Specs, fluids & service · 1992–2006
AM General Hummer H1 specs, fluids and service intervals
The numbers you need in the garage, on one page: spec sheet, capacities and service intervals, wheels and tires, and the parts to order. Sourced from owners, specialists and the factory; tags marked confirm in manual haven't been checked against a factory source yet.
Spec sheet
| BUILT | Mishawaka, Indiana · 1992 – June 2006 |
|---|---|
| PRODUCTION | 11,818, including 729 Alphas |
| BASED ON | AM General M998 HMMWV |
| CHASSIS | Steel box-section ladder frame, 5 crossmembers |
| WHEELBASE / WIDTH | 130 in / 86.5 in |
| GROUND CLEARANCE | 16 in |
| ENGINES | GM 6.2 & 6.5 diesel · 6.5 TD · 5.7 V8 gas · 6.6 Duramax LLY (2006) |
| TRANSMISSIONS | 3L80 3-spd · 4L80-E 4-spd · Allison 1000 5-spd (2006) |
| TRANSFER CASE | New Venture NVG 242, full-time |
| AXLE RATIO | 2.73:1 to 1997 · 2.56:1 from 1998 |
| GEARED HUBS | 1.92:1 portal reduction |
| FORDING | 30 in diesel · 24 in gas |
By year
| YEARS | PLATFORM | ENGINE | OUTPUT | NOTES |
|---|---|---|---|---|
| 1992–1993 | H1 · 6.2 diesel | GM 6.2 V8 diesel (mechanical injection) | 150 hp | 3L80 three-speed automatic, 25-gal tank, batteries under the passenger seat. No overdrive; 316 built for 1992. |
| 1994–1998 | H1 · 6.5 diesel | GM 6.5 V8 diesel, naturally aspirated | 170 hp / 290 lb-ft | Electronic controls and the 4L80-E four-speed from 1994. The non-turbo diesel was dropped for 1999. |
| 1995–1996 | H1 · gas | GM 5.7 L05 V8, throttle-body injection | 190 hp / 300 lb-ft | 23-gal tank and 24-in fording depth. Dropped during 1996. |
| 1996–2003 | H1 · 6.5 turbo diesel | GM (from 2001 AM General) 6.5 V8 turbo diesel | 190 hp / 385 lb-ft (1996); 195 hp / 430 lb-ft (1997 on) | Second fuel tank from 1996. Blocks from 1996 to early 1999 are at risk of a crack at the No. 8 cylinder. |
| 2004 | H1 · Optimizer | 6.5 V8 turbo diesel with Caterpillar-built ECM | 205 hp / 440 lb-ft | Changed to meet emissions rules. New interior; optional front and rear Eaton lockers. There was no 2005 model year. |
| 2006 | H1 Alpha | GM 6.6 Duramax LLY V8 turbo diesel | 300 hp / 520 lb-ft | Allison 1000 five-speed, 2-in body lift, 51 gal of fuel, open top or wagon only. 729 built. |
Fluids, capacities & service intervals
Assume the last owner skipped things. H1s changed constantly in production, so decode the VIN first: the fourth digit is the engine and the fifth the transmission. AM General's HUMMER Recommended Maintenance Schedule (#0574480) runs on a 3,000-mile cycle with inspection groups A, B and C, and a truck that's over 24,000 miles and behind on service should start at the 12,000-mile service.
