Spun big end bearing - Rover V8
Discussion
Waiting for someone to explain the rod load doesn't double just the load increases with the square of the engine speed. I found an interesting report and analysis on a dead con rod.
After analysing the EDR data, which monitors the engine management system, it was observed that the engine failed suddenly, and lost power during braking and changing down gears into a corner. This is when the connecting rod experiences the highest tensile stress.
from
https://www.sciencedirect.com/science/article/pii/...
Peter
After analysing the EDR data, which monitors the engine management system, it was observed that the engine failed suddenly, and lost power during braking and changing down gears into a corner. This is when the connecting rod experiences the highest tensile stress.
from
https://www.sciencedirect.com/science/article/pii/...
Peter
PeterBurgess said:
Having slept on 'it', a question for folk who will be much more knowledgeable than me.
I'm listening. Please continue. 
PeterBurgess said:
Rods tend to fail after a long straight when folk put their foot down exiting the next corner.
No they don't. They tend to fail at the end of the straight on the overrun. During a very hot XR2 Challenge race at Castle Combe one August back in the mid 90s I watched 8 of the competitor's engines fail at exactly the same point at the end of the pit straight just as the drivers lifted off. Oil temps were reaching 130C becauses the class rules didn't allow coolers. Oil pressure at high rpm was dropping to 30 psi. The hydrodynamic lubrication wedge between the crank journal and bearing fails when the piston is at TDC and the full inertia of the piston and rod is acting on the underside of the big end journal. The bearing makes metal to metal contact, spins and the rod snaps. I've told this story before along with the engineering reason for such failures.https://www.pistonheads.com/gassing/topic.asp?h=0&...
PeterBurgess said:
Engineering tells us the load on the rods doubles when the throttle is closed as the power stroke cannot cushion the piston and rod and bearing anymore.
It is likely that the OP's bearing failed by this same mechanism when the operator lifted off the throttle after a power run with the thinner than desirable oil being used.You are only guessing at the reason for OP failure based on very little information, secondhand from dyno people and third hand from OP. A brief description and a pic.The bearings that have failed on me on the rollers have been under power and instant, the rattle says there is a problem. On the old rollers this was as soon as the pau took the full load at highish rpms and on the Dynocom in inertia mode when pms reached higher figures, none on over run.
I cannot agree with you saying failure of rod into corner, I think, from observation, if it is a rod failure (not just bearing) the rod fracture initiates on overun and propagates to failure as soon as load is applied after corner. Most pics, videos and eye witness shows the smoke comes out from under car after bend not before.
We had a prime example of this with two of our Bs running in a race on the continent, I think it was Spa. I was told there was a very long straight which meant feathering the throttle at max rpm on the straight followed by shut off at the end of the straight. In those days we were still running std rod bolts. I told both drivers to ease off at end of straight not sudden lift off. One driver was ok the other lifted off instantly as he had held on to pass a car right at the end of the straight. Result was rod bolt fail after the corner! Since then we have moved on to arp rod bolts or posher rods.
Peter
I cannot agree with you saying failure of rod into corner, I think, from observation, if it is a rod failure (not just bearing) the rod fracture initiates on overun and propagates to failure as soon as load is applied after corner. Most pics, videos and eye witness shows the smoke comes out from under car after bend not before.
We had a prime example of this with two of our Bs running in a race on the continent, I think it was Spa. I was told there was a very long straight which meant feathering the throttle at max rpm on the straight followed by shut off at the end of the straight. In those days we were still running std rod bolts. I told both drivers to ease off at end of straight not sudden lift off. One driver was ok the other lifted off instantly as he had held on to pass a car right at the end of the straight. Result was rod bolt fail after the corner! Since then we have moved on to arp rod bolts or posher rods.
Peter
I think we are being too polarised Dave( aren't we guilty of that a lot?) . Too many different types of bend, I am thinking of Mallory hairpin and coming out of the chicane onto the start finish straight of Donnington.
The report on the rod fail quote mentions losing power braking and changing down, surely this loss of power would show under +ve throttle not on over run? Maybe I am not reading the sentence properly.
Peter
The report on the rod fail quote mentions losing power braking and changing down, surely this loss of power would show under +ve throttle not on over run? Maybe I am not reading the sentence properly.
Peter
PeterBurgess said:
I cannot agree with you saying failure of rod into corner..
Well I watched 8 or 9 of them do it at exactly the same point BEFORE the cars got to the corner due to insufficient oil pressure. Maybe the drivers weren't fully aware of what had happened until they tried to re-apply power after the corner but all the spectators surely were. End of straight, brake lights come on, huge plume of smoke out of the exhaust, game over.These engines never fail under normal track conditions. This was an abnormally hot summer day compounded by the inability to run oil coolers which the organisers were lobbied about vigorously after this very event. It was a stupid rule which served no purpose. All drivers reported the same problem of 130C plus oil temps and consequent 30 psi or less pressure. Well, all except those with my engines as I built mine specifically to withstand such conditions. Very tight bearing clearances and a shim under the oil pressure relief valve spring. It was sufficient to mean no failures in the 10 or so engines I had in the field.
And yes you are not reading the article you linked to correctly. It is clear that this was also a failure on the overrun before the corner.
Really...too much speculation.
It seems we dont even know if the crank was good to start with, engine was properly cleaned during rebuild, rod journals good and rods themselves good, or indeed any details about the build other than these "trained" dyno operators were allowing an engine on their dyno with unsuitable oil in the engine and with no real monitor of oil pressure.
s
t has happened, throw the offending rod in the bin, thoroughly check all others prior to any rebuild, check crank, oil pump etc etc etc and put proper oil into it and keep a closer eye on things moving forward.
