Porsche 928, S, S4, GT & GTS 1978–1995 Workshop Manual Set (P/N WKD 481 621)
2,132 Pages • ZIP Download: 9 Printable PDFs • 200.54 MB
Porsche Models Covered & Key Technical Specifications
Models: 928, 928 S, 928 S4, 928 GT, 928 GTS
Sub-models / Variants: GT (engine M 28.47; manual transmission G 28/55), GTS (manual engine M 28.49 and transmission G 28/57; automatic engine M 28.50 and transmission A 28.18), S4 (manual engine M 28.41; automatic engine M 28.42), Club Sport (engine M 28.41 with identification suffix SP; manual transmission G 28/55), 5-speed Manual, Automatic Transmission; 928 S automatic options M 251 (A 28.03, A 28.06, A 28.09) and M 299 (A 28.11)
Model Years: 1978–1995 (1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995)
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Engine: 8-cylinder, 4-stroke V-engine
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Engine Displacement: 4474 cc to 5397 cc depending on model
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Compression Ratio: 8.5:1 to 10.4:1
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Idle Speed: 675 +/- 25 rpm (GTS model)
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Engine Cooling: Closed system; mechanical fan with viscous coupling on earlier versions, electrically controlled twin fans on later versions
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Transmission: Rear-mounted 5-speed manual or hydraulic torque converter automatic
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Battery Voltage: 12 V
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Camshaft Housing Torque: 20 Nm for the M8 housing-to-cylinder-head fasteners
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928 Engine Codes: M 28.01, M 28.02, M 28.03, M 28.04, M 28.09, M 28.10, M 28.13, M 28.14, M 28.15, M 28.16
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928 S Engine Codes: M 28.11, M 28.12, M 28.19, M 28.20, M 28.21, M 28.22, M 28.43, M 28.44, M 28.45, M 28.46
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928 Transmission Types: 5-speed manual G 28.03 and G 28.05; 3-speed automatic A 22.01 and A 22.02
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928 S Transmission Types: 5-speed manual G 28.08, G 28/10 (Europe/rest of world), G 28/11 (USA); 4-speed automatic A 28.01, A 28.02, A 28.03, A 28.04, A 28.05, A 28.06, A 28.07, A 28.08, A 28.09, A 28.11
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S4 Transmission Types: 5-speed manual G 28/12 (Europe/rest of world), G 28/13 (USA/Japan), G 28/55 (worldwide); 4-speed automatic A 28.12 (USA/Japan), A 28.14 (rest of world), A 28.16 (worldwide)
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Cylinder-Head Gasket Serial Breaks: Revised tightening instructions from engine numbers 80 C 0260 (M 28/09), 80 C 5269 (M 28/10), 82 C 0713 (M 28/11), 82 C 5782 (M 28/12), 81 C 1037 (M 28/15), 81 C 6398 (M 28/16), 80 C 8051 (M 28/17), 80 C 9155 (M 28/18)
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928 S Valve-Spring Serial Breaks: Revised valve springs and cylinder heads from engine number 821 0516 (M 28/11) or 821 5503 (M 28/12 automatic)
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32-Valve Piston Installation Changes: M 28.43, as of 81 G 00594 - 00622; M 28.44, as of 81 G 06311 - 06378
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Knock-Sensor Fastener Serial Breaks: Revised original screw specification from engine number 81 M 51771 (M 28.42) and 85 M 01112 (M 28.47)
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Manual Transmission Serial Breaks: G 28.03 distinguishes up to 118 1092 and from 118 1093; G 28.05 specifies from 110 5001. Special bearing-assembly shim calculations apply to G 28.10 from 11 F 00070 to 11 F 00451 and G 28.11 from 11 F 05069 to 11 F 05322
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Automatic Transmission Protection Switch: From transmission number 16 H 00 564 (USA) and 16 H 10 447 (rest of world)
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A 28 Automatic Transmission Component Changes: B3 damping spring from 379 225; primary-pump cover and thrust-washer change from 472 213; B2 chip screen from 729 001; removable B1 brake-band pressure pin from 788 606