| ITEM | SPEC / CAPACITY | INTERVAL | NOTES & PARTS |
|---|---|---|---|
| Engine oil & filter | Diesel-rated oil (Flash Off-Road uses Shell Rotella T) · 6.5 TD ≈ 7.5 qt, 6.5 NA ≈ 8 qt with filter | Every 3,000 mi on the factory schedule | Flash Off-Road uses a Delco PF-1218 filter. Diesel oil turns black almost at once, which is normal.Oil filter, 1998 H1 6.5 TD (catalog) · RockAuto ↗Engine oil (catalog) · RockAuto ↗ |
| Chassis grease | NLGI-LB chassis grease · 26–27 fittings | Every oil change | Don't forget the two steering-column fittings behind the kick panel and the one in the steering shaft U-joint under the hood. Go easy on the front driveshaft slip joint or you'll pop the cap. |
| Fuel filter (diesel) | Replace element; drain water from the filter bowl | Element every 6,000 mi on the factory schedule; drain as needed | Water reaching the injectors destroys them. Carry a spare filter off-road.Fuel filter, 1998 H1 6.5 TD (catalog) · RockAuto ↗ |
| Air filter | Factory-type paper element | Clean or replace every 6,000 mi | Flash Off-Road advises against K&N filters on H1s. The geared hubs and transfer case vent into the air cleaner, so keep the housing sealed.Air filter, 1998 H1 6.5 TD (catalog) · RockAuto ↗ |
| Coolant & thermostats | Coolant type confirm in manual · ≈25 L (26 US qt) system on the 6.5 diesels (Liqui Moly lookup) · two 195°F thermostats, GM 12559336 | Flush every 12,000 mi on the factory schedule | Flash Off-Road weighs nitrite-protected diesel coolants such as Fleet Charge against regular antifreeze; its author went back to regular antifreeze, citing the 6.5's thick, unsleeved cylinder walls. It also reports a batch of bad thermostats in the supply chain around 2000. On a turbo diesel, run the No. 8 cylinder pressure check at the same time.Thermostat, 1998 H1 6.5 TD (catalog) · RockAuto ↗Coolant (catalog) · RockAuto ↗ |
| Automatic transmission | Dexron III per Flash Off-Road · Allison 1000 fluid on the Alpha confirm in manual | Service every 12,000 mi on the factory schedule | There are three different filter and pickup designs depending on the year and pan depth, so match the filter. Flash Off-Road flushes every 35,000 mi or so and changes the filter after 50,000.Transmission filter, 1998 H1 6.5 TD (catalog) · RockAuto ↗Transmission fluid (catalog) · RockAuto ↗ |
| Transfer case (NVG 242) | Dexron III; Flash Off-Road recommends synthetic Dexron | Service every 12,000 mi on the factory schedule | If it's overfull or pours out when you open the fill plug, the cooler loop is leaking ('the vampire', AM General campaign R0101).Transfer case fluid (catalog) · RockAuto ↗ |
| Differentials | GL-5 gear oil · trucks with Eaton E-lockers need AM General synthetic 75W-90 with friction modifier · ≈1.9 L (2.0 US qt) per differential on the 6.5 diesels (Liqui Moly lookup) | Check level and condition at every Group A inspection | Tags on the covers give the ratio and Torsen type. 1998 and later trucks use 2.56:1, earlier ones 2.73:1.Gear oil (catalog) · RockAuto ↗ |
| Geared hubs | GL-5 80W-90 or 75W-90 · about 1/2 qt per hub | Check at every Group A inspection; change after deep water | Milky oil means water got in through a seal or a cracked vent line. Drain and fill plugs need only 8–13 lb-ft.Gear oil (catalog) · RockAuto ↗ |
| Brake fluid | DOT 5 silicone on 1992–1998 trucks; DOT 3 on 1999-on trucks with ABS (Flash Off-Road) | Flush at purchase, then per the manual | Never mix the two: silicone DOT 5 and glycol DOT 3 don't blend, and Flash Off-Road says two colors in the reservoir mean someone has. The 1999–2000 trucks had a recall for chafing master-cylinder-to-ABS lines. Check the brake lines for corrosion.Brake fluid (catalog) · RockAuto ↗ |
