Total so far this year 4!

An AEC engine with All-4-Event in Germany suffered overheating problem in July; engine seized. I got another engine for it form a customer in Amsterdam, it sounded really sweet. That lasted 4 weeks, overheated and seized. Probably caused by a blocked radiator and a very hot summer. I'm waiting for another engine from Ian in Newark, and a replacement radiator!

News by email today of a Leyland engine RM in Italy (German registered) with a piston out of the block; no chance of Leyland spares these days.

And this evening, from a customer in Antwerp with a Northern RM (AEC engine)has also had a rod out the side this week!!

I understand another RM engine blew up on a motorway here the other week?

As there seems to be a dearth of AEC and a total lack of Leyland parts, it could be the much awaited cull of RMs is about to happen unfortunately.

My bus number (if any): RML2532

It's quality of parts that will be the problem.

18 or so years ago, maybe a lot more! , I recall stillages of AEC and Leyland engine parts that vanished from Chiswick.

No-one was too bothered as all the missing pats were rejected as sub-standard and were supposed to be returns.

As by then, engines rebuilds were being contracted out and Chiswick coming to an end, no-one seemed to care.

But I do know that years later, those stillages surfaced in several places, several at a bankrupt reconditioners receivers auction.

One can only assume that those below par components have found their way into the parts supply chain and short of accessing the records for production numbers and IDs, which is probably now impossible, there's no way of knowing.

It's not all bad news. There are a lot of specialist and low volume machinists and fabrication businesses who can produce engine components to fine tolerances. ND use a few in Poland who are very good and there are some in the UK.

It comes down to a collective of some sort - Probably the RMOOA to identify the shortages and needs. Seek out the drawings and specs and work together to find a solution for production.

That is probably harder than the actual remanufacturing itself.

There's been a general shortage of Leyland 600 parts for years as they were never a popular engine in London.

I reckon the recent spate of failures has been caused by a combination of a very hot summer in northern Europe, some days up to 35c; blocked radiators causing overheating; broken fans (at least 2 engines I know have at least 1 fan blade missing), old age and a lack of preventative maintenance. all thee are also not helped by LT buses not having oil gauge or temperature gauges.

While that was ok when they were in London (engine blow up, tow to garage, fit another engine, back on the road tomorrow), it's no good for those whose living relies on a promo bus trucking the length of Europe for the next job.

I forgot to ad the RT engine that packed up in north Germany as well! Grrrrr.

I've found a firm who can make cylinder liners providing we can provide a sample; pistons I have in stock for RT/RF and a few RM bits; head gaskets for AEC590 are in very short supply; valves are in stock...it's not easy or cheap these days to rebuild engines.

My bus number (if any): RML2532

I know this will not go down very well but surely instead of spending small fortunes on existing AEC / Leyland engines why not explore the substitution by a modern diesel engine to those vehicles which are used more often. There are many Routemasters with non original engines, why not RT's as well if it means they can be used efficiently, especially if still earning a living on H&R.

Seems to be the preference now for PH work and longer distance work.
But properly maintained and correctly set up, and AEC or Leyland unit should last for a very long time.

Simple things like water, radiator & hose conditions and the fan are things that anyone taking a bus out on the road should check, every time. Just like the lights and brakes and so on.

But these buses were designed and set up for a specific purpose. Stop start low speed operation.

Other AEC and Leyland engines for other sorts of vehicles were set up for different uses and all the adjustments and alternative ancilliaries did exist for long distance running, higher gear ratios, differentials and so on.

For PH outside of London or regularly using an RM over long distances, Probably the better option is to set the vehicle up as per the RCL or RMA types.
A combination of different ratio differentials gear timings, and engine capacities can alter the characteristics of the vehicle and whilst wind resistance will impede any serious increase in speed over safety, it will reduce wear and tear on components that are being overstressed from useage that was not intended.

It needs careful thinking and calculating and my old mentors phrase "Horses for Courses' rings through my head.

