overnight, or a compressor that runs constantly. The owner's manual says leveling pauses with any door open, so close everything before you diagnose it.

THE FIXTo repair it, find the leak first (lines, fittings or the air springs) before replacing the compressor. Owners say later dual-stage compressors are less likely to overheat, and switching to one needs two new hoses. To convert, support the frame, lower the axle (one owner didn't need to remove the shocks), remove the air springs and fit coil springs with upper and lower isolators.

TOOLS & PARTSJack and stands · basic sockets · soapy water for leak checks. Fabtech lists H2 coil-spring and air-bag lift options.

WHERE TO BUY PARTSAir suspension compressor (catalog, 2005 H2) · RockAuto ↗Rear air springs (catalog, 2005 H2) · RockAuto ↗Coil springs (catalog, 2005 H2) · RockAuto ↗H2 2003–09 OEM air bag lift parts · Fabtech ↗Amazon ↗

Steering linkage rebuild: tie rods, pitman arm, idler arm and support →

DIFFICULTY · 3 / 5TIME · ≈ Half a day plus an alignmentSHOP COST · About $400 in parts for one owner's front end, not including shocks

SYMPTOMSWander, a steering wheel that won't center, clunks over bumps and uneven tire wear. Lifted trucks and cranked torsion bars make it worse: one owner says parts wore out 'five times faster'.

THE FIXSeparate the tie-rod ends, pitman arm and idler arm with a puller, count the turns on the tie-rod sleeves to keep a rough toe setting, and replace the worn parts. Owners recommend heavier tie rods and an idler and pitman support kit if you run 37s. Grease every fitting afterwards. The idler support's fitting can't be reached without removing it, so a grease-relocation kit helps. Get the truck aligned.

TOOLS & PARTSPitman arm puller · tie-rod separator · grease gun · torque wrench. The H2 shares its steering with 2001–10 GM HD trucks.

WHERE TO BUY PARTSKryptonite Death Grip idler support (fits Hummer H2) · Kryptonite ↗Amazon ↗Kryptonite Death Grip pitman arm 2001–2010 · Kryptonite ↗Amazon ↗Kryptonite Series tie rods 2001–2010 · Kryptonite ↗Amazon ↗Forged pitman/idler arm support kit, 2001–10 GM 2500/3500 (confirm H2 fit) · Cognito Motorsports ↗Amazon ↗

Front lower ball joints →

DIFFICULTY · 3 / 5TIME · ≈ 3–6 hours (one shop quoted 6 hours for both sides)SHOP COST · $720 with parts at one shop; ball joints $20–40 each for a DIYer

SYMPTOMSAn alignment that won't hold, play at the bottom of the knuckle when you rock the tire top to bottom, and clunks. In one owner's 2006 the upper ball joint pulled out of the control arm while driving.

THE FIXUnload the torsion bar first. Then remove the wheel, brake caliper and rotor, separate the lower ball joint from the knuckle, and press the old joint out of the control arm with a rented ball-joint press. One owner needed a torch and 'a lot of patience' with a breaker bar. Press in the new joint, torque it, grease it (the manual says not below 10°F) and get an alignment.

TOOLS & PARTSBall-joint press (rentable) · torsion-bar unloading tool · torch · breaker bar · torque wrench.

WHERE TO BUY PARTSKryptonite lower ball joint (2002–09 H2, 8-lug) · Kryptonite ↗Amazon ↗Ball joints (catalog, 2005 H2) · RockAuto ↗

Front wheel hub bearing →

DIFFICULTY · 2 / 5TIME · ≈ 1–2 hours per sideSHOP COST · Parts plus labor

SYMPTOMSA growl that changes with speed or when you weave, play at the wheel, or ABS, traction control and SERVICE 4WD warnings when a failing hub damages the wheel-speed sensor. One owner running 37s is on their sixth set.

THE FIXRemove the wheel, caliper, rotor and CV axle nut, unplug the ABS sensor, then unbolt the hub from the knuckle and fit the new unit. Owners prefer Timken, which they say is the OE supplier, or the ACDelco FW314. Torque the axle nut to the factory figure; owners disagree about the number, so check the service manual.

TOOLS & PARTSLarge axle-nut socket · breaker bar · hub puller or a hammer for seized hubs · torque wrench.

