BMW 320 320/6 323i E21 M20 Engine Workshop Manual Section 11

Description

Complete Service & Overhaul Guide for the BMW E21 M20 6-Cylinder Powerplant

The BMW 320 320/6 323i E21 M20 Engine Workshop Manual Section 11 is the definitive technical workshop publication dedicated specifically to the mechanical diagnosis, dismantling, inspection, reconditioning, and assembly of the classic inline 6-cylinder engine powering BMW E21 chassis models. Covering both the carbureted 2.0-liter BMW 320/6 and the Bosch K-Jetronic fuel-injected 2.3-liter BMW 323i, this manual provides workshop-level procedures developed directly by BMW service engineering. Whether undertaking a complete bottom-end rebuild, cylinder head remachining, timing belt replacement, or running complete oscillograph diagnostics on the ignition and charging systems, this document delivers original factory specifications, exact tolerances, and dedicated special service tool instructions.

File Details

• Manual Type: Factory Engine Workshop Manual (Section 11 Engine)
• Brand: BMW
• Models Covered: BMW 320/6, BMW 320/6 Automatic, BMW 323i, BMW 323i Automatic (including Swedish and Austrian market variants)
• Engine Types: BMW M20 (small inline 6-cylinder SOHC, 1990 cm³ and 2316 cm³)
• Language: English
• Page Count: 121 pages
• Document Date / Edition: 2.78 (February 1978 Edition)
• File Format: High-resolution digital PDF

Chapters Covered

• 11 Engine Specifications: General engine data, compression ratios, power/weight metrics, engine block reboring dimensions, cylinder head dimensions, valve guide and seat shrink fits, crankshaft journals and bearing shells, flywheel machining limits, connecting rod tolerances, piston barrel and ring groove measurements, camshaft bearing bores, valve timing and spring tensions, intermediate shaft dimensions, oil pump clearances, and comprehensive tightening torques
• 11 00 005 Diagnosis with BMW Program Tester / Digital Tester: Battery testing, terminal 15 voltage drop, contact breaker inspection, capacitor series resistance, alternator diode oscillograph patterns (positive, negative, and exciter diode failure wave forms), dwell angle adjustment, distributor cam displacement, centrifugal and vacuum ignition advance/retard curves, cylinder comparative balance testing, exhaust emission CO analysis, and fuel pump delivery pressure testing
• 11 00 039 Checking Compression of All Cylinders: Step-by-step test procedure, fuel pump and diode relay isolation on fuel injection engines to prevent flooding, test parameters, and gauge readings
• 11 00 050 Engine Removing and Installing: Full disconnection sequences, engine compartment preparations, engine lifting beam 11 0 020 attachment, electrical harness routing, carburetor vs. fuel injection line disconnections, and engine mount realignment
• 11 11 160 Distributor Shaft Bearings: Removal, bearing renewal, and installation on the engine block
• 11 12 000 Cylinder Head Cover & 11 12 100 Cylinder Head: Removal, cleaning, stripping, and installation procedures
• 11 12 101 Renewing Cylinder Head Gasket: Two-stage crosswise tightening sequence, torque specifications, and cold engine temperature conditions
• 11 12 240 Timing Case Cover Radial Seal: Front sealing ring replacement and gasket alignment
• 11 12 561 Renewing One Valve Guide: Driving out worn guides with special tool 11 1 330, cylinder head heating instructions, driving in oversize guides with tool 11 1 320 to strict 14.5 mm installed projection depth, and 7H7 reaming
• 11 12 607 Machining Valve Seats and Valves: Seat recutting, minimum valve head edge thicknesses, seat widths, and lapping with grinding paste
• 11 12 719 Grinding Cylinder Head Mating Surface: Permissible machining limits (max 0.3 mm removal) from original head height of 125.1 mm, and thicker head gasket requirements
• 11 12 729 Cylinder Head Water Leak Test: Pressure sealing with special test rails 11 1 021 and sealing plates 11 1 023, 11 1 024, and 11 1 025
• 11 13 000 Removing and Installing Oil Sump: Sump removal, sealing with joint compound, and torque tightening
• 11 14 175 Front End Cover & Radial Seals: Front cover removal, replacement of radial oil seals using driving sleeve 11 1 260 and guide sleeve 11 2 213, and joint sealing with Atmosit / Curil K2
• 11 14 611 Radial Seal in End Cover (Clutch End): Rear main oil seal replacement and carrier sealing
• 11 21 000 Crankshaft Removing and Installing: Crankcase mounting to assembly stand 00 1500, crankshaft endplay check, Tenifer surface treatment guidelines, main bearing shell color code matching (red/blue), and Plastigage PG 1 clearance measurement
• 11 21 571 Needle Roller Race in Crankshaft: Extraction using puller 11 2 010, arbor installation to exact 5.0 mm depth, and packing with multipurpose grease
• 11 22 000 Flywheel & Starter Gear Ring: Flywheel removal, runout inspection, ring gear renewal, and drive plate service for automatic transmissions
• 11 24 521 Renewing All Connecting Rods: Weight matching within 4g tolerance, checking deviation from parallel and twist limits, and small end bushing inspection
• 11 25 000 All Pistons Removing and Installing: Piston removal, ring stagger at 120°, piston crown arrow orientation towards toothed belt, gudgeon pin fit, and angle-of-rotation rod bolt torquing using tool 11 2 110
• 11 25 651 Piston Rings Renewal: End gap and vertical groove clearance measurements, ring orientation (TOP mark towards piston crown), and oil scraper ring spring fitting
• 11 31 000 Camshaft & 11 31 100/110 Toothed Belt Service: Toothed belt tensioning, belt replacement, sprocket alignment, and camshaft withdrawal through the cylinder head
• 11 33 020 Rocker Arm Shafts & Rocker Arms: Shaft extraction, rocker arm inspection, and clamping bolt reinstallation
• 11 34 004 Valve Clearance Adjustment: Cold clearance adjustment (0.25 mm) via eccentric adjusters, leak testing, and valve replacement
• 11 35 020 Intermediate Distributor Shaft: Removal, bushing inspection, and gear drive reinstallation
• 11 41 000 Oil Pump & Pressure Relief Valve: Pump removal, gear backlash and endplay checking, pressure relief spring length checks, and drive gear engagement
• 11 51 000 Water Pump & 11 53 000 Thermostat: Water pump overhaul, impeller clearance checks, thermostat start-of-opening testing (80°C), and thermo valve testing
• 11 61 000 Intake System & 11 74 051 Thermo Valve: Manifold removal, carburetor sealing, intake air collector servicing, and emission control thermo valve temperature testing

