Description

Alfa Romeo 155, 155 Q4 1991 Repair Manual

You’re staring at a 155 Q4 that’s overheating, the transfer case is whining, and the last guy used a generic torque chart from a forum. I’ve pulled engines out of these cars after someone guessed on the head bolt sequence. This Alfa Romeo 155, 155 Q4 1991 Repair Manual is the OEM supplement – 985 pages printed by Alfa Romeo in December 1991. It covers the 155 and the 155 Q4 with the integrated four-wheel-drive system. If you’re working on one of these, you need the factory tolerance for the rear differential preload, not some aftermarket reprint that says “tighten until snug.”

What This Factory Manual Actually Covers

This supplement is laid out in four main sections: Moteur, Groupes Mecaniques, Chassis, and Diagnostic Electrique-Electronique. Inside Moteur you get the full breakdown of the engine group – alimentation, allumage, démarrage, recharge, refroidissement. Page 1 of the manual calls it out clearly: it’s a supplement for the 155 Q4, meaning it adds the Q4-specific procedures to the base 155 manual. The Groupes Mecaniques section includes the clutch (Embrayage), the gearbox, torque splitter, differential and transfer case (BV, Répartiteur couple, Diff et Renvoi), and the transmission itself. That’s where you’ll find the shim specs for the rear axle.

Does This Manual Cover the 155 Q4 Transfer Case?

Yes, and it’s the only source I trust for the integrated rear drive unit. The chapter “Pont Arriere transmission intégrale” gives you the assembly clearances and seal installation depths. I’ve seen aftermarket manuals skip the step that shows the preload sequence for the tapered roller bearings on the rear axle. This manual includes it. Also covered: the half shafts (Demi-Arbres Transmission) and the front and rear brakes. If you’re replacing a driveshaft on a Q4, you want the factory step for pulling the stub shaft without damaging the viscous coupling.

985 Pages of OEM Specs

Every torque value, every fluid capacity, every electrical pinout came out of the Alfa Romeo engineering office. The Diagnostic Electrique-Electronique section (about 200 pages of schematics and test procedures) is a goldmine for tracking down intermittent EFI faults on the 155 Q4. The manual includes the update sheets dated 12/1994 – so it covers revisions to the chassis and electrical sections. You aren’t working from a third-party scan; this is the actual factory binder material.

Get the Right Torque Data for the Suspension

The suspension chapters – front and rear – list the factory torque for every bolt: lower control arm pivot, strut top nut, rear trailing arm. The 155 Q4 uses different rear suspension components than the base 155. If you reuse the old bolts without the specified thread-locker and torque, the car will handle like a grocery cart. I keep this manual within arm’s reach of the lift when I’m doing a suspension R&R on these Alfas. It also covers steering (Direction), wheels and tires (Roues et pneumatiques), and the air conditioning system (Climatisation).

Source Authenticity: Why Aftermarket Manuals Fail

Aftermarket manuals like Chilton or Haynes have their place, but for an Alfa 155 Q4 they skip the fine details – especially the electrical diagnostics for the Bosch Motronic system and the ABS wiring. This is the factory supplement, printed by Alfa Romeo, with the part number PA4735004x4000. The update records show 18 sections were revised in 1994. You won’t get that level of detail from any generic manual. I’ve compared the wiring diagrams in this manual to the actual harness on a 1993 155 Q4 – they match connector pin colors, something no aftermarket book gets right.

Need related manuals for other Alfa projects? Check the Alfa Romeo 33, 155, 166, 145, 145 1.6 Technical Manual – Speed Signal Pickup for picking up speed signals, or the Alfa Romeo 156 (1997-2003) Repair & Operation Manual if you’re working on a later model. For an older car, the Alfa Romeo 33 Air Conditioning Installation Manual covers the A/C retrofit on the 33 series.

For broader context on how OEM documentation improves repair outcomes, read the Automotive Industry Overview and Automotive Industry Overview.

Is this manual in French or English?

It’s entirely in French – the original factory supplement for European markets. If you can read French or use a translator, the schematics and torque tables are universal. The wiring diagrams use international symbols.

Does it cover the base 155 non-Q4?

This supplement is titled “SUPPLEMENT POUR 155 Q4” and assumes you already own the base 155 manual. It adds the Q4-specific sections: rear axle, transfer case, and related diagnostics.

What torque specs are included?

All of them. Every fastener listed in the Groupe Moteur, Transmission, Suspension, and Freins chapters has a specified torque in Nm. The manual also includes tightening sequences for the cylinder head and the differential bearing caps.

Is this a PDF or a printed book?

It’s a digital PDF format of the original factory binder. 985 pages, fully scanned, with the 1994 update sheets. You can print the sections you need or keep it on a tablet in the shop.

Stop guessing on your Alfa 155 or 155 Q4. Get the factory data that every master tech I know uses. Access the Factory Manual today and start with the correct specs for your next repair.