Most of what I know of Leyland’s 0.500 series engines comes from my own (admittedly obscure) interest in the Leyland National bus: permit me a slight detour for a minute…
The National was the (then nascent) National Bus Company’s standard, off-the-shelf product for all its subsidiaries wanting a single-decker at the time, presumably in an effort to standardise fleets and thus cut costs. In its favour, the National was at least relatively well-built and AFAICT “easy” to drive, and parts were supposed to be readily available. Conversely, its rear weight bias, vague steering and rubbish heating took too long to fix. Its biggest single problem, however, was that it came as standard with the Leyland 0.510, the horizontal version of the so-called Fixed-head Wonder. From what I can gather, its design, its location and its orientation meant that essential service routines were skipped, which inevitably led to its reputation as being an unreliable bucket of bolts (if not Leyland’s biggest mistake of all time). Paradoxically, in introducing the Series 2 version of the National (that addressed most of its shortcomings) Leyland used the 0.680, which effectively made it a modern version of the Bristol RE… the same single decker that the national was supposed to replace.
[end of detour]
All that said, I’m curious to know what the 500 series in its applications in lorries was like:
Was it just as big a pile of doo-doo as the bus fraternity made out?
Was it simply the fixed-head design or were there other problems that contributed to its rubbish reputation?
If it really was that bad, why the hell did Leyland even bother with it?
Only contact I had with them was one fitted in a loading shovel we used to service at Tilcons plant in Dove Holes quarry. It did break an external oil feed pipe that was peculiar to the plant application and I had a journey up to Leyland at Chorley to get a replacement but it gave no problems otherwise. Possibly like a CAT engine, more reliable in quarry plant than when fitted in a road vehicle?
I was a Drivers mate at Banbury Buildings in 1971 we had 5 come to coventry depot, I was with a driver that blew 2 of them up, before they were 6 months old, the couldn’t take it if you over run them.
The Leyland 500 Series Engine, or as it was called by a well-known operator (still in business today) “The engine that bankrupted Leyland”.
Whilst it might not have bankrupted the company on its own, it was certainly a contributory factor and its failures ran up a huge warranty claims bill, and it caused a massive loss in confidence by customers in Leyland’s products.
For its time it was an advanced design: - overhead camshaft, timing gear train driven from the flywheel end of the engine, and of course no separate cylinder head. Development started in 1966 with a proposed launch date for about 1969, but the introduction was delayed on a least one occasion, such were the problems encountered in the development phase. The article to which the original poster gives the link is correct in that the engine had to be downsized from its original 700 cu ins to 500 cu ins, but the true reason was that a 700 cu ins it was too big to fit in the Ergomatic cab…I kid you not. The designer, Dr Albert Fogg, had no concept of the eventual applications for the engine. He was an academic, and not a practical engineer.So what was intended to be a high power max weight application power unit was immediately compromised as it’s maximum horsepower was only ever going to be acceptable for 32 tons gvw work. The first applications were not in the Leyland National bus, but in the medium weight Leyland Lynx range where it was used in naturally aspirated guise. And of course, even at 500 cu ins for it to fit the Ergomatic cab the high datum version of the cab had to be used; a 5 inches deep supplementary panel above the wheel arch that looked exactly what it was, that is an afterthought.
In naturally aspirated form in the Lynx the 500 was a bit more reliable than the turbo-charged 510s that appeared in the Buffalo and it was certainly a lively performer. I drove a Lynx and the comparable lorry was the AEC Mercury with AV505, which was no slouch, but the Lynx was livelier (and noisier). The failure rate of 500 engines was unprecedented with any other British built truck, either before or since. The Leyland dealerships could simply not keep up with warranty claims and replacement engines were always in short supply. A situation not helped by the fact that the Leyland engine production line had a 30% rejection rate of 500 series engines, such was the complexity of the assembly that tolerances simply could not be met on many engines and they could not pass QC examination and test running. The quote at the beginning of this post was said to me by an operator who bought 10 Buffaloes and within the first month of service 7 had blown up.
