Alfa Romeo1998–2001Technical specifications

166 2.5: Technical specifications

Workshop data for the 2.5-litre petrol (engine code 342.01). Covers engine, fluids, brakes, service, torques and air conditioning: the figures to check before a job or a parts order.

Common faults & fixes

Summary

Match the engine code (342.01) to the vehicle before ordering parts or applying these figures.

Vehicle specifications

Overview

Make
Alfa Romeo
Model
166
Years
1998–2001
Fuel
Petrol
Engine code
342.01

Performance & efficiency

Power
140 kW (190 hp)
Engine size
2,492 cc
Cylinders
6 · DOHC
Fuel system
Bosch

Fluids & capacities

Engine oil (with the filter)
5.9 litres
All 94 specifications below

Engine & identification

Vehicle identification

No. of cylinders Type6/DOHC
Capacity (Fiscal) cc2492
Suitable for unleaded petrolYes
Minimum octane rating RON95
Ignition system MakeBosch
Ignition system TypeMotronic ME2.1
Ignition system DescriptionMap-DI
Trigger locationCam/Crankshaft
Fuel system MakeBosch
Fuel system TypeMotronic ME2.1
Fuel system DescriptionMFI-s
Air metering TypeMass
Combined ignition and fuel ECMYes
Diagnostic socketYes

Ignition system

Ignition coil supply voltage + with ballast V12,0
Primary resistance Ohm0,4

Firing order

The firing order for the Alfa Romeo 166 2.5 (1998–2001) is 1-4-2-5-3-6.

Firing order1-4-2-5-3-6

Valve clearances

Valve clearances on the Alfa Romeo 166 2.5 (1998–2001) are hydraulic — they self-adjust, so no manual clearance figure applies.

Valve clearance - INLET mmHydraulic
Valve clearance - EXHAUST mmHydraulic

Engine oil & fluids

Engine oil

The Alfa Romeo 166 2.5 (1998–2001) takes 5.9 litres of engine oil with the filter. The specified engine oil grade is SAE 10W-40 synthetic for all ambient temperatures, with API/ACEA classification SJ/A3.

Manual gearbox

The manual gearbox has a listed capacity of 1.6 litres. The specified oil is SAE 75W-85 synthetic, with classification GL-4.

Coolant

The listed total cooling-system capacity is 10.3 litres.

Grades, filling conditions and capacities

Lubricants and capacities — complete reference
Engine oil options
Ambient temperature range All temperatures
Engine oil grade SAE 10W-40 Synthetic
Engine oil classification API/ACEA SJ/A3
Engine with filter(s) litres 5.9
Other lubricants and capacities
Manual transmission oil grade SAE 75W-85 Synthetic
Manual transmission oil classification GL-4
Manual transmission litres 1.6
Cooling system - total capacity litres 10.3
Brake fluid Type DOT 4
Power steering fluid Type Dexron II

Brakes & wear limits

Brake disc thickness

Brake discs on the Alfa Romeo 166 2.5 (1998–2001) are replaced at a minimum thickness of 24,2 mm (ventilated) front and 9 mm rear.

Minimum disc thickness for replacement - ventilated Front24,2 mm
Minimum disc thickness for replacement Rear9 mm

Brake disc and drum dimensions

Minimum pad thickness Front1,5 mm
Minimum pad thickness Rear1,5 mm

Service & electrical

Ignition timing

The ignition timing on the Alfa Romeo 166 2.5 (1998–2001) is not adjustable.

