Toyota 1HD-T

Toyota 1HD-TThe Toyota 1HD-T is a 4.20 l (4,164 cc, 254.1 cu-in) six cylinders, four-stroke cycle water-cooled turbocharged internal combustion diesel engine, manufactured by the Toyota Motor Corporation.

The 1HD-T engine has a cast-iron block with 94 mm (3.7 in) cylinder bores and a 100 mm (3.94 in) piston stroke. Compression ratio rating is 18.6:1. The motor has a cast iron cylinder head with a single overhead camshaft (SOHC) with two valves per cylinder; direct-injection design and Toyota CT26 turbocharger with a boost pressure of 0.48 bar.

The Toyota 1HD-T produced 167 PS (123 kW; 165 HP) at 3,600 rpm of maximum horsepower and 363 Nm (37.0 kg·m; 267.9 ft·lb) at 2,000 rpm of maximum torque.

The breakdown of the engine code is as follows:

  • 1 – 1nd generation engine
  • HD – Engine family
  • T – Turbocharged

General information

Engine Specifications
Engine code1HD-T
LayoutStraight-6, vertical
Fuel typeDiesel
Production1988-1995
Displacement4.2L, 4,164 cc (254.1 cu in)
Injection pumpMechanical
Power adderToyota CT26
Horsepower net 165 PS (121 KW; 162 HP) at 3,600 rpm
167 PS (123 KW; 165 HP) at 3,600 rpm
Torque output 360 Nm (36.7 kg·m; 265.7 ft·lb) at 1,800 rpm
363 Nm (37.0 kg·m; 267.9 ft·lb) at 2,000 rpm
Firing order1-4-2-6-3-5
Dimensions (L x H x W):
Weight

Cylinder block

The cylinder block is made of cast iron. The crankshaft is supported by 7 bearings on the inside of the crankcase. The crankshaft is integrated with 12 balance weights. The crankshaft bearing cap is of ladder-frame construction and is incorporated into the crankcase. The top of the cylinders is closed off by the cylinder head and the lower end of the cylinders becomes the crankcase, in which the crankshaft is installed.

Pistons are made of highly temperature-resistant aluminum alloy. As the 1 HD-T engine is the direct injection type, a deep combustion chamber has been provided. The first compression ring is made of steel and the second compression ring is made of cast iron. The oil ring is made of steel.

The cylinder bore is 94 mm (3.7 in), piston stroke is 100 mm (3.94 in) and compression ratio rating is 18.6:1.

Cylinder block
Cylinder block alloyCast iron
Compression ratio:18.6:1
Cylinder bore:94 mm (3.7 in)
Piston stroke:100 mm (3.94 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:7
Cylinder bore inner diameter:94.000-94.030 mm (3.7001-3.7019 in)
Piston skirt diameter93.845-94.855 mm (3.8947-3.8951 in)
Piston ring groove:First0.050-0.095 mm (0.0020-0.0037 in)
Second0.060-0.100 mm (0.0024-0.0039 in)
Oil0.030-0.070 mm (0.0012-0.0028 in)
Piston ring end gap:First0.270-0.540 mm (0.0106-0.0212 in)
Second0.400-0.620 mm (0.0157-0.0244 in)
Oil0.200-0.520 mm (0.0079 – 0.0204 in)
Piston pin outer diameter33.000-33.012 mm (1.2992-1.2997 in)
Piston pin bore diameter33.008-33.020 mm (1.2995-1.3000 in)
Crankshaft main journal diameter:66.994-67.004 mm (2.6375-2.6379 in)
Crankpin diameter:58.994-59.004 mm (2.3225-2.3230 in)
Crankshaft center distance:50.0 mm (1.9685 in)

Main bearing cap tightening procedure and torque specs:

  • Step 1: 103 Nm; 10.5 kg·m; 76 ft·lb
  • Step 2: Turn all bolts 90°

After securing bearing cap bolts, make sure crankshaft turns smoothly by hand.

Connecting rod bearing nut

  • Step 1: 37 Nm; 3.75 kg·m; 27 ft·lb
  • Step 2: Turn all bolts 90°

Crankshaft pulley bolt

  • 500 Nm; 50.0 kg·m; 369 ft·lb

Flywheel (M/T) or Drive plate (A/T) fixing bolts

  • 127 Nm; 13.0 kg·m; 94 ft·lb

Cylinder head

The cylinder head is made of cast iron with a cross-flow type intake and exhaust layout. The camshaft journal part of the cylinder head has camshaft caps made of aluminum alloy and is made of cast iron on the cylinder head side. The camshaft is driven by the timing belt.

The 1HD-T engine has OHV design with two valves per cylinder. Intake valves are 42.5 mm (1.6732 in) in diameter, and the exhaust valves are 36.0 mm (1.4173 in). Exhaust and intake valves are equipped with irregular pitch springs which are capable of following the valves even at high engine speeds. The 1HD-T engine has a dual-type exhaust manifold.

Adjustment of the valve clearance is done by means of an outer shim type system, in which valve adjusting shims are located above the valve lifters.

Cylinder head
Cylinder head alloyCast iron
Valve Arrangement:SOHV
Valves:12 (2 valves per cylinder)
Intake valves diameter:42.5 mm (1.6732 in)
Exhaust valves diameter:36.0 mm (1.4173 in)
Intake valves length:103.29-103.69 mm (4.0665-4.0822 in)
Exhaust valves length:103.14-103.54 (4.0606-4.00764 in)
Intake valve stem diameter:7.975-7.990 mm (0.3140-0.3145 in)
Exhaust valves stem diameter:7.960-7.975 mm (0.3133-0.3140 in.l
Camshaft journal diameter: 1st: 34.969-34.985 mm (1.3767-1.3774 in)
Others: 27.986-27.998 mm (1.1018-1.1023 in)
Camshaft lobe height (intake):54.440-54.460 mm (2.1433-2.1441 in)
Camshaft lobe height (exhaust):55.940-55.960 mm (2.2024-2.2031 in)

Head tightening procedure and torque specs:

  • Step 1: 69 Nm; 7.0 kg·m; 51 ft·lb
  • Step 2: Turn all bolts 90°
  • Step 3: Turn all bolts 90°

Camshaft bearing cap

  • 25 Nm; 2.5 kg·m; 18 ft·lb

Maintenance data

Valve clearance (Cold)
Intake valve0.15-0.25 mm (0.006-0.0098 in)
Exhaust valve0.35-0.45 mm (0.0137-0.0177 in)
Compression pressure
Standard35.0 kg/m2 (3,432 kPa, 498 psi) / 250 rpm
Minimun25.0 kg/m2 (2,452 kPa, 358 psi) / 250 rpm
Compression differential limit between cylinders5.0 kg/m2 (490 kPa, 71 psi) / 250 rpm
Oil system
Recommended engine oil10W-30 or 10W-40 (“CD” or higher: “CH”, “CI”)
Engine oil capacity Dry fill: 9.6 L (10.6 US qt, 8.8 Imp. qt)
With oil filter change: 9.7 L (10.3 US qt, 8.5 Imp. qt)
Without oil filter change: 8.4 L (8.9 US qt, 7.4 Imp. qt)
Fuel system
Plunger stroke:1.29-1.35 mm (0.0507-0.0531 in.)
Idling M/T: 700 ± 50 rpm
A/T: 800 ± 50 rpm

Vehicle applications

ModelYears Produced
Toyota Land Cruiser (HDJ80)1989-1995
Toyota Coaster (HDB20)1990-1993
Toyota Coaster (HDB30)1990-1993
Toyota Coaster (HDB50)1993-1995
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