None of these options are easy any more, but our engineers have come up with sourcing all sorts of solutions when in a tight spot and the 'factory component is not available.

The answer is to try to source Cummins engine vehicles for this sort of work. Oddly enough the customer bought RML2567 a while ago, never used it and sold it to someone in Cologne. It would have been a sensible option to convert that for his long distance stuff but cash flow dictated it had to go to try to keep the others going.

My bus number (if any): RML2532

The AEC AV 590 was an early 1950s design and the Leyland 600 is even older.Apart from railway and industrial use the main 'other' vertical automotive application was for heavy lorries. The speed limit for such vehicles at the time was 20 mph, not many of the vehicles that were fitted with these engine were capable of achieving much more than just over 30 mph anyway. There were no motorways so every journey was across country with constant changes in speed and load. Even so, and in spite of the far more frequent and extensive maintenance schedules of the time, these engines were not regularly exceeding 200,000 miles before becoming worn out. Many that even got that far were like Trigger's Broom having had various components renewed. Move on to the beginnings of the motorway era and the constant over-speeding and flat-out full load running gave them severe indigestion. Matters never improved with the upgrades and evolutions of both engines only coping marginally better. Both manufacturers tinkered with designs increasing revs and squeezing more power, but in practice merely shortening the ultimate life of the engine. It is hardly surprising that survivors of an obsolete design are failing regularly, since both engines had been withdrawn from mainstream production by the mid '60s. I can't recall any new AEC lorries with AV 590 engines post 1965 and the Leyland 600 only outlived it by a couple of years.

I have to admit that I had not considered that although I did think that late AEC trucks still used 690 combinations as did a few late leyland trucks which could do up to 60 on motorways.
The BEA RMs ran very well on the M4 even with the swaying trailers (improved in later years)

With so many huge improvements made to diesel engines over the last 10 years in particular, I would love if resources were to hand, to take an AEC and Leyland unit and see what can be done to radically improve them.

The actual lump is not radically different from a very modern engine but well over engineered but the differences are with almost all the other 'ingredients'.

Lightened components made from stronger newer metals, more efficient bearings, everything fully balanced and so on.
Improved sump and pump ancilliaries .Same with the heads.

I think it could produce an engine that will run more efficiently but would be more robust.

To do a one off development engine would cost an arm and a leg. One for a euro millions win.!!
That said, once one is done. Tried tested and adjusted, once a spec and parts are sourced and fabricated, subsequent rebuilds would be little more than current full rebuild.

I vaguely recall that the LT research lab at Chiswick had taken several badly worn AEC and Leyland units and carried out a huge amount of updating and performance related modifications. Some of which were to be factored into overhauls. This was in the late 1970s early 80s and never went ahead. I think it was in conjunction with AEC just before they closed
Engines did not come into my domain much so I did not take an interest at the time. Wish I had now.

Hopefully someone does know a lot more, maybe even the specifications and mods are documented and sitting in a file at the LTM.
Being in Qatar right now means I won't be popping in there for a while but maybe it does hold a key to a few solutions.

The problem is now that all new build engines have to be to Euro6, so in my view a modified AEC or Leyland is not the answer. the blocks, heads and everything must have been stretched to the limit by now as both roy and myself have seen quite a few recently with sever cases of metal fatigue.

ISTR AEC making a turbo version of the 760, but was beaten to the post by its closure and the development of the Leyland TL11 which in my view was quite a good engine.

My bus number (if any): RML2532

Surely the advice to all preservationists running RM's (or any other preserved vehicle not fitted with a low oil pressure gauge and/or warning light) has to be to fit a gauge and to keep a close eye on what it is telling you. And don't ignore the warnings if you are really serious about keeping your vehicle on the road indefinitely.

That way it may be possible to take some remedial action...anything from using a slightly thicker engine oil (20W50?)to give a slight but significant increase in hot oil pressure, to fitting new remanufactured main bearings) before the engine blows itself apart.

