Essay : Not their finest hour – AEC-Leyland 740/800 series V8 diesel
They say that jealousy is never the best policy for politics, a point proven when a well known former Labour Chancellor of the Exchequer was quoted as saying ‘we will tax the rich until the pips squeak‘. The internal politics within British Leyland have always been well documented. The Longbridge management loathed their opposite numbers at Cowley and the Triumph staff at Coventry looked upon Abingdon with envious eyes – it was all pointless bitter jealousy that played its small part in bringing BL quite literally onto its knees.
Who knows what could have been achieved if all parties actually worked in one direction instead of their ongoing and destructive localised inferiority complexes once BL had been formed. At the heavy end of the group Leyland and AEC had been bitter rivals for so many years with its collective ranges of bus and truck chassis. Both makers had staunch loyalty from their customers and both parties being known the world over for their solid and reliable vehicles, even to this day, think of a London bus and a Routemaster comes into mind – built of course by AEC.
Go back 40 years or more and very few hauliers would have ever considered purchasing a Foreign built truck, despite Volvo and Scania – Vabis already having a tiny presence in the UK market. Southall-based AEC had been quietly working on a new range of engines as far back as 1962 to cope with increasing weights and the expanding motorway network in Britain. Their largest power in the truck range was from the 12.5-litre 760 series diesel producing power between 180 and 260bhp but AEC could see that further power extraction required a whole new engine range for future trucks.
Work had started in 1962 on a compact V8 diesel engine of 12 litre capacity with a standard power rating of 250bhp in naturally aspirated form developed at an unusually high 2600rpm. Owing to the large bore short stroke, the V8 was not blessed with huge amounts of low end torque but AEC envisaged that with turbocharging the engine could address this shortcoming. It was also hoped that it could go on to develop 350bhp and beyond once proven. This new engine was proving to be problematic and AEC had held back from signing off the engine for full scale production as they battled to cure some serious shortcomings.
Once British Leyland had formed, the Leyland men visited all the plants to see what new ideas were in the cupboard and once the 800 series engine was public knowledge within the Leyland hierarchy, AEC were pressurized to get the engine into full scale production. The bigger picture of being part of British Leyland meant all divisions were under the cosh to highlight and showcase new ideas – irrespective of the fact if they were simply no good. Test V8 engines had little more than 300 hours running experience and serious shortcomings were noted on the test bench way before any vehicle proving had taken place.
Some very strong opinions and outcries came from the Southall engine designers but British Leyland were having none of it. The engine was pressed into production and was destined to be fitted into the AEC Mandator tractor unit, even more worrying was the fact AEC had just a few months to further develop and prepare the new truck for sale. BL had noticed with the 800 it seemed to have a solution to high power diesel engines yet the engineering quality led approach to manufacturing Leyland were once known was replaced by an inferiority complex. Leyland still viewed AEC as some kind of arch enemy that had to be defeated.
Into production it went and faults appeared right away. Overheating was common and if not spotted quickly enough by the driver, the top piston ring would fail causing the piston to eventually deform and pick up on the cylinder liner rendering all the aforementioned components as scrap. A larger bore engine of 13-litres introduced soon after fared better owing to thinner liners that dissipated heat better. Because of the smooth nature of this engine, drivers would often over rev without knowing and the splitter system of the semi auto gearbox had no interlock to prevent over-speeding in the ratios.
The splitter switch was also very sensitive to the touch and as a result, some drivers blew engines to bits by merely a glancing movement of this switch thus sending rods and pistons though the engine block casting by a result of over revving beyond its capabilities. But drivers loved them and tales of legend were soon banded about recalling stories of fully laden Mandator V8 units passing cars on hilly sections of the A1 – fully freighted. On full song, the Mandator V8 had an engine note almost like a racing car which led some operators to restrict the fuel pump not only to save the engine, but to save the drivers licence too!
Engine strength was compromised too. Because the engine was compact and short in length, the crankshaft bearing journals were much narrower than on traditional in line engines. Many operators found the big end shells were falling between 50 to 60,000 miles which caused customers to bitterly complain. While all this was going on around them, European rivals simply set up their stalls to disgruntled hauliers who simply walked away hand in hand with former AEC and Leyland customers – most of which never returned to a British product.
Even further misery came when Commercial Motor Magazine took delivery of a Mandator V8 tractor from Southall for road test purposes. After collection the vehicle barely travelled a few miles away from the AEC plant when disaster struck. The test vehicle pulled a cylinder liner downwards in the engine block thus grenading the bottom end of the engine. Once a replacement vehicle was sourced, the test went ahead and they commented on the ultra smooth nature of the engine but complained about the lack of torque unless the engine was being worked hard.
Southall engineers worked and sweated to cure the ails of the 800 V8 sadly to no avail and at best gained just tolerable levels of reliability. To get the engine to work properly a redesign of the engine block to extend the crank and bearing surface area would be required. By the early ’70s British Leyland was an open wound hemorrhaging liquid assets – there was simply no money or time to do so. Leyland had by now taken a turn in direction by developing their maximum capacity for minimum cost truck – Marathon and the V8 800 series diesel was quietly and quickly scrapped.
Top AEC engineers had pleaded with Leyland earlier to hold back on production of the engine and certain notable figures within the customer base remained loyal despite this tragic engine but now the solid engineering reputation of AEC was in tatters on a global scale. The 760 in line six engine was subsequently developed into a turbocharged power unit known as TL12 which became a dependable engine of up to 280bhp. Following the closure of AEC and the Southall plant in 1979, engine production of the TL12 moved to Leyland with engineers working on a 350bhp version, but by now all max capacity engines would be bought in and not produced in house.
The 800 series diesel marked a low point in British Leyland and was nothing other than a fatal disaster costing way more than just hard cash. AEC’s public reputation of a once trusted and respected company was destroyed by nothing more than a British Leyland ego trip. A lovely sounding engine that also looked impressive which quite possibly could have been a shining star if allowed to develop. A senior AEC manager once quoted some years later that British Leyland turned AEC from an engineering led company into a Guinea Pig for every hopeless idea that British Leyland could think of.
Moving on to Rover and then PSV / HGV, he has circumnavigated most departments of dealerships including parts, service and latterly - the showroom. Mike has owned all sorts of rubbish from Lada to Leyland and also holds both Heavy Goods & Public Service Vehicle licences, he buys & sells buses and coaches during the week. Mike runs his own automotive web site and writes for a number of motoring or commercial vehicle themed publications