4.8L Isuzu 4HE1 Turbodiesel

Isuzu 4.8L I-4 Diesel Specs & Information

Isuzu introduced the 4HE1 turbodiesel to their NPQ and NPR cab-over truck models for the 1999 model year, in addition to several cab-over models from General Motors. The engine platform was ultimately replaced for the 2005 model year in favor of a more powerful and emissions friendly 5.2L, the Isuzu 4HK1. The inline 4 cylinder 4HE1 features a robust cast iron engine block with dry cylinder liners, cast iron cylinder head, and gear driven overhead camshaft.

The 4.8L was rated at a peak 175 horsepower in automatic transmission applications and 142 horsepower in applications with a manual transmission. The engine is notable for its low end performance; although the automatic transmission equipped engine produces peak torque at 2,000 RPM, the engine's nearly 5 inch stroke and undersquare bore-to-stroke ratio provide considerable torque at low engine speeds. Transmission options were a Isuzu MXA-5C 5 speed manual, Isuzu MZZ 6 speed manual, or an Aisin-Warner 450-43LE 4 speed automatic. While both the 6 speed manual and 4 speed automatic transmissions feature overdrive, the 5 speed manual transmission's final gear was direct drive (1:1).

4.8L Isuzu 4HE1 Specs

Engine:

Isuzu 4.8L 4HE1-TC

Manufacturer:

Isuzu Motors Ltd.

Applications:

1999 - 2004 Isuzu NPR
1999 - 2004 Isuzu NQR
1999 - 2004 GMC W3500, W4500, W5500
1998 - 2001 Chevrolet W4/W5 Tiltmaster

Type:

4 Stroke diesel

Configuration:

Inline 4 cylinder (I-4/L-4)

Displacement:

4.75 liters, 289.96 CID (nominal 4.8 liter/290 CID displacement)

Firing Order:

1 - 3 - 4 - 2

Engine Block:

Cast iron

Cylinder Head:

Cast iron

Cylinder Liner Type:

Dry

Compression Ratio:

17.3 : 1

Cylinder Bore:

4.330 inches (110 mm)

Cylinder Stroke:

4.921 inches (125 mm)

Valvetrain:

Single gear driven overhead camshaft (OHC), 2 valves per cylinder

Valve Clearance:

Intake

0.4 mm

Exhaust

0.4 mm

Injection:

Direct injection

Aspiration:

Turbocharged & intercooled

Engine Oil Capacity:

14.5 U.S. quarts (13 liters)

Engine Oil Viscosity:

Varies by ambient operating temperature; see chart below

Rated Horsepower*:

Manual transmission

142 HP @ 2,800 RPM

Automatic transmission

175 HP @ 2,700 RPM

Rated Torque*:

Manual transmission

275 lb-ft @ 1,300 RPM

Automatic transmission

347 lb-ft @ 2,000 RPM

Max Engine Speed:

2800 - 2900 RPM (max RPM @ full load)

*NPR, NPQ, and GM W4500/W5500 gross horsepower ratings

 

Transmission Options & Ratios (NPQ/NPR Models)

 

1st

2nd

3rd

4th

5th

6th

R

Remarks

Isuzu MXA-5C

6.020

3.626

2.017

1.367

1.00

---

6.030

5 speed manual, synchronized, direct drive

Isuzu MZZ-6F

6.369

3.767

1.966

1.355

1.00

0.782

6.369

6 speed manual, synchronized, overdrive

Aisin Warner 450-43LE

3.018

1.548

1.000

0.703

---

---

2.678

4 speed automatic, overdrive

 

Isuzu 4.8L 4HE1 Maintenance Schedule

Service Procedure

Service Interval

Notes

Replace engine air filter

Every 26,000 miles/12 months

Check condition of air filter at oil change intervals & replace as necessary, or every 26,000 mi/12 mo

Replace engine oil & oil filter

Every 6,500 miles/12 months

Engine oil level should be checked between oil change intervals

Replace fuel filter

Every 13,000 miles/12 months

Replace fuel filter & drain fuel water separator

Replace engine drive belt

104,000 miles

Check condition of drive belt at oil change intervals & replace as necessary; replace regardless at ~100,000 miles

Drain/replace engine coolant

Every 26,000 miles/24 months

Drain/refill cooling system and inspect condition of coolant hoses; replace as necessary

Adjust valve lash

Every 52,000 miles

Set intake & exhaust valve lash to 0.016 in (0.4 mm)

Replace automatic transmission filter & fluid

Every 26,000 miles/12 months

Replace internal and auxiliary transmission filters as applicable

Replace manual transmission oil

Every 19,500 miles/12 months

Drain/refill transmission

Replace rear differential oil

Every 26,000 miles/24 months

Drain/refill differential

Isuzu 4.8L 4HE1 Oil Viscosity Chart

Oil Viscosity

Ambient Temperature Range

SAE 10W-30

-20° F to 90° F

SAE 10W-40

-20° F +

SAE 15W-40

0° F +

SAE 15W-50

0° F +

SAE 20W-40

0° F +

SAE 20W-50

0° F +

SAE 10W

-20° F to 32° F

SAE 20W

0° F to 60° F

SAE 30W

32° F to 90° F

SAE 40W

75° F +

SAE 50W

75° F +