The 500 fixed head engine was too radical a design for the mid-1960s and the production of the unit was complex for the technology available at the time. It cost Leyland dearly, not only financially, but in the longer term the loss of customer goodwill, and ultimately customers. It was without doubt the biggest engineering disaster ever suffered by a major truck manufacturer.
It would seem it progressed like the 740 and 800 series vee eight.Let the customer do the testing.Besides the TL12 which is well thought of,the rest seemed to be plagued with issues that were really uncomplicated to rectify.By my way of thinking the starting point should have been to mount a cabin that was high enough to get a decent sized radiator and some air flow around the engine.
The problems with the 500 Series design and manufacture went far deeper than overheating, which wasn’t too much of an issue. The OHC design made it a tall engine. It was a high revving unit, 2,400 rpm maximum. Leyland as we know was strapped for cash by the early 1970s so as with the Marathon a new cab wasn’t an option. Besides which a long term contact had been agreed with Sankey (later GKN Sankey) in 1965 for the supply of a minimum quantity of Ergomatic cabs. I know that AEC alone was contracted to take 30,000 cabs, which they did and used them all by 1977. I don’t know what the figures were for Leyland and Albion. Various engine modifications, 502, 510, 511, were attempted, but Leyland had to abandon the design in late 1976, replacing it with options of the L12 and TL11A, (basically a hastily reworked and turbo-charged O.680). When driving a 500 powered lorry such was the reputation that you expected it to blow up at any minute, and when they let go they did so dramatically.
gingerfold:
The problems with the 500 Series design and manufacture went far deeper than overheating, which wasn’t too much of an issue. The OHC design made it a tall engine. It was a high revving unit, 2,400 rpm maximum. Leyland as we know was strapped for cash by the early 1970s so as with the Marathon a new cab wasn’t an option. Besides which a long term contact had been agreed with Sankey (later GKN Sankey) in 1965 for the supply of a minimum quantity of Ergomatic cabs. I know that AEC alone was contracted to take 30,000 cabs, which they did and used them all by 1977. I don’t know what the figures were for Leyland and Albion. Various engine modifications, 502, 510, 511, were attempted, but Leyland had to abandon the design in late 1976, replacing it with options of the L12 and TL11A, (basically a hastily reworked and turbo-charged O.680). When driving a 500 powered lorry such was the reputation that you expected it to blow up at any minute, and when they let go they did so dramatically.
Can’t do the technical thing Gingerfold, n till recent I didn’t know the speed of a piston!! I lost 2 500 engines, one ticking over in a S Wales brick yard ,tother south of Northfield on the A38 ,the engine spewed onto the road. So one died in it’s sleep the other was a little more dramatic. But when they went well they went well
gingerfold:
The problems with the 500 Series design and manufacture went far deeper than overheating, which wasn’t too much of an issue. The OHC design made it a tall engine. It was a high revving unit, 2,400 rpm maximum. Leyland as we know was strapped for cash by the early 1970s so as with the Marathon a new cab wasn’t an option. Besides which a long term contact had been agreed with Sankey (later GKN Sankey) in 1965 for the supply of a minimum quantity of Ergomatic cabs. I know that AEC alone was contracted to take 30,000 cabs, which they did and used them all by 1977. I don’t know what the figures were for Leyland and Albion. Various engine modifications, 502, 510, 511, were attempted, but Leyland had to abandon the design in late 1976, replacing it with options of the L12 and TL11A, (basically a hastily reworked and turbo-charged O.680). When driving a 500 powered lorry such was the reputation that you expected it to blow up at any minute, and when they let go they did so dramatically.
Agree with that,the TL11 was an absolute pig of an engine that really shouldn’t have been and most of its troubles was put down to poor cooling.
Never had a Fixedhead engine but ran a Constructor with a TL11 engine never had any problems with it as regards cooling did have a timeing gear shatter and that was the only problem . The Constructor flatbed was a 2421 with a Fuller box
gingerfold:
The problems with the 500 Series design and manufacture went far deeper than overheating, which wasn’t too much of an issue. The OHC design made it a tall engine. It was a high revving unit, 2,400 rpm maximum.
