page_title: Triumph Stag
section_title: Production
hierarchical_section_title: Triumph Stag / Production
caption_attribution_description: 1977 Triumph Stag Mark 2 at Bristol Car Show, The Downs, Bristol, England.
context_page_description: The Triumph Stag is a 2+2 sports tourer sold between 1970 and 1978 by the British Triumph Motor Company, styled by Italian designer Giovanni Michelotti.
context_section_description: The car was launched one year late in 1970, to a warm welcome at the various international auto shows. The Stag rapidly acquired a reputation for mechanical unreliability, usually in the form of overheating. These problems arose from a variety of causes.
  First, the late changes to the engine gave rise to design features that were questionable from an engineering perspective. For example, the water pump was set higher on the engine than is usual. If the engine became hot in traffic, and coolant escaped from the cooling system via the expansion bottle, the reduced volume of fluid left when the engine cooled down again fell below the level of the pump, which would eventually fail as a result. Water pump failures sometimes occurred due to poorly-hardened drive gears, which wore out prematurely and stopped the water pump.
  A second cause of engine trouble was the lack of attention to corrosion inhibitor in the coolant. The block was made from iron and the heads from aluminium, a combination that required the use of corrosion-inhibiting antifreeze all year round. This point was not widely appreciated by owners or by the dealer network supporting them. Consequently, engines were affected by electrolytic corrosion and white alloy oxide sludge collected in radiator cores, reducing radiator efficiency and causing overheating.  The result was head gasket failure due to cylinder head heat distortion, a very expensive repair. Owners would usually get their repaired cars back with the radiator still clogged, leading to repeat failures.
  A third cause of trouble was the engine's use of long, simplex roller link chains, which would first stretch and then often fail inside fewer than 25,000 miles (40,200 km), resulting in expensive damage. Even before failing, a stretched timing chain would skip links and cause valves to lift and fall in the wrong sequence, so that valves hit pistons and damaged both. This fault may have been worsened by poor quality chains.
  Another problem with the cylinder heads was said to be the arrangement of cylinder head fixing studs, half of which were vertical and the other half at an angle. Anecdotally, this arrangement was used to reduce production costs, as the cylinder head mounting studs and bolt were all accessible with the rocker covers fitted. This allowed the factory to assemble the cylinder head completely before fitting to the engine. The same arrangement worked well enough on the 4-cylinder engines, but in the V8 the angled and vertical studs, when heated and cooled, expanded and contracted in different directions sufficiently to give rise to sideways forces that caused warping of the engine block.
  Finally, although pre-production engines cast by an outside foundry performed well, those fitted to production cars were made inhouse by a plant troubled with industrial unrest and inadequate quality control. Engines are still being discovered with casting sand inside, blocking the coolant passages and causing overheating.
  This combination of manufacturing and maintenance flaws caused a large number of engine failures. Time magazine rated the Triumph Stag as one of the 50 worst cars ever made.
  British Leyland never materially reengineered the Triumph 3.0 litre OHC V8 to address these issues, other than introducing a high-pressure cooling system that boiled over at a higher temperature. Another problem was that the Stag was always a relatively rare car. British Leyland had around 2,500 UK dealers when the Stag was on sale and a total of around 19,000 were sold in the UK over seven years. Thus the average dealer sold only seven or eight Stags during the car's whole production run, or roughly one car per year. This meant that few dealers saw defective Stags often enough to recognise and diagnose the cause of the various problems.
  A number of owners replaced the troublesome engine with units from other cars, such as the Rover V8, or the Triumph 2.5-litre engine around which the Stag was originally designed. The number of such conversions undertaken is not known, but as at July 2017, 91% of Stags known to DVLA ha
caption: 1977 Triumph Stag Mark 2
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