WHERE TO BUY PARTSKryptonite wheel bearing (fits 2003–07 H2) · Kryptonite ↗Amazon ↗Kryptonite wheel bearing (fits 2008–09 H2) · Kryptonite ↗Amazon ↗Wheel bearing & hub (catalog, 2005 H2) · RockAuto ↗

Transfer case won't shift: encoder motor or shift fork →

DIFFICULTY · 3 / 5TIME · ≈ 1 hour for the motor, an afternoon to drop the case for a forkSHOP COST · Owners quote about $200–400 for an encoder motor

SYMPTOMSA SERVICE 4WD message, mode lights that keep flashing, shifts that take minutes, or a bang followed by no 4HI or 4LO at all.

THE FIXScan the codes first. Clean or check the dash buttons, then check the encoder motor on the transfer case and its wiring. Owners warn that remanufactured and non-OEM motors are 'rubbish'. One owner says the usual failure is the contact ring inside the encoder, sold separately. If the case banged and stopped working, the plastic shift fork has probably broken: drop the transfer case, fit an aluminum fork and refill with fresh fluid.

TOOLS & PARTSScan tool that reads transfer-case codes · transmission jack · seal kit · fluid pump.

WHERE TO BUY PARTSTransfer case motor / encoder (catalog, 2005 H2) · RockAuto ↗Transfer case shift fork (catalog, 2005 H2) · RockAuto ↗Transfer case control module (catalog, 2005 H2) · RockAuto ↗

Radiator replacement →

DIFFICULTY · 2 / 5TIME · ≈ 2–4 hoursSHOP COST · OEM about $300–325; aftermarket $130–190 (owner reports)

SYMPTOMSA coolant puddle at the front, a crack in a plastic tank, rising temperatures when towing.

THE FIXDrain the coolant, then disconnect the hoses and the transmission cooler lines. Their retention clips are the worst part of the job, and one owner drove for a month with a clip not fully seated. Lift the radiator out without bending the fins; the front-hinged hood makes this awkward alone. Replace the lower hose while you're there, then refill with DEX-COOL and bleed the system.

TOOLS & PARTSDrain pan · trans-line clip tool · something solid to stand on in the engine bay.

WHERE TO BUY PARTSRadiator (catalog, 2005 H2) · RockAuto ↗Radiator hoses (catalog, 2005 H2) · RockAuto ↗Coolant (catalog, 2005 H2) · RockAuto ↗

Heater core quick-connect leak →

DIFFICULTY · 1 / 5TIME · ≈ 1 hourSHOP COST · A fitting and a coolant top-up

SYMPTOMSCoolant running down the passenger side of the transmission bell housing while the passenger floor stays dry, and the engine running warm with the heater on.

THE FIXBefore you condemn the heater core, check the quick-connect fittings at the core. Slide a release tool of the right size up into the fitting to free the clips, twist the fitting off, fit the new one, push the hose on, refit the clip and top up the coolant.

TOOLS & PARTSQuick-connect release tool set · coolant.

WHERE TO BUY PARTSHeater hose connector (catalog, 2005 H2) · RockAuto ↗Heater hose (catalog, 2005 H2) · RockAuto ↗

Manuals & documentation

Helm Inc. — GM factory service manuals and owner's literature ↗The publications supplier the H2 owner's manual itself names for factory service manuals ACDelco TDS — GM service information subscription ↗GM's official paid portal for service information on older GM vehicles

Hummer H2 owner's manuals (GM, 2003–2009)The capacities, fluids, maintenance schedule, 4WD and locker sections are worth having; buy a printed original or a Helm reprint

Asked on every forum

Hummer H2 questions, answered

What's the biggest tire I can fit without a lift?

Owners agree on 37x12.50R17 on stock wheels, or wheels with the same offset. One owner runs Cooper STTs at stock height with a slight torsion-bar crank and doesn't rub at full stuff, apart from a light scrub on the sway bar at full lock, which the stock 35s do too. 37x14.50s didn't fit. Wider tires or different offsets need a lift, spacers or both.

SOURCE · HUMMER4X4OFFROAD

Is it really just a Tahoe underneath?

Partly. Car and Driver reported a Suburban frame cut down by 7.2 inches, a 2500-series front suspension and a Suburban five-link rear. The body, transfer-case calibration, rear E-locker, skid plates and angles are H2-specific, and AM General built the trucks in Mishawaka. Parts for the engine and front end cross over with GM trucks; body and trim parts mostly don't.

SOURCE · CAR AND DRIVER · OWNERS

What fuel economy does it get?

No official rating exists, because its 8,600-lb GVWR exempted it from EPA testing. Magazines measured 9 to 10.8 mpg. Owners on 37s report about 10.5 mpg on the stock 4.10 gears, and one got 12.5 after regearing to 4.56.

