Engines : S-Series
Another evolution of the E-Series engine, ARG’s S-Series emerged capable and strong, and proved a remarkably capable mid-range power plant after a false start with the R-Series ‘hybrid’.
Mike Humble tells the story of an engine killed before its time.
The forgotten mid-sized engine
Launched in 1984, Austin Rover’s new S-Series engine first saw the light of day in the Austin Montego, although prototype engines had been running as far back as 1981. The original idea had been for the Maestro to receive this engine back in 1983, but owing to a lack of cash, factory disputes and the technology not yet proven, it was decided to hold back until engineering were satisfied the engine was developed thoroughly for full scale launch.
With the launch coming up for the Maestro, BL knew it had no suitable mid-sized 1.6-litre engine, and had to work fast to come up with a suitable power unit, if it was to hold its own against Ford’s Escort and Vauxhall’s Astra. The Maestro was launched to the public with the R-Series 1598cc engine, that was simply an E-Series 1750 Maxi engine rotated through 180-degrees, mated to a Volkswagen gearbox, and bored down to a 1.6-litres configuration. The engines sported electronic carburettor control which regulated the idle speed and choke, along with an overrun fuel cut off, all contributing to improving fuel economy and driveability.
The R-Series was flawed in many aspects. Because the Maxi had a transmission-in-sump and the Maestro used the bought-in Volkswagen ‘box fitted end-on, the bottom-end of the engine became weak. Austin Rover overcame this by fitting a huge cast alloy sump that was an extremely expensive casting to produce, so much so that an insider commented that it contributed to 20 per cent of the total raw cost of the engine!
This reworked engine shared many similar features with the older E-Series engine, noisy timing chains, an appetite for burning, blowing head gaskets and one particular good trick of breaking crankshafts. Power outputs were 81bhp in single SU carburettor form and 103bhp in twin-Weber MG tune. The word ‘tune’ being loosely used, as these MG Maestros were notorious for poor running, overheating and forever going out of tune. In standard single-carburettor form, the engine had acceptable performance and economy, but was harsh when pushed. But this engine was at the end of its development and was seen to be nothing more than a stopgap. The car’s reputation was already suffering at a mere 18 months into its life.
Enter the S-Series in 1984
Launched in 1984, the Montego featured an all-new 1600cc S-Series power unit alongside existing 1275cc A-Plus and 2.0-litre O-Series engines. It sported modern day refinements such as electronic ignition and a belt-driven overhead camshaft. Great efforts were made to reduce service downtime. For example, its simple timing belt arrangement allowed a belt replacement in 30 minutes, no tools were required for air filter changes, and a major service could be undertaken under the bonnet using no more than five tools.
Performance was equal to Vauxhall’s Cavalier 1.6, and was simply streets ahead of the Ford Sierra 1.6. In Montego form 0-60mph came up in 10.9 seconds; more than 2 seconds quicker than an equivalent Sierra. Fuel economy was class-leading too with over 53mpg at the constant 56mph cycle – and even at a constant 75mph, the 1.6 Montego was capable of almost 40mpg. These figures were even more impressive in the lighter Maestro 1.6, which also received the new engine.
Many revolutionary technical features were included in this engine, such as electronic knock-sensing, programmed ignition, electronic fuel control and an ingenious pre-heater fitted to the inlet manifold (known in the company as the ‘hedgehog’ owing to shape of the heating elements) to reduce cold engine emissions and reduce the warming-up period. To combat the problem of mechanical harshness of the previous R-Series unit, Austin Rover powertrain engineers paid attention to developing a stiff bottom end of the engine, with generous bearing areas and an eight-web fillet-rolled crankshaft to eradicate harmonic vibrations that were the cause of some crank failures of the previous engine design.
Austin Rover continued the theme of long-stroke design, offering ample torque, and in BL tradition, it had both the inlet and exhaust manifold on the rear of the cylinder head giving the engine a clean and uncluttered underbonnet look. The single belt-driven camshaft operated bucket-type tappets with shim adjusters. Both the engine block and cylinder head were of cast iron, but the separate camshaft carrier was cast in alloy with two matching alloy valve covers.
The single SU HIF44mm carburettor was fitted with a smart looking polished alloy plenum chamber proudly sporting the Austin Rover Group wing logo. It was a sleek and slim looking engine that was a world apart in appearance of the big bulky Ford OHC Pinto used in the Sierra. One clever idea was the engine being a safe design (i.e., the valves did not come into contact with the pistons in the event of a broken timing belt), unlike the Ford CVH & Vauxhall Family Two OHC units.
