railstaff:
If it had wings I think at this point this thread would take off,some well respected(by myself) views coming through now.
Taking the wet V dry liner debate.I think for the gains in cooling and with a proper counter bore and fire ring set up and I’m thinking 855 counter bore and Volvo TD122 fire ring locating in to the cylinder head,it out ways the problems of electrolysis and cavition.Which a lot of this fault was rectified with a decent earthing ■■■■■■■■ the block to eliminate static.Without doubt 855 suffered enormously with rotton liners,with an average life span of 7 years.
Do you think the engine could have been changed to a wet liner design? Looking at the phots of the sectioned engine, there is plenty of room to put a much thicker liner, which would be (potentially) stiffer than the liner/block double-thickness arrangement as it was.
Why are wet liners more prone to cavitation? To my knowledge, this occurs in areas of steep pressure gradients- the evaporation occurs at the lower pressure position then, when the bubbles travel to a higher pressure area, the shock wave caused by their collapse is sufficient to induce fatigue damage into any adjacent surface. I have observed erosion similar to that on ball bearing races. I would have thought that the larger area of the cooling jacket, at least on the AEC engine, would have reduced the flow speed in that area and, with that, the possibility of turbulence.
Electrolysis was a problem cured by the use of inhibitors. Gardners and many other engines used aluminium and iron in contact with the same electrolyte.
cav551:
While that is what one would think my oil supplier argues differently. I am aware that they wish to sell their speciality product however I go along with what they say…if only i could remember it correctly!!
According to *** oils modern oils are designed for the much closer working tolerances and greater running temperatures of modern engines. This does not necessarily suit older designed engines and particularly ones which do not have similar efficient filtration to today’s vehicles or even any filtration at all. IIRC the argument then goes that the detergent additives in modern oils carry dirt in suspension which is not removed efficiently by the filters fitted. The oil and the additives also does not work well with the greater clearance between piston and bore resulting in bore glazing and /or varnish deposits gumming up piston rings.
Speaking specifically about the AEC V8, the general consensus is that modern semi synthetic oils will help the engine in many more ways than they will affect it in a negative way.
It has good filtration, and as long as we use these modern oils in the ‘as new’ engine from the offset, there should be no build up of carbon to become loosened inside that can cause problems when switching to high detergent oils after prolonged service with lower grade lubricants.
Just for interest, these are the clearances for a new AEC V8 AV740 engine, and they were strictly observed when my engine 316 was built. Any components that didn’t make the grade were discarded, however challenging that was!.
Crankshaft journals (mains) 0.0054” to 0.0028” Crankshaft (big ends) 0.0048” to 0.0027” Crankshaft end float 0.017” to 0.011” Cylinder liner to extreme piston top 0.0396” to 0.0356” Cylinder liner to bottom of piston skirt 0.0117” to 0.0097” Piston ring gaps 0.027” to 0.020” Gudgeon pin to small end bearing 0.0027” to 0.0017”
gingerfold:
ERF, as Keith Roberts was also responsible for development of the TL12 engine are you aware of any of the lessons learnt from the V8 being incorporated into the TL12? Incidentally I have just discovered that 25 Marathon TL12s were exported to Bolivia and operated successfully at altitudes above 15,000 feet in the Andes.
The only V8 lessons that I know that were definitely incorporated into the TL12 were related to the crankshaft hardening and the associated bearings, but it is inconceivable that there were not many other lessons transferred from the V8 project.
You mention operation at altitude, and I have documentation recording that AEC did extensive testing with the V8 in these conditions, and without doubt the information gathered would have benefited the TL12 project.
railstaff:
If it had wings I think at this point this thread would take off,some well respected(by myself) views coming through now.
Taking the wet V dry liner debate.I think for the gains in cooling and with a proper counter bore and fire ring set up and I’m thinking 855 counter bore and Volvo TD122 fire ring locating in to the cylinder head,it out ways the problems of electrolysis and cavition.Which a lot of this fault was rectified with a decent earthing ■■■■■■■■ the block to eliminate static.Without doubt 855 suffered enormously with rotton liners,with an average life span of 7 years.
Do you think the engine could have been changed to a wet liner design? Looking at the phots of the sectioned engine, there is plenty of room to put a much thicker liner, which would be (potentially) stiffer than the liner/block double-thickness arrangement as it was.
Why are wet liners more prone to cavitation? To my knowledge, this occurs in areas of steep pressure gradients- the evaporation occurs at the lower pressure position then, when the bubbles travel to a higher pressure area, the shock wave caused by their collapse is sufficient to induce fatigue damage into any adjacent surface. I have observed erosion similar to that on ball bearing races. I would have thought that the larger area of the cooling jacket, at least on the AEC engine, would have reduced the flow speed in that area and, with that, the possibility of turbulence.
