cargo:
It would seem a common engineering problem.
Our 680 and 690’s would pull head studs, silly fine BSF thread into the cast iron block and way too short on depth.
We would drill/tap to larger diameter Whitworth with much more depth into the block. Machine up stepped studs and from then on no head gasket or stud problems.
I can understand how most operators would just walk away.
Very disheartening when a brand new 690 pulls studs by its first service.
The 470 had a “soft” crank rep in Aus, whereas the Leyland stuff with nitrided crank was bullet proof.
I think the 505 went to a nitrided crank??
Certainly the headless wonder had a nitride crank, another speciality of Leyland was to supply new vehicles with Cranks that had already been reground.
Cav we had some 680 blocks that were a throw away.
On the left side it’s accessible to see the bulges adding metal in the region of the head studs.
The block would split along a line approx at the bottom of the studs starting from those bulges and eventually extending bulge to bulge, simply cracking along a dotted line.
I guess engineering design was more years of experience whereas today a computer would do finite analysis and extra metal/thickening/finning would be added where necessary.
Looking at those heads brought back memories of crack repairs in that thin area around the injector.
Had many DC3 flights struggling with a 680 head in my hand luggage.
cav551:
I reckon you are correct, the AV 505, 691 and 760 dry liner engines all had a nitrided crankshaft like the Leyland. I recently had a Leyland 600 which had pulled one of the 3/8 head studs which needed a special stepped stud to be made in order to repair the block. The ‘big’ Leyland head is also noticeably heavier to lift off than the equivalent ‘big’ AEC one. I am about to tackle the problem of an AV590 which has sheared three studs in the block, two of which are already stepped. The bit about depth in the block reminds me that the 470 studs were buried quite some way down in the block, which also contributed to the overheating issue due to extension of the stud when warm.
Yes, probably the only benefit AEC gained from Leyland engine “know-how” was the introduction of nitrided crankshafts.
Harry Pick, a renowned AEC Service Engineer and later AEC / Leyland depot manager (Still alive at 90+) never used a torque wrench on a cylinder head. He always used a box spanner and tightened the nuts up by ‘feel’. He reckoned a box spanner and tommy bar gave equal strains and loading on the stud, wheras a torque wrench imposed unequal strains. If you think about it he is correct.
Dad never pulled a stud until he invested in the big torque wrench, makes one wonder that’s for sure.
Coming from an aircraft engine background, he said the ideal was to measure the bolt extension, rather than torque required to achieve that extension, too many variables involved with the torque method.
These days most studs are pulled down to moderate torque then finished off by the turn of the nut method using an angle indicator.
470 looks like they didn’t even try.
You got me scratching my head so I dug out the old 680 workshop manual.
Really obvious how poorly the studs are spaced on the engine’s left side.
Also the “bulges” in the block that I mentioned previously can be seen, there’s not much metal around the studs.
The whole top of the block would try to lift off along a crack line at the bottom of those bulges.
Cleaning the block surface while working in-situ can be a pain that’s for sure.
AEC never overcome the head gasket problem , so many failed that i know and mechanics could report yet another and get paid for some overtime sat in the pub , i still have some AEC head gaskets in my shed , the Leyland 400 and 370 could pull very heavy loads (20 ton) and never boil , the four -in-line had two axels and gave 11 ton combined when the single axel was 9 ton and total wid two axel tractor 20 ton , four in line was 24 ton as same as tandem bogie but three quarter ton lighter and all tyres conformed to road camber , so… equal loadings at all time ,tractor two axel 14 ton four in line 11 ton = 25 ton (leeway of 1 ton ) later single axel 10 ton and 24 total ,(even 32 ton wid three axel tractor possible) so no longer any need for four in line . DAF four in line the axels rotated ALL THE WAY so the punture was presented to the outside , easy and peasy .
Evening all, I’m trying to trace the history of an aec mercury which was driven by my father in the 70 s. It belonged to jack poulton and sons based in Hertfordshire and was a 4 wheeler cattle float Rev no bpx96 l. My father left in 79 and all I can remember is she was sold on in 81 or 82. If anyone could help I would be really grateful. There’s some great threads on here, particularly on the marathon, I loved them as a child and always wanted to do Iran for hrs.
Franky,
you might remember a few names that spring to mind from Tillotsons, Old Geordie Welsh the welder, old Albert cant recall his second name, seem to remember him specialising in fitting windscreens ( Hit it harder, GENTLY!) and the paint sprayer, was it Charlie? I swear he had the paint from every truck he ever painted ingrained in his hair and skin, Geordie Gill aka Geordie blob and Terry propshaft to name a few.
