Turbo Diesel
1.9L TDI ALH Engine
Complete technical specifications from official VW repair manuals. The legendary ALH TDI - famous for 500,000+ mile reliability, 40+ MPG economy, and strong tunability.
1896cc
Displacement
66 kW
90 hp @ 3,750 RPM
210 Nm
@ 1,900 RPM
79.5 × 95.5
Bore × Stroke (mm)
19.5:1
Compression
GT1749V
Turbocharger
ALH Engine Design
1.9 TDIEngine Configuration
- TypeInline 4-cylinder
- Block MaterialCast iron
- Head MaterialAluminum alloy
- ValvetrainSOHC 8-valve
- Fuel SystemBosch VP37 rotary pump
- Injection TypeIndirect (swirl chamber)
Turbocharger System
- Turbo ModelGarrett GT1749V (VNT15)
- WastegateVariable geometry (VNT)
- Boost Pressure (max)0.95 bar
- Actuator TypeVacuum controlled
- IntercoolerSide-mount air-to-air
Legendary Reliability
The ALH is renowned for exceptional longevity. Multiple documented examples have exceeded 500,000 miles on original internals. The cast iron block, simple 8-valve head, and robust injection pump contribute to its durability. Proper maintenance (especially fuel filter and timing belt) is critical.
Crankshaft Specifications
Rep. Gr. 13Crankshaft Dimensions
- TypeForged steel
- Main Bearings5
- Main Journal Diameter54.0 mm
- Rod Journal Diameter47.8 mm
- Axial Play (New)0.07-0.17 mm
- Axial Play (Limit)0.25 mm
- Radial Clearance (New)0.03-0.08 mm
Oil Pump
- TypeGerotor
- DriveDirect from crank
- Relief Pressure4.5-5.0 bar
- Idle Pressure (warm)≥ 0.8 bar
- @ 2000 RPM2.0-3.5 bar
Fuel Injection System
VP37Injection Pump (VP37)
- TypeBosch VP37 rotary
- DriveTiming belt
- Injection Pressure~190 bar
- Timing AdjustmentElectronic (solenoid)
- Quantity ControlECU via solenoid
Injector Specifications
- Type2-hole pintle
- Opening Pressure190 ± 8 bar
- Spray PatternInto prechamber
- Glow Plug TypePencil type (M10)
- Glow Time (cold)~10 seconds
Injection Pump Timing Critical
The VP37 injection pump timing is set via timing belt. Incorrect timing causes hard starting, smoke, poor economy, and potential engine damage. Always verify pump timing when replacing timing belt. Use VW special tool 3359 for accurate static timing.
Torque Specifications
Official VW SpecsCylinder Head & Valvetrain
Cylinder head bolts (Stage 1)40 NmAll bolts
Cylinder head bolts (Stage 2)60 NmAll bolts
Cylinder head bolts (Stage 3)+ 90°Replace bolts
Cylinder head bolts (Stage 4)+ 90°Final pass
Camshaft bearing caps20 NmSequence critical
Camshaft sprocket bolt45 NmUse counterhold
Rocker arm shaft bolts20 Nm
Crankshaft & Block
Main bearing cap bolts65 Nm + 90°Replace bolts
Connecting rod bolts30 Nm + 90°Replace bolts
Crankshaft pulley bolt90 Nm + 90°Replace bolt
Flywheel bolts60 Nm + 90°Replace bolts
Oil pan bolts15 Nm
Oil drain plug30 NmNew washer
Fuel System & Turbo
Injection pump sprocket25 Nm
Injector hold-down20 Nm
Glow plugs15 NmAnti-seize
Turbo to manifold nuts25 NmNew gasket
Exhaust manifold nuts25 NmNew gasket
Timing Belt System
Timing belt tensioner20 NmAfter tensioning
Timing belt idler25 Nm
Water pump bolts15 Nm
Cooling & Lubrication
SpecificationsCoolant Specifications
- TypeG12 Pink
- Capacity6.5L (6.9 qt)
- Thermostat Opens87°C (189°F)
- Operating Temp85-105°C
Oil Specifications
- VW SpecificationVW 505.00
- Recommended5W-40 Diesel Synthetic
- Capacity with Filter4.5L (4.8 qt)
- Change Interval10,000 mi max
Tuning Potential
PerformanceChip Tune
110-130 hp
Modifications
- ECU reflash / chip tune
- Increased fueling
- Adjusted boost limits
Notes
- Stock turbo still efficient
- Significant torque increase
- Maintains reliability
- 50+ MPG still achievable
Hardware Mods
130-160 hp
Modifications
- Larger injector nozzles
- Boost controller
- EGR delete
- 3" exhaust
Notes
- VNT turbo near limit
- Stock transmission handles it
- EGT gauge recommended
Big Turbo
180-250+ hp
Modifications
- Larger turbo (GT17/GT20)
- Bigger injectors
- Standalone boost control
- Built transmission
Notes
- VP37 pump limit ~240 hp
- Head studs recommended
- Intercooler upgrade
Common Issues & Maintenance
TroubleshootingKnown Problem Areas
- Timing BeltReplace every 100k mi
- VNT ActuatorSticking/seized vanes
- Glow PlugsFailure in cold climates
- MAF SensorContamination
- EGR ValveCarbon buildup
- Injection PumpSeal leaks at high miles
Maintenance Intervals
- Oil Change5,000-10,000 mi
- Timing Belt100,000 mi (CRITICAL)
- Fuel Filter20,000 mi
- Air Filter30,000 mi
- CoolantEvery 5 years
- Trans Fluid (manual)60,000 mi
Timing Belt is Critical
The ALH is an interference engine. Timing belt failure will cause catastrophic valve-to-piston contact. Replace belt, tensioner, and water pump together every 100,000 miles or 10 years, whichever comes first. Do not exceed this interval.
Vehicle Applications
1.9 TDI ALH| Vehicle | Years | Notes |
|---|---|---|
| VW Golf TDI Mk4 | 1999-2003 | USA market, 5-speed manual |
| VW Jetta TDI Mk4 | 1999-2003 | USA market, 5-speed manual |
| VW New Beetle TDI | 1999-2003 | USA market |
| VW Golf TDI Mk3 | 1996-1999 | Final Mk3 TDI years |
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Timing Belt Kit TDI ALH
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Glow Plug Set TDI
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Fuel Filter TDI
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EGR Delete Kit TDI
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Injector Nozzle Set TDI
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Turbo Upgrade TDI ALH
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