Together, these technical sections provide technicians with an exhaustive, step-by-step master guide for reconditioning every moving component of the M20 6-cylinder engine. From early diagnostic triage with workshop oscilloscopes down to the final torque angle on the connecting rod caps, every operation is presented with factory precision.

Comprehensive Engine Specifications & Factory Torques

Working on the classic BMW small six requires strict adherence to factory-specified tightening torques and machining limits. The BMW 320 320/6 323i E21 M20 Engine Workshop Manual Section 11 provides exhaustive data tables covering:

• Cylinder Head Fasteners: Two-stage torque specification (Stage 1: 30 to 35 Nm / 22 to 26 lb.ft; Stage 2: 60 to 65 Nm / 44 to 48 lb.ft) carried out in a strict center-outward crosswise pattern on a cold engine.
• Connecting Rod Big-End Bolts: Tightened initially to 20 Nm (14.7 lb.ft), followed by a mandatory 70-degree angle of rotation using BMW angle torque tool 11 2 110 (always replacing bolts when rebuilding).
• Main Bearing Caps: Torqued to 58.9 to 65.7 Nm (43.4 to 48.4 lb.ft) with bearing clearances checked individually using Plastigage PG 1.
• Crankshaft Vibration Damper Central Hub: Heavy-duty M18 x 1.5 hex bolt torqued to 392.3 to 432.1 Nm (298 to 319 lb.ft).
• Flywheel to Crankshaft: Torqued to 98.1 to 112.8 Nm (72 to 83 lb.ft) secured with Loctite No. 270 compound.
• Toothed Belt Sprockets: Camshaft M10 bolt torqued to 54.9 to 64.7 Nm (40.5 to 47.7 lb.ft); intermediate shaft M10 bolt torqued to 39.3 to 43.2 Nm (29 to 32 lb.ft).
• Precision Clearances: Piston installed clearance of 0.035 ± 0.010 mm; valve operating clearance of 0.25 mm cold; crankshaft axial endplay limits (0.080 to 0.163 mm); and connecting rod permissible twist of 0° 30′.

IMAGES PREVIEW

Electrical & Oscilloscope Diagnostic Systems

A notable feature of this manual is its extensive coverage of factory diagnostic procedures using the BMW program tester and digital tester. It details troubleshooting protocols for both contact-breaker and contactless transistorized coil ignition systems. Step-by-step oscillograph analysis instructions guide the technician through identifying defective alternator diodes (open or short-circuited positive, negative, or exciter diodes), measuring capacitor series resistance, setting dwell angles (35° to 41° on mechanical points or checking the fixed electronic dwell curve of 42° ± 10° at 1500 rpm), testing cam lobe displacement, and calibrating both centrifugal and vacuum advance/retard curves. These procedures allow vintage BMW enthusiasts and specialist mechanics to tune the ignition curve and cylinder balance to exact factory parameters.

Professional Capability, Delivery & Workshop Value

Whether you are performing routine maintenance like setting valve clearances and replacing the rubber toothed timing belt, or executing a bare-block engine blueprinting job, having the exact technical manual ensures the longevity and performance of your BMW E21. Guesswork risks costly damage to Tenifer-treated crankshafts, aluminum cylinder head castings, and delicate valve trains. This digital PDF manual is available for immediate download right after payment—giving you instant access on your workshop computer, tablet, or smartphone without waiting for shipping. Every diagram, clearance table, and repair sequence is cleanly readable and printable, allowing you to print out specific pages to carry directly over to the workbench.