Electrolysis was a problem cured by the use of inhibitors. Gardners and many other engines used aluminium and iron in contact with the same electrolyte.
Anything could be done if redesigning the block isn’t an issue.Seems strange but true that the use of parent bore was to stiffen the block when they choose to fit single piece heads.This we now question only after another 50 years of development.
Not all wet liners are prone to cavitation,some engines never suffer,855/N14/M11 are just bad for it.
cav551:
While that is what one would think my oil supplier argues differently. I am aware that they wish to sell their speciality product however I go along with what they say…if only i could remember it correctly!!
According to *** oils modern oils are designed for the much closer working tolerances and greater running temperatures of modern engines. This does not necessarily suit older designed engines and particularly ones which do not have similar efficient filtration to today’s vehicles or even any filtration at all. IIRC the argument then goes that the detergent additives in modern oils carry dirt in suspension which is not removed efficiently by the filters fitted. The oil and the additives also does not work well with the greater clearance between piston and bore resulting in bore glazing and /or varnish deposits gumming up piston rings.
Speaking specifically about the AEC V8, the general consensus is that modern semi synthetic oils will help the engine in many more ways than they will affect it in a negative way.
It has good filtration, and as long as we use these modern oils in the ‘as new’ engine from the offset, there should be no build up of carbon to become loosened inside that can cause problems when switching to high detergent oils after prolonged service with lower grade lubricants.
Just for interest, these are the clearances for a new AEC V8 AV740 engine, and they were strictly observed when my engine 316 was built. Any components that didn’t make the grade were discarded, however challenging that was!.
Crankshaft journals (mains) 0.0054” to 0.0028” Crankshaft (big ends) 0.0048” to 0.0027” Crankshaft end float 0.017” to 0.011” Cylinder liner to extreme piston top 0.0396” to 0.0356” Cylinder liner to bottom of piston skirt 0.0117” to 0.0097” Piston ring gaps 0.027” to 0.020” Gudgeon pin to small end bearing 0.0027” to 0.0017”
Quite a lot of piston clearance at the skirt,maybe designed in for reasons I highlighted.Perhaps in service piston damage was done by not allowing them to warm up properly.
Maybe AEC had the same problem as ■■■■■■■ had with the small cams.Too much oil pressure and too high viscosity on cold engines which resulted in being unkind on bearing faces.
Well done for getting to this stage with the build.
newmercman:
I never had a single electrical problem on any of the IVECO I’ve owned, although things have changed since 05 when I bought the last one I had.
Sent from my SM-G950W using Tapatalk
We had quite a few Ivecos on 53 to 05 plates and they were for ever going backwards and forwards to the main dealer with abs/ebs faults which were never solved .They were replaced by CF Dafs when their leases were up. I was talking to an operator a couple of days ago and he runs 10 new Ivecos and he said nothings changed they are just as bad
ramone:
As I`ve mentioned before I know nothing about engines but would intercooling have helped the V8 if it had been available at the time?
It wouldn’t have helped it’s reliability, but would have increased it’s potential power output in turbocharged form.
Cold air is denser than hot air, and therefore contains more oxygen.
The pressurised air that leaves an engine’s turbocharger compressor is very hot, so to get more oxygen into the cylinder, and therefore a bigger bang from the fuel injected, the air needs to be cooled down as much as possible after it leaves the turbocharger and before it arrives at the cylinder.
The pressurised air is passed through either an intercooler (a radiator for the air, usually made of aluminium and mounted in front of the engine cooling radiator), or an aftercooler (a heat exchanger that cools the air using engine coolant), or in some cases both are used together.
newmercman:
I must have been lucky then. As I’m sure some were with V8 Mandators, there must have been a few that were reliable?
Sent from my SM-G950W using Tapatalk
Well we had Tec cab and Turbostars in the late `80s and the engines were bullet proof but the cabs fell apart , having said that they were never serviced on a regular basis and were on route to either Italy or Germany every week … and 2 Renaults were added a 340 and a 365 which were suprisingly good on Italy
ramone:
As I`ve mentioned before I know nothing about engines but would intercooling have helped the V8 if it had been available at the time?
It wouldn’t have helped it’s reliability, but would have increased it’s potential power output in turbocharged form.
Cold air is denser than hot air, and therefore contains more oxygen.
The pressurised air that leaves an engine’s turbocharger compressor is very hot, so to get more oxygen into the cylinder, and therefore a bigger bang from the fuel injected, the air needs to be cooled down as much as possible after it leaves the turbocharger and before it arrives at the cylinder.
The pressurised air is passed through either an intercooler (a radiator for the air, usually made of aluminium and mounted in front of the engine cooling radiator), or an aftercooler (a heat exchanger that cools the air using engine coolant), or in some case both are used together.