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Clutch Ball-Stud Change: Pressed-in ball stud before chassis number 9288200491
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Front Spring Serial Breaks — Boge Dampers: Blue-coded springs up to 92 A0 80 0645 and white-coded springs from 92 A0 80 0646 (928 Europe/rest of world/Japan); up to 92 A0 81 0714 and from 92 A0 81 0715 (928 USA); up to 92 A0 82 0127 and from 92 A0 82 0128 (928 S)
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928 S Rear Spring Changes: Revised spring-strut components from chassis number 92 ES 840 416 (Europe/rest of world), 92 ES 849 568 (Japan), 92 ES 860 562 (USA)
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Front Body Member Changes: Revised threaded inserts from chassis number 928 910 0025 on five cars initially; standard production from 928 910 0703, 928 920 0514 and 928 920 9534
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Central Locking Vacuum Changes: Separate vacuum circuit from chassis numbers 928 810 0554, 928 830 9521 and 928 820 0054
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Door Lock Cylinder Changes: Revised lock cylinders from chassis numbers 928 810 2412, 928 820 0884 and 928 920 9511
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Rotary-Knob Lock Changes: Revised bearing assembly from chassis numbers 928 810 1853, 928 820 0661 and 928 820 9552
Porsche Manual Features & Selected Content Preview
| Publication | Pages |
|---|---|
| Porsche 928 Workshop Manual, Volume I — engine mechanicals and self-diagnosis (P/N WKD 481 621): 1978–1995 928, 928 S, 928 S4, 928 GT, and 928 GTS applications | 314 |
| Volume I-A — fuel supply, injection, exhaust, starter, cruise control, and ignition | 306 |
| Volume II — clutch, manual transmission, early automatic transmission, and final drive | 397 |
| Volume III — automatic transmission, final drive, and PSD diagnosis | 276 |
| Volume IV — chassis, brakes, steering, heating, and air conditioning | 458 |
| Volume V — bodywork, interior equipment, and electrical systems | 322 |
| Volume VI — alarm diagnosis, electrical corrections, and wiring-harness repair | 29 |
| Volume VII — cover and contents pages only | 4 |
| Combined table of contents | 26 |
Engine mechanical work is documented separately from fuel and ignition diagnosis. Model-specific changes across the volumes help you select the applicable components, test data, and assembly instructions before starting a repair.
Wiring and ABS limits: Complete vehicle wiring-diagram sheets are not included. Volume VII contains only front matter, and Volume VI ends with wiring-harness repair. Tester-based ABS troubleshooting requires the separate test plan WKD 493 720, which is not included.
PDF Search, Links, and Included Pages
Text search and navigation: The workshop volumes have OCR text layers, although recognition errors affect some identifiers and Volume V PDF p. 315 has no usable text layer. The combined contents PDF has working section bookmarks. Cross-file links and the volume bookmarks reference filenames absent from the ZIP. Small labels in the sampled connector and connection plans require zooming.
The ZIP download contains nine printable PDFs totaling 2,132 pages, including the 26-page combined contents and four-page Volume VII front matter, which includes one blank page. Covers, introductions, supplement pages, and repeated pages within the volumes are included in that total.
Engine, Drivetrain, and Vehicle-System Repair
These selected content highlights cover the main workshop areas; additional topics include fuel-tank sensor calibration and seat-heating checks.
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Engine repair: Step-by-step engine removal, crankcase assembly, piston inspection, cylinder-head work, camshaft timing, belt replacement, lubrication service, and cooling-system testing.
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Fuel and ignition diagnosis: CIS, AFC/L-Jetronic, LH-Jetronic, and EZK testing, including fuel pressure, injectors, air-flow sensors, idle/CO settings, and fault-memory diagnosis.