| Steering & front end | Idler arm, pitman arm, tie rods, ball joints | Inspect every 3,000 mi; alignment check every 12,000 | Flash Off-Road says aligning a pre-'97.5 truck means shimming the upper A-arms and can take 6–8 hours; eccentric washers made camber adjustable from 1998.Ball joint, 1998 H1 6.5 TD (catalog) · RockAuto ↗ |
| Halfshaft bolts & boots | 57 lb-ft with Nord-Lock washer pairs | Inspect bolts every 3,000 mi and boots every 6,000 mi | The factory figure was originally 48 lb-ft; Flash Off-Road gives 57 lb-ft as the current recommendation.CV joint boot (catalog) · RockAuto ↗ |
| CTIS function | Inflate and deflate test, front, rear and both | Every Group A inspection | Flash Off-Road suggests 30–37 psi cold on the road, depending on the tire.Stainless Steel Inboard CTIS Lines – full kit · Predator Inc ↗ |
| Serpentine belt & batteries | Inspect the belt; check battery voltage and condition | Belt every 6,000 mi; batteries checked at 24,000 mi | Batteries moved under the hood in 1994; 1992–93 trucks keep them under the passenger seat. |
Capability
| Towing | 7,710 lb (3,497 kg) wagon · 8,050 lb (3,651 kg) open top 1999 turbo diesel, 10,300/10,800-lb GVWR (brochure); Edmunds gives 9,300 lb for an Alpha open top |
|---|---|
| GVWR | 10,300 or 10,800 lb 1999 brochure |
| Payload | 3,210 lb (1,456 kg) wagon · 3,550 lb (1,610 kg) open top 10,300-lb GVWR, 1999 brochure |
| Curb weight | 7,090 lb (3,216 kg) wagon · 6,750 lb (3,061 kg) open top 1999 turbo diesel |
| Fuel tank | 25 gal (95 L) + 17 gal (64 L) reserve 1996 on; 25 gal only before 1996 (23 gal on gas trucks); 51 gal on the Alpha |
| Ground clearance | 16 in (406 mm) |
| Approach / departure | 72° / 37.5° 47° approach with a winch (1999 brochure) |
| Grade / side slope | 60% / 40% |
| Wading depth | 30 in (762 mm) 24 in for the 1995–96 gas trucks (Flash Off-Road) |
| Turning radius | 26.5 ft (8.1 m) |
| Width / wheelbase / track | 86.5 in / 130 in / 71.6 in |
| Runflat range | 20 miles at 30 mph With the optional runflat inserts (1999 brochure) |
| 0–60 mph | 18.0 s (1999 turbo diesel) · 13.5 s (2006 Alpha) Brochure; Edmunds |
| Fuel economy | About 11.5 mpg city / 15 highway Real-world 1996 turbo diesel driven under 67 mph (Flash Off-Road); the gas trucks returned 7–11 |
Wheels & tires
| Factory tire | 37x12.50R16.5 LT load range D Goodyear Wrangler MT radial on 16.5-in wheels (1999 brochure) · 37x12.5R17 on 17-in aluminum wheels (offered from 2000; 16.5-in aluminum wheels discontinued by 2002) |
|---|---|
| Bolt pattern | 8x165.1 (8x6.5") |
| Center bore | About 4-3/4 in on the hub-centric factory one-piece steel wheel |
| Lug thread | 9/16-18 (7/8-in hex nut; a 22 mm socket fits) |
| Biggest tire · Stock | 38x15.5 |
| Biggest tire · 1 in (body) | 40 in (MT/R) |
| Biggest tire · 2 in (body) | 39.5 in |
| Biggest tire · 4 in (2 in suspension + 2 in body) | Up to 42 in |
Common Hummer H1 repairs
- Replace geared-hub output and spindle sealsDIFFICULTY 3 / 5
- Replace the idler and pitman armsDIFFICULTY 3 / 5
- Relocate the 6.5 TD's pump-mounted driver (PMD/FSD)DIFFICULTY 2 / 5
- Replace the fuel shutoff solenoidDIFFICULTY 1 / 5
- Find and fix a CTIS leakDIFFICULTY 2 / 5
- Rebuild or replace a halfshaftDIFFICULTY 3 / 5
- Replace inboard brake pads (and rotors)DIFFICULTY 3 / 5
- Test and replace glow plugsDIFFICULTY 2 / 5
Always confirm torque figures, fluids and capacities against the factory service manual for your VIN. See the disclaimer; some parts links are affiliate links.