Mid 1985 saw the Rover 213 gain his big brother, the 216. Though where the Maestro and Montego were fitted with a four- or five-speed VW gearbox, the S-Series was adapted to accept the slick-shifting new T5AR gearbox, as fitted to the 2.0 Montego (engineers thought the gear shift quality of the VW box to be too agricultural for a Rover. A four-speed automatic option was available on the 216.
At the same time, the S-Series engine was offered with fuel injection in the 216 Vanden Plas EFi and Vitesse models. They used a Lucas-engineered system similar to the type fitted the 2.0-litre O-Series injection cars. These were only car in the Austin Rover range to use a 1.6 injection S-Series. This fuel injected engine offered decent performance with the smallest of penalty in economy, in fact on the urban cycle the injected 216 was more than 2mpg better. Why this uprated engine was never fitted to the Maestro and Montego remains a mystery.
The first major update of the S-Series was launched at the 1988 motor show, and with hardened valve seats could accept unleaded petrol. The main feature was a revised and up to date modular engine management with diagnostic fault code storage combining all under bonnet electronics into one unit as opposed to the original two. This system was known as ERIC, which stood for Electronically Regulated Ignition and Carburetion. Designed as a joint effort between Rover and Motorola at the Gaydon technical centre, this new type of learning modular ECU became the basis of all future Rover management systems, and was an excellent reliable system finally putting to bed earlier reliability issues.
On the road and in the bays
At its initial launch, the 1.6 was lauded in its performance, fuel economy and ease of repair. Some might say that it very nearly could have become the ideal engine, certainly from a mechanic’s point of view. The whole idea of the Montego was to appeal to the fleet buyer as well as the man on the street, and on paper this new British saloon was looking like a very attractive proposition being fast, roomy, nimble and very economical. But as history has shown time and time again, the car and its engine gained a reputation (slightly unfairly) for unreliability and poor quality.
As mentioned earlier, the S-Series was designed to be simple, economical and easy to work on. It was very much designed with a service technician in mind. On the other hand, Austin Rover made some silly design features that in some cases flew in the face of the other really innovative ideas and features that were part of this engine – and gave the power unit a reputation that never really went away.
It was notorious for oil leaks from the camshaft carrier and valve covers, and the engines tappets would always sound noisy even when within tolerance. The top end of the engine would make a nasty rattle through oil starvation if pattern fit oil filters were used – left ignored, this caused horrendous wear to the camshaft and its carrier. The crankcase breather system was also a poorly designed affair, mounted on the bottom of the front of the sump. This would cause the system to block because of cold air coming through the bumper grille caused condensation in the breather can giving symptoms similar to a blown head gasket because the oil filler cap was also part of the breather and would readily block up with mayonnaise type sludge.
The main problems of oil leaks from the top end of the engine were caused by the face to face fit of the cam carrier to cylinder head joint. These two parts had no gasket fitted; instead the sealing was done by a non setting gasket compound that often was not applied correctly on assembly. Also, the oil gallery in the cam carrier was sealed by a single 8mm O-ring. These were found to be non compatible with oil on early engines resulting in the ring hardening and cracking causing a massive oil leak, left unattended would contaminate the timing belt and cause it to snap.
Other issues included faulty ECUs on earlier cars that caused the choke to stay on and give poor running; faulty crankshaft position sensors that gave misfires and limited revs. Another major problem was the left hand cam cover was prone to crack, owing to the stress of the manual fuel pump being bolted to it.
Most of these issues had been resolved by 1988, but by then the game had moved on. The Maestro, Montego and the S-Series engine were living on borrowed time following the launch of the highly successful revised 200 and 400 range using state of the art K-Series and Honda D-Series engines. Looking back, the S-Series wasn’t a bad engine by any margin; its reputation was tarnished by the motoring press from day one never giving Austin Rover a chance to prosper, something that continued to the very end. What a lot of people don’t realise is that the engine and the Montego were developed at a cost of 1/5th of the cost of developing the Sierra and the Mk2 Cavalier.
Having owned both 1.6- and 2.0-litre Montegos, I still can’t decide which was the better unit. The 2.0-litre was tough and gutsy, but thirsty, but the 1.6 sounded nicer, was only marginally slower but gave superb fuel consumption. Looked after and serviced correctly, these engines were capable of 200,000+ miles, I regularly would see later fleet Montegos with silly mileages still running sweetly.