Buying & Restoring
Restoration Guide
The 504 is mechanically robust but susceptible to corrosion in predictable locations. Know what to look for before you buy.
Buying & Restoring
The 504 is mechanically robust but susceptible to corrosion in predictable locations. Know what to look for before you buy.
Prioritise structural rust over mechanical issues. Engines and running gear are durable and well-supported by parts — serious bodywork rot can make a car unrestorable or extremely expensive to fix.
Bodywork
Inspect these areas first and most carefully on any prospective purchase:
Severity: High · Structural. Costly to repair properly. Open the bonnet and push down on each front corner — any give indicates a problem. Critical for MOT and safety.
Severity: High · Structural. Often hidden by cladding or body filler. Get underneath with a torch. Poke with a blunt instrument to test for rust bubbling or collapse.
Severity: High · Structural. Check from underneath — particularly under the front and rear seats. A rotten floor pan is expensive to repair correctly.
Severity: High · Safety-critical. Directly affects handling and safety. Inspect the inner wheel arch and the trailing arm mounting points.
Severity: Medium-High. Check behind rubber trim where water collects. Look for blistering paint on the outside arch lip.
Severity: Medium. Common and often visible. Check all four doors in the bottom 5cm — the fold traps moisture.
Severity: Medium. Cosmetic but often advanced. Can indicate that the floor has been wet as well.
Italian-built Coupés and Cabriolets are especially susceptible to rot due to the Turin production environment. Inspect these more carefully than sedans. The Cabriolet's sills and floor are particularly at risk. Allow significantly more budget for bodywork restoration on a two-door.
Older cars will need these replaced — check for excessive bounce and handling vagueness. Renewal transforms the driving feel.
Age-related electrical fragility. Check all lighting and instrument functions. Dry, brittle insulation is a fire risk.
Original manifolds crack with age. Budget for replacement — cracks cause noise and affect engine performance.
Hoses, master cylinder, and calipers all age. Budget for a full overhaul: fresh fluid, new hoses, rebuilt calipers.
Renewal is straightforward and transforms the driving feel. Alignment should be checked after any suspension work.
| Engine | Main Concerns |
|---|---|
| XD88 / XD90 Diesel | Extraordinarily durable if maintained. Check injector condition and injection timing. Look for weeping around injectors. |
| XN 2.0L Petrol | Reliable. Check for oil leaks at rocker cover and sump. Watch for head gasket condition on high-mileage examples. |
| PRV V6 | Requires more careful maintenance. Check K-Jetronic injection condition on late cars. Timing chain and tensioner wear. ZF automatic can be expensive to rebuild. |
Sourcing
Parts availability is reasonable for a car of its age, with specialist suppliers in France and Germany covering most mechanical and body needs. Two-door trim is the hardest category.
· The XD diesel family was used in agricultural, industrial, and marine applications — parts are findable from non-automotive sources.
· The PRV V6 is shared with Renault 25/30 and Volvo 264/265 — check Volvo and Renault specialists when Peugeot sources run dry.
· Argentine parts for Argentine-spec cars need Argentine sources — Sevel's supply chain was separate.