SOURCE · WIKIPEDIA · HUMMER4X4OFFROAD

Does it have lockers?

Every H2 has a lockable center differential and an Eaton ELocker in the rear axle. The rear locker only works in 4LO Lock, engages below 2 mph and drops out above 20 mph. There's no front locker from the factory; one owner added an Eaton E-locker to the front diff while regearing.

SOURCE · OWNER'S MANUAL · OWNERS

Which years should I buy?

If budget allows, 2008–09 for the 6.2, the six-speed and the much better interior; owners say they're better in every way. They're also the rarest and most expensive, and some of their parts are specific to those years. Among 2003–07 trucks, one owner would pick a mid-2005 to 2007 truck over a 2003 for the stronger front diff and better build.

SOURCE · HUMMER4X4OFFROAD

Should I keep the air suspension?

Opinion is split. Owners who tow love being able to raise and lower the rear, and the onboard air hose. Others have replaced compressors more than once at around $2,000 installed and switched to coils, saying the ride hardly changed. If the compressor runs constantly, find the leak before replacing it.

SOURCE · HUMMER4X4OFFROAD

How much can it tow?

GM's 2003 spec sheet said 7,000 lb. GM's 2008 announcement said the new powertrain raised capacity from 6,500 to 8,000 lb. Use tow/haul mode, and check your door sticker and hitch rating.

SOURCE · GM VIA OFF-ROAD.COM · ROCKCRAWLER

Do I need to regear for 37s?

Owners say the stock 4.10s with 37s feel gutless on the highway and the transmission keeps hunting for gears. 4.56 restores roughly stock feel on 37s; 4.88 suits 38s or bigger and towing. Expect to retune the speedometer and shift points afterwards. Owners were quoted $1,900 to $4,800 for both axles.

SOURCE · HUMMER4X4OFFROAD

Can I level it with the torsion bars?

Yes. Crank the stock keys or fit GM's re-indexed 'green' keys; one owner gained about an inch with the green keys alone. Owners warn that cranked torsion bars ride harsher and wear tie rods, pitman and idler arms much faster, and the extra height leaves a gap above the bump stops.

SOURCE · HUMMER4X4OFFROAD

What does 'SERVICE 4WD' mean?

The transfer-case control system has a fault. Common causes are sticking dash buttons or a mode dial, a failing encoder motor on the transfer case, damaged wiring, or a bad wheel-speed sensor or hub bearing. Have it scanned with a proper tool, because a cheap code reader won't show the module's codes.

SOURCE · OWNER'S MANUAL · OWNERS

How do I flat-tow it behind an RV?

The transfer case has a NEUTRAL position for towing the H2 with all four wheels on the ground; the owner's manual explains the procedure. Set the parking brake before you select NEUTRAL, because the truck can roll even with the transmission in Park.

SOURCE · OWNER'S MANUAL

PART 05

Building one

Who makes the good stuff, where owners gather, and who to watch.

Common modifications & who does them

LEVELING & LIFTThe H2 sits nose-down from the factory. A leveling kit or torsion-bar keys raise the front for 37s. Owners run 40s on 6-inch lifts with 4.5-inch-backspace wheels, but suspension lifts drop the torsion bars and crossmember lower under the truck.

Kryptonite — Stage 2 leveling kit (2002–09 H2) ↗Fabtech — H2 coil-spring lift parts ↗Rancho — H2 shocks ↗

STEERING & FRONT END35s and 37s eat the stock linkage and ball joints. Heavier tie rods, a pitman and idler support and better ball joints are the usual first spend.

Kryptonite — H2 front-end parts ↗Kryptonite — upper control arms (2001–10 GM HD) ↗Cognito Motorsports — 2001–10 GM HD steering ↗

FRONT DIFF MOUNTSSolid UHMW bushings stop the front diff rocking in its mounts, and owners say the front end feels 'ten years newer' after the swap.

Outfitter Design — H2 front differential bushing kit ↗

GEARS & LOCKERSRegear to 4.56 for 37s or 4.88 for 38s and up, and add a front locker while the diff is apart. Retune the computer afterwards.

RockAuto — H2 ring & pinion and install kits ↗

ARMOR & BUMPERSOne owner says a stock-height H2 'hits everything on the trail with the front skid'. Steel bumpers and sliders take the abuse instead, and leveling the truck helps.

Road Armor — Hummer bumpers ↗