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Transmission and final drive: Clutch service, manual and automatic transmission overhaul, torque-converter work, differential adjustment, central-tube inspection, and PSD hydraulic diagnosis.
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Suspension, steering, and brakes: Wheel-bearing and spring-strut repair, alignment, RDK diagnosis, brake-caliper service, hydraulic bleeding, and power-steering pressure tests.
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Heating and air conditioning: Heater and evaporator removal, compressor service, vacuum-control diagnosis, flap adjustment, and R12/R134a pressure-and-temperature references.
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Body and interior: Structural panel replacement, repair dimensions, foam-filled-cavity precautions, bonded-glass installation, sunroof repair, airbags, and power-seat systems.
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Electrical troubleshooting: Alarm-system tests, central-warning diagnosis, instrument service, connector assignments, lighting checks, and wiring-harness repair.
Written for shop foremen and mechanics, this manual assumes workshop measuring equipment and the system-specific tools identified in its repair sections.
Engine Assembly, Timing, and Lubrication
The engine material distinguishes earlier 16-valve construction from later 32-valve designs. Crankshaft-bearing checks, piston tolerance groups, cylinder-bore inspection, and GTS-specific piston data support internal repair decisions.
Cylinder-head sections include valve-guide replacement, valve-seat machining, spring installation-height checks, and camshaft assignments for S4, Club Sport, GT, and GTS engines. Belt-tension checks specify Special Tool 9201. Lubrication coverage also addresses oil-system cleaning after bearing failure, while cooling sections distinguish viscous-fan systems from later fan and cooling-air-flap controls.
Fuel, Ignition, and Electronic Diagnosis
The diagnosis pages distinguish earlier fault-memory access from the 1989-on 19-pin tester connection. They include actuator and input-signal checks, knock detection, LH/EZK fault-code lists, control-unit coding, and K/L diagnostic-line testing with Porsche System Tester 9288.
CIS and AFC hose diagrams, the fuel-tank breather layout, and Tempostat control-unit pin assignments support component identification and fault tracing.
Transmission and Differential Repair Depth
Internal transmission work includes valve-body and clutch-pack service, bearing and shim selection, backlash adjustment, and central-tube checks. Supplements distinguish later drivetrain changes, including the A 28.18 GTS automatic. PSD sections cover locking-torque measurement, hydraulic testing, and bleeding with the specified test equipment.
An incorrectly seated torque converter can destroy its drive dogs and the automatic transmission’s primary pump. The final-drive instructions also warn against an incorrect shim split that binds the matched drive pinion and ring gear.
Chassis, Climate Control, and Body Systems
Chassis variations: The suspension sections distinguish pre-1986 and 1986-on components, adjustable and non-adjustable struts, and different brake-caliper designs. RDK diagnosis includes control-unit connector assignments and sensor checks.
Climate control: Refrigerant-system layouts, the vacuum-system schematic, flap-position programs, and pressure/temperature charts support diagnosis of the automatic air-conditioning system.
Body and electrical detail: Factory repair dimensions accompany structural panel procedures. Bonded-glass service, airbag diagnosis, seat and mirror controls, and central locking are covered separately. Electrical references include the central-warning-unit black- and yellow-plug connection plans and the model 87/88 circuit-diagram correction. Alarm diagnosis specifies Special Tool 9540.
Fuel, PSD hydraulic, brake, refrigerant, airbag, and heavy drivetrain work requires the isolation, pressure-relief, lifting, and protective measures described in the relevant factory sections.
Sample Bearing-Clearance and Oil-Pressure Specifications
The crankshaft-bearing inspection section lists new main-bearing radial clearance at 0.020–0.098 mm, with a 0.16 mm wear limit. It distinguishes these limits from crankshaft end-play measurements.
The documented oil-pressure test specifies more than 5 bar at 4,000 rpm with the engine at operating temperature, approximately 80°C. The section identifies pressure tester VW 1342 and the required adapters.
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