Welcome to the forum.
I'm sure there's plenty of anecdotes along these lines but you'd imagine if the problem was so bad in comparison to things they replaced there would be published figures to show they were inferior to what they replaced however I'm having a hard time finding any, so is it that they were unreliable in comparison to the things they replaced or just unreliable in comparison to other diesel types of the time? If its the former then their reputation as bad is perhap somewhat unearned as they would still represent a saving of hours and step up in working conditions for crews on them just not be quite as good as the other types coming in.
There wouldn't have been published figures at the time, but lots of the British Railways internal documents survive in the National Archives at Kew. Fortunately for you Anthony Sayer has already done the research, and published lots of the data in his book.
I shall hunt the book down but again if it only contains data on the Claytons and not the things they pushed aside then it doesn't really answer the question of comparative reliability, we're already seeing perhaps a hint at a causative factor in the figures being lack of appropriate maintainance facilities compared to the diagrams they were put on making any issues more time consuming and troublesome to deal with since a loco could have an issue that perhaps with a steam equivalent could be rememdied on shed at any number of locations where as the expertise and resources were isolated to a couple of sheds for the Clayton.
That's the rub of it, all very good points. To get a clear picture one has to have access to the loco diagrams concerned, both pre Clayton, and for the Clayton's themselves, at say, the time table date when the entire class was commissioned, which looks to have been roughly in numerical order, 8616 arriving new at Barrow Hill in April 65. Given their introduction would likely have involved a degree of pre planned changes to both existing loco diagrams and crew rosters in readiness for their arrival, a clear picture is very hard to pin down me thinks!
I wasn't there at the time, but having worked on the job, I do wonder if a lot of this sort of sentiment has over the years come from the enthusiast side of the fence? On the subject of Claytons and Barrow Hill/Staverly sheds, I did once hear that the steam guys there at the time, once having got their hands on their new toys (17's), couldn't get rid of their old steam mounts fast enough - they could actually go home at shift's end with overalls and themselves still reasonably clean. I suspect this is true of many who went through the steam to diesel/electric transition, even if saying so (even this far after August 1968) still causes a sharp intake of breath in some quarters....!
I have just dug out the companion volume for the class 15s/16s which I do have (my purchase choice was/is a 30A - Stratford thing!). It does include tables showing % availability by week/period for various dates based on 24 hour averages with average weekly mileages, all by type/number of units on strength, not by individual painted number. In the case of these, there is a one page 'High level summary of operations' - much of their early work was replacing steam on cross London freights and internal (ER) trip workings based at the likes of Kings Lynn, March, Norwich, Ipswich, Finsbury Park. So the types (of steam loco) replaced will have been many and varied - from my own personal interests, I know Devons Road, Bow, used a good many Jinty 0-6-0T's until they were displaced by class 15/16 in basic terms, which is the closest comparison that springs to my mind - as for Jinty availability?
The justification for dieselisation was that their supposedly greater availability compared with steam justified the higher capital cost. (I recall seeing a figure of 22 Deltics replacing 55 Pacifics, although some of those savings were the result of reduced journey times allowing more round trips in a day per loco). Thus the expectation was that Claytons would be more available than the steam locos they replaced. It would nevertheless have been disappointing if they were, say, 10% more available if they had been expected to be 30% better.
Both books refer to fleet availability data from a National Traction Plan (NTP) "Progress report and assessment of position at 18 April 1966".
Whilst I don't doubt they had better availability than UK built locos they also likely had a different maintenance regime which must have helped to some degree?
99.8% availability suggests that each locomotive was only unavailable for 15 hours a year, which seems unlikely. Perhaps the figures do not count scheduled maintenance.
That assumption, 99.8% excludes scheduled maintenance, makes sense.
Really depends but there are a lot of issues you'll just make worse by soldiering on which can represent a bigger turnarount on any repair so it's best in either case to stop. A lot of things you should stop for at the nearest convenient point due to safety reasons may also be overlooked by some since there was no real recording method of when the fault developed so you could just say it happened towards the end of the trip in some cases. People were not and even today are not always as professional as we may imagine hence the presence of recording devices these days to keep an eye on what is going on.
As said above, would depend upon circumstances. Two major steam related failures of some magnitude that spring to mind from memory of reading about same, are one involving MN 35020 at Crewkerne, when a bent/detached con rod caused a major failure, and some parts (of the motion of the loco) flew off and demolished part of the station canopy as the train passed. The other was a blow back involving an 8F (48660???) running southbound at Midsomer Norton, when (to put it simply) the footplate was engulfed in boiling steam/water and the crew, who I think both survived, suffered horrendous scalding/burns as a result. As said, this is from memory of reading of same, so I can't be more detailed at this moment.
That's not always the case. On a diesel locomotive the cooling system may shut down the power unit to prevent serious damage from overheating. Auxiliary equipment failures such as compressors or exhausters can prevent release of the brakes.
Was it not the crankcases rather than the heads?
You may be correct, I couldn't remember.
For some ideas on what used to be possible, the section on valves in the BTC Handbook for Railway Steam Locomotive Enginemen is instructive. Lots of Q&As about how to deal with breakages and other failures of various fundamental parts of valve gear etc, mainly with the aim of being able to continue operating with the loco working on one side only. Anything to avoid having to summon another loco for assistance!
BTC is instructive about using a spare fishplate or even a coal pick to lift a loco sufficiently to enable packing to be inserted above an axlebox where a spring has been broken or lost. It is suggested that this type of field surgery is only carried out if the problem occurs at "a considerable distance" from an MPD, and then ideally under the protection of fixed signals. I haven't found anything for tender wheels yet.....
