How-To & Repairs
Task-focused, plain-English guides written for AC Aceca owners. Every guide is original; precise torque and clearance figures defer to the workshop manual; safety-critical or specialist work should always be entrusted to a specialist.
- CoolingDIY2–3 hours plus draining time
Flush and refill the cooling system
A biennial cooling-system flush is the single most valuable maintenance job on an Aceca. It removes scale and old inhibitor that quietly line the radiator core and cylinder-head passages, letting the system shed heat properly and preserving the radiator.
Open the guide - FuelDIY / Specialist1–2 hours with the engine warm
Balance and mixture-set triple carburettors
The three carburettors on any Aceca must draw equal airflow at idle before mixture can be sensibly set. This is done with a balance meter, each carburettor's throttle stop adjusted independently, then mixture walked in per carburettor until idle is smooth.
Open the guide - IgnitionDIY1 hour
Set points, dwell and ignition timing
Setting points gap, dwell and ignition timing on the Lucas distributor is straightforward when done in the right order. Static-time to get the engine running cleanly, then strobe-time warm with a timing light for the definitive setting. All figures come from the workshop manual for the specific engine.
Open the guide - BodyDIY / SpecialistHalf a day plus paint drying
Arrest early aluminium-body corrosion
Blistering or white powder on an Aceca panel is usually galvanic corrosion where the aluminium skin meets the steel body frame; separately, the ash timber in the frame can rot where damp is trapped. Both are arrestable if caught early and ruinous if ignored. This guide covers cosmetic touch-in only — structural frame repair is a coachbuilder's job.
Open the guide - BrakesDIY1 hour with two people
Change brake fluid and bleed the system
Brake fluid absorbs water from the atmosphere and should be renewed every two years or so. Old fluid drops the boiling point of the system, causing a spongy pedal or fade under repeated braking. The job is straightforward with two people and takes an hour.
Open the guide - ElectricalDIY / Specialist2–3 hours
Diagnose the Lucas dynamo and control box charging system
The Aceca charges through a Lucas dynamo and a separate control box, not an alternator. Most charging complaints are a slipping belt, poor earths, a dirty or mis-set control box, or worn dynamo brushes — rarely the dynamo failing outright. Confirm the car's earth polarity before connecting anything, as reversed polarity destroys components.
Open the guide - TransmissionDIY / Specialist1–3 hours to diagnose
Maintain the gearbox, clutch and overdrive
The Aceca has a four-speed manual gearbox — a Moss box on AC-engined cars, Bristol's own on the Aceca-Bristol, an AC alloy-cased box on the 2.6 — often with a Laycock de Normanville overdrive on the upper gears. Most 'gearbox' faults are really clutch, linkage or overdrive-electrics problems, so diagnose before dismantling.
Open the guide - EngineDIY1 hour to investigate
Read and protect the engine's oil pressure
Oil pressure is the clearest indicator of health on the Aceca's six-cylinder engines. Learn your engine's normal hot and cold readings from the manual, watch for a low hot-idle figure, and act on any downward trend early — most bottom-end damage follows months of quietly falling pressure that was there to be seen.
Open the guide - EngineDIY / Specialist2–3 hours, unhurried
Check and set the valve clearances (Bristol engine)
The Bristol six sets its valve clearances through an unusual cross-pushrod head: one camshaft in the block works the inlet valves directly and the exhaust valves through transverse pushrods that cross the top of the head. There is more linkage to understand and to wear than on a normal engine, so work methodically to the manual's figures — and if in any doubt, use a Bristol specialist.
Open the guide - CoolingDIY / SpecialistAn afternoon, worked through methodically
Diagnose an overheating Aceca
An Aceca that runs hot almost always has a findable cause: a furred or blocked radiator core, a weak water pump, a stuck thermostat, retarded ignition or a weak mixture, a slipping fan belt, or simply air in the system after coolant work. Work through them in order — cheapest and most likely first — before assuming the worst.
Open the guide