Seems strange as to why the article only seemed to concentrate on the theoretical benefits of the design while not explaining the failure of previous fixed head designs.
Which also raises the question of how do they explain the directly opposing approach of seperate removable heads combined with pushrod design and high torque low engine speed still found in the modern day Scania ?.When it’s clear that the latter not only provides the required durability but also the best possible facility for maintenance.
gingerfold:
The problems with the 500 Series design and manufacture went far deeper than overheating, which wasn’t too much of an issue. The OHC design made it a tall engine. It was a high revving unit, 2,400 rpm maximum.
Seems strange as to why the article only seemed to concentrate on the theoretical benefits of the design while not explaining the failure of previous fixed head designs.
Which also raises the question of how do they explain the directly opposing approach of seperate removable heads combined with pushrod design and high torque low engine speed still found in the modern day Scania ?.When it’s clear that the latter not only provides the required durability but also the best possible facility for maintenance.
But it doesn’t.
Scanias latest 13litre suffers badly with liners fretting in the block,rendering the block scrap in certain cases.It also suffers with the block face creeping away as the heads move around.This is mainly due to not having a one piece head as support to the block.Again it suffers from oil leaks at the bottom of the block were it cracks in line with any 7 of the main housings.
Were the torque comes from is the XPI fuel system and SMART VNT turbocharger.
Carryfast:
Which also raises the question of how do they explain the directly opposing approach of seperate removable heads combined with pushrod design and high torque low engine speed still found in the modern day Scania ?.When it’s clear that the latter not only provides the required durability but also the best possible facility for maintenance.
But it doesn’t.
Scanias latest 13litre suffers badly with liners fretting in the block,rendering the block scrap in certain cases.It also suffers with the block face creeping away as the heads move around.This is mainly due to not having a one piece head as support to the block.Again it suffers from oil leaks at the bottom of the block were it cracks in line with any 7 of the main housings.
Were the torque comes from is the XPI fuel system and SMART VNT turbocharger.
That obviously isolated example doesn’t seem to make any difference to the basic premise,as to the relative impracticality regarding maintenance of the OHC/CIH one piece head,let alone fixed head,as opposed to seperate heads and pushrods and general durability of same in everything from Mercedes to Scania V8 and even to an extent the 14 litre ■■■■■■■■ three piece head design.While the 500 being a typically highly stressed small capacity torqueless screamer just predictably added to its durability problems possibly moreso than just its monobloc design.
Carryfast:
Which also raises the question of how do they explain the directly opposing approach of seperate removable heads combined with pushrod design and high torque low engine speed still found in the modern day Scania ?.When it’s clear that the latter not only provides the required durability but also the best possible facility for maintenance.
But it doesn’t.
Scanias latest 13litre suffers badly with liners fretting in the block,rendering the block scrap in certain cases.It also suffers with the block face creeping away as the heads move around.This is mainly due to not having a one piece head as support to the block.Again it suffers from oil leaks at the bottom of the block were it cracks in line with any 7 of the main housings.
Were the torque comes from is the XPI fuel system and SMART VNT turbocharger.
That obviously isolated example doesn’t seem to make any difference to the basic premise,as to the relative impracticality regarding maintenance of the OHC/CIH one piece head,let alone fixed head,as opposed to seperate heads and pushrods and general durability of same in everything from Mercedes to Scania V8 and even to an extent the 14 litre ■■■■■■■■ three piece head design.While the 500 being a typically highly stressed small capacity torqueless screamer just predictably added to its durability problems possibly moreso than just its monobloc design.
Have a conversation with your local Scania agent.Ask them what their most busiest with,its a problem that is far from isolated.
What have Mercedes benz done with their engines of now?Switched to Detriot all with single piece head,■■■■■■■ have mainly been single pieces for a very long time.The vee eight Scania being the exception,they have their reasons.Iveco,volvo all single piece.Its for a good reason.If trained accordingly the maintenance is no more difficult than single heads.