Happy days
Tim
Ah yes Tim, old George was a lovely bloke, he told me his Nephew was Alex Glasgow who did the title song of When The Boat Comes In, a popular Tyneside series at the time, learnt some stuff from him too. The two older Apprentices Bob Elliott and Granville Lee, what a pair they used to wind up Arthur (Art’y Laffer) the Manager, something terrible good laugh though. Dougie a nice quiet lad, a Blonde lad called Davy who went off to be a Traffic cop, Jack was a very good Fitter and nice bloke. The Foreman’s name escapes me at the moment, (ah just come back think it was Ian) but he was ok, I remember doing recovery work with him in the old Militant Wrecker, freezing in the winter though. We seemed to have a 50/50 mix of time served fitters and those lads that had done the 6 Month course a lot of Industries were doing at the time given the rather unflattering name of ‘Diluties’ but there were some nice lads amongst them. I enjoyed my time there and learnt some useful technical stuff, for a young lad it was a good place of work. Franky.
Frankydobo:
Ah yes Tim, old George was a lovely bloke, he told me his Nephew was Alex Glasgow who did the title song of When The Boat Comes In, a popular Tyneside series at the time, learnt some stuff from him too. The two older Apprentices Bob Elliott and Granville Lee, what a pair they used to wind up Arthur (Art’y Laffer) the Manager, something terrible good laugh though. Dougie a nice quiet lad, a Blonde lad called Davy who went off to be a Traffic cop, Jack was a very good Fitter and nice bloke. The Foreman’s name escapes me at the moment, (ah just come back think it was Ian) but he was ok, I remember doing recovery work with him in the old Militant Wrecker, freezing in the winter though. We seemed to have a 50/50 mix of time served fitters and those lads that had done the 6 Month course a lot of Industries were doing at the time given the rather unflattering name of ‘Diluties’ but there were some nice lads amongst them. I enjoyed my time there and learnt some useful technical stuff, for a young lad it was a good place of work. Franky.
Franky, was Ralph Scott at Tillotsons when you were there? He was at Waughs when I went there in 1972, he lived on Benton Rd, just a few yards from Tillotsons.
He was an artist with a big hammer and a bit of heat! Regards Kev.
Frankydobo:
Ah yes Tim, old George was a lovely bloke, he told me his Nephew was Alex Glasgow who did the title song of When The Boat Comes In, a popular Tyneside series at the time, learnt some stuff from him too. The two older Apprentices Bob Elliott and Granville Lee, what a pair they used to wind up Arthur (Art’y Laffer) the Manager, something terrible good laugh though. Dougie a nice quiet lad, a Blonde lad called Davy who went off to be a Traffic cop, Jack was a very good Fitter and nice bloke. The Foreman’s name escapes me at the moment, (ah just come back think it was Ian) but he was ok, I remember doing recovery work with him in the old Militant Wrecker, freezing in the winter though. We seemed to have a 50/50 mix of time served fitters and those lads that had done the 6 Month course a lot of Industries were doing at the time given the rather unflattering name of ‘Diluties’ but there were some nice lads amongst them. I enjoyed my time there and learnt some useful technical stuff, for a young lad it was a good place of work. Franky.
Franky, was Ralph Scott at Tillotsons when you were there? He was at Waughs when I went there in 1972, he lived on Benton Rd, just a few yards from Tillotsons.
He was an artist with a big hammer and a bit of heat! Regards Kev.
Franky, I’ve just been looking through the rest of the thread, you answered my question about Ralph Scott on page 1. Sorry!! regards. Kev.
gingerfold:
I’ve always had a high regard for the AEC Mercury both from a driver’s and operator’s viewpoint. The fixed cab GM4 series was in production from 1954 until 1965 and approximately 13,000 were produced. The Ergomatic tilt cab series TGM4 was in production from 1965 until 1977 and some 16,000 were built. In those years the 4-wheel rigid played an important role in general haulage as well as own account fleets, being used on long distance as well as local work. Arguably the Mercury was one of AEC’s finest lorries and set the benchmark for the premium class four-wheeler market. Export versions were badged as AEC Monarch.
Interesting that they used a synchromesh gearbox back then, I thought the later Ergomatic cabbed Marshall’s had a constant mesh one? Back in the sixties we used to service a Mustang owned by Gillette Industries, I assume they were similar mechanically to those in the brochures? I seem to remember it having the aircleaner in the cab though, and the little red ‘flags’ that popped up to let you know that you had now no brakes!
windrush:
Interesting that they used a synchromesh gearbox back then, I thought the later Ergomatic cabbed Marshall’s had a constant mesh one? Back in the sixties we used to service a Mustang owned by Gillette Industries, I assume they were similar mechanically to those in the brochures? I seem to remember it having the aircleaner in the cab though, and the little red ‘flags’ that popped up to let you know that you had now no brakes!
Pete.
Evening Pete
The 5-speed synchromesh 'box was replaced in 1962 /3 by the D196 5-speed direct drive constant mesh 'box, or more commonly the D197 6-speed overdrive constant mesh 'box. The synchro 'box was easy and delightful to use, it was as positive as a constant mesh box, you just had to be careful when changing gears, the gear lever positions for 2 and 4, and 3 and 5 were very close together. First gear was never needed except for a hill start loaded.