Ignition timing - basic BTDC °Engine/rpmNot adjustable

Tuning and emissions

Ignition advance checks °Engine/rpmECM Controlled
Idle speed rpm700±30 Not adjustable
Oil temperature °C80
CO level at idle speed - tailpipe Vol. % CO0,5 Max Not adjustable
HC level at idle speed ppm100
CO2 level at idle speed Vol. % CO214,5-16
O2 level at idle speed Vol. % O20,1-0,5
Increased idle speed for CO test rpm2500-2900
CO content at increased idle speed Vol. %0,3
Lambda at increased idle λ0,97-1,03

Starting and charging

Battery V/RC(Ah)12
Alternator output A/V/rpm120/14/3000

Service checks and adjustments

Oil pressure bar/rpm4,5/4000
Radiator cap bar0,90-1,00
Thermostat opens °C89

Fuel system

System pressure bar2,8-3,2
Regulated pressure with vacuum bar2,3-2,7
Lambda sensor (Oxygen) heater Ohm8,5-9,5

Spark plugs

Spark plugs Original equipmentNGK
Spark plug TypePFR6B
Electrode gap mm0,8-0,9
Spark plugs MakeNGK
Spark plug TypePFR6B
Electrode gap mm0,8-0,9

Tightening torques

Cylinder head bolt torque

The cylinder head bolts on the Alfa Romeo 166 2.5 (1998–2001) are tightened in 2 stages: 25 Nm, then a final 240°.

Cylinder head
Renew boltsNo
Tighten25 Nm
Tighten240°
Cylinder head instructions—
Other engine tightening torques
Main bearings Renew bolts/nutsNo
Main bearings Stage 125 Nm
Main bearings Stage 279°
Big end bearings Renew bolts/nutsNo
Big end bearings Stage 127-30 Nm
Big end bearings Stage 254-60 Nm
Sump drain bolt64-79 Nm
Flywheel/driveplate116-129 Nm
Clutch pressure plate24-29 Nm
Crankshaft pulley/damper centre bolt200-247 Nm
Camshaft sprocket/gear68-84 Nm
Camshaft carrier/cap18-20 Nm
Camshaft/rocker cover10 Nm
Exhaust manifold to cylinder head22-27 Nm
Spark plugs27-34 Nm
Lambda sensor (Oxygen)50-60 Nm
Knock sensor (KS)19-21 Nm
Chassis tightening torques
Front hub—
Front hub
Rear hub304-336 Nm
Steering track rod end43-47 Nm
Brake caliper/carrier to hub Front160 Nm
Brake disc to hub Rear8-13 Nm
Brake caliper/carrier to hub Rear57 Nm
Road wheels86±8 Nm

Air conditioning

No. of AC service connectors2
Air conditioning restrictor typeExpansion valve
Compressor clutch/magnetic couplingYes
Compressor variable displacement solenoidNo
Air conditioning refrigerant TypeR134a
Air conditioning refrigerant quantity grams700
Air conditioning oil groupPAG
Air conditioning oil TypeSP10
Air conditioning oil quantity cm³135
Air conditioning oil viscosity ISO46

Frequently asked questions

What is the firing order of the Alfa Romeo 166 2.5?

The firing order for the Alfa Romeo 166 2.5 (1998–2001) is 1-4-2-5-3-6.

How much oil does the Alfa Romeo 166 2.5 take?

The Alfa Romeo 166 2.5 (1998–2001) takes 5.9 litres of engine oil with the filter. The specified engine oil grade is SAE 10W-40 synthetic for all ambient temperatures, with API/ACEA classification SJ/A3.

What are the valve clearances for the Alfa Romeo 166 2.5?

Valve clearances on the Alfa Romeo 166 2.5 (1998–2001) are hydraulic — they self-adjust, so no manual clearance figure applies.

What is the cylinder head torque for the Alfa Romeo 166 2.5?

The cylinder head bolts on the Alfa Romeo 166 2.5 (1998–2001) are tightened in 2 stages: 25 Nm, then a final 240°.

What is the ignition timing for the Alfa Romeo 166 2.5?

The ignition timing on the Alfa Romeo 166 2.5 (1998–2001) is not adjustable.

What is the minimum brake disc thickness for the Alfa Romeo 166 2.5?

Brake discs on the Alfa Romeo 166 2.5 (1998–2001) are replaced at a minimum thickness of 24,2 mm (ventilated) front and 9 mm rear.

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