The Vauxhall 28 S is a 2,784 cc, inline‑six naturally aspirated petrol engine produced between 1978 and 1986. It features an overhead valve (OHV) layout with a single downdraft carburettor and cast‑iron block construction. In standard tune it delivered 115 bhp (86 kW) at 4,400 rpm and 160 lb·ft (217 Nm) of torque at 2,200 rpm, providing smooth, relaxed performance ideal for executive sedans and estates.
Fitted to models such as the Carlton Mk1, Viceroy, and Senator A, the 28 S was engineered for refined, torque‑oriented motoring with mechanical simplicity and ease of service. Emissions control remained minimal, with most units complying only with pre‑Euro or Euro 0 norms, as formal EU emissions legislation had not yet been enacted during its production run.
One documented concern is head gasket failure under sustained high load or overheating, highlighted in Vauxhall Engineering Bulletin EB‑81‑12. This stems from the original composite head gasket design and thermal stress at the cast‑iron block/aluminium head interface, leading to coolant contamination and loss of compression. From 1983, revised multi‑layer steel (MLS) gaskets were introduced.
Production years 1978–1982 meet pre‑Euro emissions norms; 1983–1986 models may include minor durability updates but remain Euro 0 compliant (VCA UK Type Approval #VCA/EMS/6521).
The Vauxhall 28 S is a 2,784 cc inline‑six OHV petrol engine engineered for executive sedans and estates (1978–1986). It combines a single carburettor with robust cast‑iron construction to deliver smooth power delivery and strong low‑rpm torque. Designed before formal EU emissions standards, it prioritizes drivability and serviceability over emissions control.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,784 cc | |
| Fuel type | Petrol (unleaded post‑1979 with hardened valve seats) | |
| Configuration | Inline‑6, OHV, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 95.2 mm × 98.0 mm | |
| Power output | 115 bhp (86 kW) @ 4,400 rpm | |
| Torque | 160 lb·ft (217 Nm) @ 2,200 rpm | |
| Fuel system | Single downdraft carburettor (Zenith/Stromberg) | |
| Emissions standard | Pre‑Euro / Euro 0 (no formal standard) | |
| Compression ratio | 8.0:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain‑driven camshaft (front mounted) | |
| Oil type | SAE 20W‑50 mineral oil (API SC/CC) | |
| Dry weight | 172 kg |
The inline‑six OHV layout provides exceptional smoothness and strong low‑rpm torque but lacks high‑rpm efficiency. All 28 S engines were built post‑1979 and include hardened valve seats, making them compatible with modern unleaded fuel. Regular valve clearance checks (every 6,000 miles) are essential. The cast‑iron block with aluminium head creates thermal stress risks; maintaining cooling system integrity is critical to prevent head gasket failure. Carburettor tuning should follow OEM jetting specifications, and ethanol‑resistant rebuild kits are recommended for long‑term reliability with modern fuels.
Oil Specs: Requires SAE 20W-50 mineral oil meeting API SC/CC (Vauxhall Owner’s Handbook Senator A 1980). Modern classic‑car oils with ZDDP are suitable.
Emissions: No formal EU emissions standard applied during production (VCA Type Approval #VCA/EMS/6521). Lead‑free compatibility standard from 1979.
Power Ratings: Measured under BS AU 141a (British Standard). Output consistent across Carlton/Viceroy/Senator applications (Vauxhall PT‑1979).
Vauxhall Technical Information System (TIS): Workshop Manuals Carlton/Senator
Vauxhall Engineering Bulletins: EB‑81‑12, EB‑79‑08
VCA Type Approval Database (VCA/EMS/6521)
British Standards Institution: BS AU 141a
The Vauxhall 28 S was used across Vauxhall's executive and large family car platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations—reinforced mounts in the Senator and revised cooling ducts in the Viceroy—and from 1983 the introduction of multi‑layer steel head gaskets, creating service part compatibility limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the left-hand side of the block near the distributor mount (Vauxhall TIS CA‑125). The code '28S' is cast into the block and appears on the compliance plate under the bonnet. All units feature hardened valve seats. Differentiate from the 25S (2,490 cc) by displacement badge and larger bore—28S uses Zenith 38IV or Stromberg 150CD carburettors. Engine numbers beginning with '28S' confirm identity; cross‑reference with VIN chassis plate for model year verification.
The 28 S's primary reliability risk is head gasket failure in pre‑1983 units, with elevated incidence in high‑load or overheating conditions. Vauxhall service data from 1982 noted increased warranty claims for coolant contamination and compression loss, while UK DVLA workshop records show frequent timing chain and carburettor faults in preserved examples. Infrequent oil changes and cooling system neglect accelerate wear, making adherence to service intervals critical.
Analysis derived from Vauxhall technical bulletins (1978–1986) and UK DVSA failure statistics (1985–1995). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VAUXHALL 28-S.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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