Carryfast:
That obviously isolated example doesn’t seem to make any difference to the basic premise,as to the relative impracticality regarding maintenance of the OHC/CIH one piece head,let alone fixed head,as opposed to seperate heads and pushrods and general durability of same in everything from Mercedes to Scania V8 and even to an extent the 14 litre ■■■■■■■■ three piece head design.While the 500 being a typically highly stressed small capacity torqueless screamer just predictably added to its durability problems possibly moreso than just its monobloc design.
Have a conversation with your local Scania agent.Ask them what their most busiest with,its a problem that is far from isolated.
What have Mercedes benz done with their engines of now?Switched to Detriot all with single piece head,■■■■■■■ have mainly been single pieces for a very long time.The vee eight Scania being the exception,they have their reasons.Iveco,volvo all single piece.Its for a good reason.If trained accordingly the maintenance is no more difficult than single heads.
I meant isolated in the sense that there is no conclusive link between seperate heads and un reliability in the numerous examples shown.
While I was only referring to the example of the opposite extremes of fixed head OHC v pushrods and seperate heads regarding maintenance.While single head or not major engine work is going to take more time and aggro in the case of single head and OHC/CIH than even single head and pushrods.While going for a fixed head OHC design effectively makes the engine uneconomic to overhaul which seems to have been confirmed in the case of the 500.Which notwithstanding the issues of OHC/CIH v pushrod design is probably why no other manufacturer has gone for the fixed head option.
Carryfast:
That obviously isolated example doesn’t seem to make any difference to the basic premise,as to the relative impracticality regarding maintenance of the OHC/CIH one piece head,let alone fixed head,as opposed to seperate heads and pushrods and general durability of same in everything from Mercedes to Scania V8 and even to an extent the 14 litre ■■■■■■■■ three piece head design.While the 500 being a typically highly stressed small capacity torqueless screamer just predictably added to its durability problems possibly moreso than just its monobloc design.
Have a conversation with your local Scania agent.Ask them what their most busiest with,its a problem that is far from isolated.
What have Mercedes benz done with their engines of now?Switched to Detriot all with single piece head,■■■■■■■ have mainly been single pieces for a very long time.The vee eight Scania being the exception,they have their reasons.Iveco,volvo all single piece.Its for a good reason.If trained accordingly the maintenance is no more difficult than single heads.
I meant isolated in the sense that there is no conclusive link between seperate heads and un reliability in the numerous examples shown.
While I was only referring to the example of the opposite extremes of fixed head OHC v pushrods and seperate heads regarding maintenance.While single head or not major engine work is going to take more time and aggro in the case of single head and OHC/CIH than even single head and pushrods.While going for a fixed head OHC design effectively makes the engine uneconomic to overhaul which seems to have been confirmed in the case of the 500.Which notwithstanding the issues of OHC/CIH v pushrod design is probably why no other manufacturer has gone for the fixed head option.
Its a known fact a one piece head stiffens the block face,this reduces flexing and liner fretting,thats why nearly all are now single piece.As for maintenance every OHC engine ive been involved with(D20,D13,Cursor,ISX)the camshaft has been left in to remove the head.Valve clearance set up is easier because the inner base is viewable on the camshaft.In certain cases less head bolts,and to top it all off ease of removing the camshaft unlike an OHV set up.In essence the 500 had a good spec but the technology to produce the block wasn’t available.
Perhaps there were two trains of thought being followed with the 500 engine. Leyland were returning to their roots with an overhead cam, single head design and at the same time seeking a solution to the head gasket failures which were plaguing not just them selves.
cav551:
Perhaps there were two trains of thought being followed with the 500 engine. Leyland were returning to their roots with an overhead cam, single head design and at the same time seeking a solution to the head gasket failures which were plaguing not just them selves.
The headgasket failures could have been rectified without going to the 500 design.