There you go i know nothing and prove it … thanks for the reply though
ramone:
As I`ve mentioned before I know nothing about engines but would intercooling have helped the V8 if it had been available at the time?
It wouldn’t have helped it’s reliability, but would have increased it’s potential power output in turbocharged form.
Cold air is denser than hot air, and therefore contains more oxygen.
The pressurised air that leaves an engine’s turbocharger compressor is very hot, so to get more oxygen into the cylinder, and therefore a bigger bang from the fuel injected, the air needs to be cooled down as much as possible after it leaves the turbocharger and before it arrives at the cylinder.
The pressurised air is passed through either an intercooler (a radiator for the air, usually made of aluminium and mounted in front of the engine cooling radiator), or an aftercooler (a heat exchanger that cools the air using engine coolant), or in some cases both are used together.
There you go i know nothing and prove it … thanks for the reply though
Well, I still learn something new most days!.
As we say around here…’everyday is a school day’!
Renault are a different story, I had a Magnum that was plagued with electrical problems, that thing was possessed, the lights, indicators or wipers would randomly go on or off, on when it was parked in the yard and off when you were driving in the rain at night. A real shame as it was such a nice lorry in every other way, it drove me up the wall because as with most intermittent electrical faults, nobody could find the problem.
railstaff:
If it had wings I think at this point this thread would take off,some well respected(by myself) views coming through now.
Taking the wet V dry liner debate.I think for the gains in cooling and with a proper counter bore and fire ring set up and I’m thinking 855 counter bore and Volvo TD122 fire ring locating in to the cylinder head,it out ways the problems of electrolysis and cavition.Which a lot of this fault was rectified with a decent earthing ■■■■■■■■ the block to eliminate static.Without doubt 855 suffered enormously with rotton liners,with an average life span of 7 years.
Do you think the engine could have been changed to a wet liner design? Looking at the phots of the sectioned engine, there is plenty of room to put a much thicker liner, which would be (potentially) stiffer than the liner/block double-thickness arrangement as it was.
Why are wet liners more prone to cavitation? To my knowledge, this occurs in areas of steep pressure gradients- the evaporation occurs at the lower pressure position then, when the bubbles travel to a higher pressure area, the shock wave caused by their collapse is sufficient to induce fatigue damage into any adjacent surface. I have observed erosion similar to that on ball bearing races. I would have thought that the larger area of the cooling jacket, at least on the AEC engine, would have reduced the flow speed in that area and, with that, the possibility of turbulence.
Electrolysis was a problem cured by the use of inhibitors. Gardners and many other engines used aluminium and iron in contact with the same electrolyte.
Anything could be done if redesigning the block isn’t an issue.Seems strange but true that the use of parent bore was to stiffen the block when they choose to fit single piece heads.This we now question only after another 50 years of development.
Not all wet liners are prone to cavitation,some engines never suffer,855/N14/M11 are just bad for it.
Increasing the bore of the casting to “lose” the cylinder wall would be a cheap tooling change, I would have thought. It is a bit more than a detail change but, if Mr. ERF is demanding 450bhp for his 1982 model Mandators, it is a change worth pursuing over the next decade .
Do ■■■■■■■ engines have a bigger-than-usual pressure drop across the water pump? That would be a pointer to the cavitation issue, and it would be apparent in the power consumption of the pump.
Good question,simple answer I don’t know.I gather it depends on how fast the water can enter the inlet of the pump.One thing with a ■■■■■■■ liner is its only cooled half way down its lenth,855 is a considerable bit more.
One problem I can see with machining the parent bore away is the deck would become detatched,wet liner blocks still have an internal wall between the cylinders,a bit like a box.To achieve this a longer block would be needed as by the looks of it the new counter bore would be very close to the block studs,but still a good idea with merit.
railstaff:
Good question,simple answer I don’t know.I gather it depends on how fast the water can enter the inlet of the pump.One thing with a ■■■■■■■ liner is its only cooled half way down its lenth,855 is a considerable bit more.
One problem I can see with machining the parent bore away is the deck would become detatched,wet liner blocks still have an internal wall between the cylinders,a bit like a box.To achieve this a longer block would be needed as by the looks of it the new counter bore would be very close to the block studs,but still a good idea with merit.
I can see that being a problem. At least some of the head/block stud holes in the wet liner 690 engine break through into the water jacket. This obviously causes problems with corrosion to the threads and studs shearing. Unlike the 760 and V8 the wet liner engines have 1/2" head studs. It is very common to find that the block has been drilled and tapped for an oversize stepped stud. On the engines I see either there has been considerable damage or since they have been overhauled several times in their lives, it is common to find that the block has been re threaded 5/8" where necessary. Since the V8 starts off at 9/16" to allow for block recovery there would need to be sufficient material to retap to 3/4". However IIRC the TL12 engine block was tapped 5/8" ex factory.
… thanks for the reply though