Incidentally one of the Leyland 0.600 vertical engined vehicles I work on has just managed to bust both the inner and outer valve springs on number 3 exhaust valve...and not drop the valve down the hole! Lucky or what!

My bus number (if any): Nothing beginning with RM, yet!

That's a really good point.
Fitting a set of gauges would be a very shrewd and positive means of preventative maintenance.

Oil pressure and temp, Water temp, fuel level, charging, and gearbox pressure.

All these are fitted in modern trucks and probably buses ( although I've not looked)

Most have a digital display which takes up a small area but the sensors for each gauge are pretty much fitted as they always have.

Maybe someone who has done this could write a piece about where to locate sensors and how to connect these into the electrical system correctly.

If you follow, as we do, the recommendations in the AEC manual for the engine/chassis, little can go wrong. It's not hard to check the oil and water is it? We do it at least daily and carry a large bottle of water, engine oil for engine and compressor in every bus, fits in a little box under the stairs. Trouble is too many people are used to sealed water systems and have got out of the habit of checking the oil.

My bus number (if any): RTL 960, RMC 1458 RM 1585, (M 961, M 271 - both sold) and several RTs

Hi....Years ago when two RMs per day were driven to what is now Volvo at Nottingham 120 miles or so for engine changes, quite a high proportion of units failed on the journey. During a conversation with the Works Manager he questioned the suitability of the AV590 for this distance flat out running. The removed AEC units were lined up in droves in the yard, all fully dressed, many re-conned with the paint hardly dry! What a sight, and almost all went to scrap. Ian.

My bus number (if any): rm446

This interesting thread raises important issues on preserving our ageing AEC engines.

I'm fitting a Quadbike/Motorcycle computer to one of my AEC AV590 RMs that will display engine revs, speed, water temperature, oil pressure, voltage and fuel tank level. Warning lights and/or audible alarms can also be fitted. The unit includes sensors (except fuel tank sensor) and cost about £150.00

I've seen it working on the Swedish railcar (Scanis Vabis engine/SCG "Wilson" gearbox/28 volt electrics) at Nene Valley Railway.



It seems to do everything it says on the tin.

I need to decide where and how to fit the oil & temperature sensors. The revs and speed sensors will be bracketed to pick up signals from a rotating magnets before and after the gearbox.

The unit is "road legal", complying with ECE regulations and can be used as a speedometer.

I've just got it and will report progress on fitting it as the task evolves.

Where do I put the water temperature and oil pressure sensors?

My bus number (if any): RMs 238, 471. 2213 & GS1 7

The water gauge should be connected to the rear cylinder head thru a small bolted plate at the back of the head and facing you as you stand at the side of the engine bay. The plate will probably be plain and flat but if you are lucky you might find a subsitute with an adaptor already fitted to take a connecting pipe. Afraid I don't know where the oil pipe is connected.

My bus number (if any): RM1001

One of the German engines had the temp sender in place of a drain plug in the side of the block just above the fuel pump. As to oil pressure, you may need to modify the oil filter housing (if a filter is fitted).

On the RF engines, there's a blanking plug on top of the pump drive gear housing that I've used for the purpose. On the GS Perkins engine, there's a blanking plug on top of the oil filter housing. My GS runs at 70psi, dropping down to about 50psi when hot!

The idea Chris has got from the NVR sounds like a good idea. Jut make sure it doesn't involve connecting anything negative to the chassis, or you then have the possibility of negative earth to body and gearbox problems...

My bus number (if any): RML2532

In order to connect an oil pressure gauge, remove one of the 1/8" BSP plugs from the oil gallery on the o/s of the engine if there is an oil filter fitted, or if there is not, to the wired connection where the filter would otherwise be found.

Heat rises so the coolant drain plug at the base of no 6 cylinder is not a good place to fit a coolant temperature transmitter.

Do not forget that the lighting circuit for any auxiliary gauges also needs to be insulated earth return so chose the gauges themselves carefully.