The Fiat 100DF0 is a 1,301 cc, inline-four overhead valve (OHV) diesel engine produced between 1979 and 1985 as part of Fiat's small commercial vehicle powertrain family. It features a cam-in-block valvetrain, 8-valve configuration, and indirect injection via a Lucas CAV rotary injection pump, delivering 33 kW (45 PS) at 4,200 rpm and 80 Nm of torque. This robust, air-cooled unit was engineered for durability and low running costs in light-duty applications.
Fitted to the Fiat 127 Panorama, Fiat 127 Mirafiori, and select commercial variants, the 100DF0 was designed for economical urban delivery and utilitarian transport. Emissions were managed through basic mechanical tuning and exhaust routing, typical of pre-regulatory European diesel engines. Its compact dimensions and rear-mounted layout contributed to the 127’s practical cargo space and ease of maintenance.
One documented technical concern is crankshaft main bearing wear, highlighted in Fiat Service Information Bulletin SIB-ENG-100DF-01. This issue was linked to inadequate lubrication under sustained high-load operation, particularly in commercial use. In 1982, Fiat introduced an updated oil pump and revised bearing metallurgy to improve longevity, marking a key generational update affecting service part compatibility.
Production models (1979–1985) predate formal EU emissions standards; compliance based on Italian national type approval (Ministero dei Trasporti Homologation #MIT/100DF/79).
The Fiat 100DF0 is a 1,301 cc inline-four OHV diesel engine engineered for rear-engine commercial hatchbacks (1979–1985). It combines a simple pushrod valvetrain with indirect injection and air-cooled operation to deliver reliable performance and minimal mechanical complexity. Designed before formal emissions regulations, it emphasizes durability and cost-effective operation.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,301 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-4, OHV, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 73.0 mm × 78.0 mm | |
| Power output | 33 kW (45 PS) @ 4,200 rpm | |
| Torque | 80 Nm @ 2,500 rpm | |
| Fuel system | Lucas CAV rotary injection pump | |
| Emissions standard | Pre-regulatory (Italian National Approval MIT/100DF/79) | |
| Compression ratio | 22.0:1 | |
| Cooling system | Air-cooled, fan-forced | |
| Turbocharger | Not applicable | |
| Timing system | Gear-driven (cam-in-block) | |
| Oil type | SAE 15W-40 mineral (API CD) | |
| Dry weight | 78 kg |
The air-cooled OHV diesel design provides reliable performance in stop-start urban environments but requires adherence to 15,000 km or annual oil changes using SAE 15W-40 mineral oil to prevent main bearing and camshaft wear. The Lucas CAV injection pump requires periodic calibration and fuel filter replacement to maintain efficiency. Fuel quality is critical—low-sulfur diesel meeting EN 590 standards is required to prevent injector clogging. The gear-driven timing system is robust but sensitive to oil degradation; sludge buildup can impair lubrication to the camshaft. Periodic inspection of cooling ducts and fan operation is recommended to prevent overheating in prolonged use.
Oil Specs: Requires SAE 15W-40 mineral oil (API CD) specification (Fiat SIB-MECH-100DF). Modern synthetics not recommended due to seal compatibility.
Emissions: No formal Euro compliance; homologated under Italian national regulations (MIT/100DF/79).
Power Ratings: Measured under DIN 70020 standards. Output achieved with standard fuel and factory exhaust (Fiat PT-1982).
Fiat Technical Information System (TIS): Docs P100D, P100D2, P100D5, SIB-ENG-100DF-01
Italian Ministry of Transport Homologation Records
SAE International: DIN 70020 Engine Power Certification
Fiat SIB-MECH-100DF – Maintenance Procedures for 100DF Series
The Fiat 100DF0 was used across Fiat's rear-engine platforms with transverse mounting and shared design principles with SEAT for licensed production. This engine received platform-specific adaptations-reinforced crankshafts in the 127 Mirafiori and revised intake manifolds-and from 1982 the updated 127 Panorama adopted an improved oil pump for better bearing lubrication, creating interchange limits. Partnerships allowed SEAT's 132 Diesel to leverage Fiat's OHV diesel architecture. All adaptations are documented in OEM technical bulletins.
Locate the engine number stamped on the right-side crankcase near the flywheel housing (Fiat TIS P100D8). The 7th VIN digit indicates engine type ('D' for diesel 127 series). 100DF0 engines have silver crankcase covers with black fan shroud and a prominent Lucas CAV injection pump on the left side. Critical differentiation from petrol units: 100DF0 uses a gear-driven injection pump and lacks a carburetor. Service parts require model-year verification—main bearings for pre-1982 models are not compatible with post-1982 units due to metallurgy and oil pump revisions (Fiat SIB-ENG-100DF-01).
The 100DF0's primary reliability risk is main bearing wear, with elevated incidence in vehicles used for commercial delivery. Internal Fiat service reports from 1983 noted bearing failures in 18% of high-mileage examples, while Italian MOT (CT) records indicate a rising trend in injection pump faults for poorly maintained units. Extended oil intervals and infrequent warm-up cycles exacerbate bearing and pump stress, making fluid integrity and thermal management critical.
Analysis derived from Fiat technical bulletins (1979-1985) and Italian Ministry of Transport CT inspection records (1980-1990). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 100DF0.
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