It seems we dont even know if the crank was good to start with, engine was properly cleaned during rebuild, rod journals good and rods themselves good, or indeed any details about the build other than these "trained" dyno operators were allowing an engine on their dyno with unsuitable oil in the engine and with no real monitor of oil pressure.
s
t has happened, throw the offending rod in the bin, thoroughly check all others prior to any rebuild, check crank, oil pump etc etc etc and put proper oil into it and keep a closer eye on things moving forward.Dave
Just back from Church where my good lady delivered a sermon, part of which was we have two ears to listen and only one mouth to talk rubbish, so maybe listen is important too. I will try if you will
I asked, of the forum, does the over run backed off destroy the bearing if there is a fault more rapidly than if the engine is brought down slowly. Dave,you seem to suggest it is the backing off at revs which destroyed the bearings I ask if this, in your opinion, would have not happened if the operator had not backed off but brought it down very steadily?
I think, if there had not been an inherent fault it would not have failed however it had been dynoed. This engine would probably have failed on the road or track I also think blaming the thin oil is a red herring. We have run dozens of race engines with straight 30 weight oil, no problems. We run Joe Gibbs break in oil which even states it is good for a dyno workout or a night's racing ( it doesn't say what will happen if you race in the daylight !).
If the picture had been presented without bringing dyno into the sights would people have said something different?
At the end of the day there is a knackered big end bearing, rod, and maybe crank journal. We do not know if the rod/s had been measured.
As a separate point, fitting arp bolts can ruin a big end if the bolt stretch requirement is greater than the capability of the rod. Seen this on a Cossie engine with std rods. The arp bolts were being changed for posher arp bolts requiring more stretch to achieve load. The stretch was achieved but relaxed after a while showing the rod was cowlapsing. Talking to Farndon this can be a common problem with supposed upgrades. Bits n pieces have to match.
Peter
Just back from Church where my good lady delivered a sermon, part of which was we have two ears to listen and only one mouth to talk rubbish, so maybe listen is important too. I will try if you will
I asked, of the forum, does the over run backed off destroy the bearing if there is a fault more rapidly than if the engine is brought down slowly. Dave,you seem to suggest it is the backing off at revs which destroyed the bearings I ask if this, in your opinion, would have not happened if the operator had not backed off but brought it down very steadily?
I think, if there had not been an inherent fault it would not have failed however it had been dynoed. This engine would probably have failed on the road or track I also think blaming the thin oil is a red herring. We have run dozens of race engines with straight 30 weight oil, no problems. We run Joe Gibbs break in oil which even states it is good for a dyno workout or a night's racing ( it doesn't say what will happen if you race in the daylight !).
If the picture had been presented without bringing dyno into the sights would people have said something different?
At the end of the day there is a knackered big end bearing, rod, and maybe crank journal. We do not know if the rod/s had been measured.
As a separate point, fitting arp bolts can ruin a big end if the bolt stretch requirement is greater than the capability of the rod. Seen this on a Cossie engine with std rods. The arp bolts were being changed for posher arp bolts requiring more stretch to achieve load. The stretch was achieved but relaxed after a while showing the rod was cowlapsing. Talking to Farndon this can be a common problem with supposed upgrades. Bits n pieces have to match.
Peter
PeterBurgess said:
Dave
Just back from Church where my good lady delivered a sermon, part of which was we have two ears to listen and only one mouth to talk rubbish, so maybe listen is important too.
It's probably best not to ever get me started on religion. The most evil and divisive force that has ever existed on this planet and the reason for more human suffering over the years than any other single cause. Believing in things for which there is zero evidence is delusional and IMO essentially a mental illness.Just back from Church where my good lady delivered a sermon, part of which was we have two ears to listen and only one mouth to talk rubbish, so maybe listen is important too.
What an enormous irony there is though in your wife standing at a pulpit pontificating on things which don't even exist and which she therefore cannot possibly have any knowledge of but telling everyone else it's better to listen than to speak. That's pretty much religion in a nutshell though. Do as we say not do as we do. I don't disagree with the general thrust of her advice of course other than that she probably needs to take it herself more than most other people. If all the preachers on this planet would learn to sit down and STFU the world would be a better place.
Even the most benign forms of religion such as perhaps C of E compared to say catholicism or islam have my condemnation too because the mindset that allows a person to believe in things that have no evidence allows them equally to not believe in things that do have evidence like global warming and evolution. That is why any form of religion is so dangerous. It is essentially the antithesis of the scientific method whereby facts and evidence are followed to their logical conclusion rather than the conclusion being formed first (by imaginary divine dictate perhaps) and the evidence then cherry picked to try and support it.
Following the facts and evidence is what allows us to build better engines, better computers, devise better medicine. Religion would cheerfully have us still stuck in the bronze age because every time science and religion butt heads religious dogma gets destroyed and goes away with its tail between its legs. Science loves new questions, new challenges, finding better answers to old theories. Religion loves saying "gawd says it's like this and so it will be forever after. If you disagree here's a stake and some kindling".
There's a lovely saying which sums it up nicely for me. "Science loves questions that can't be answered. Religion loves answers that can't be questioned".
Dave
1) A person can say there is a God or there is not a God but they will only find out when they die, not beforehand.
2) I would rather spend some time with a religious person who shows caring and love than a non religious bigot that attacks everything and everyone and tries to make me think like they do because they say so or shout loudly enough at me. Sandra would never tell someone how they should be, she teaches from the Bible and tries to live by good example. I have Hindu, Jewish, Christian, Bahai, Muslim and Sikh friends and acquaintances, none of whom has ever tried to tell me how to be! The Christian bible teaches you have choice/freewill and it is up to you how you use and live by choices and your freewill. I write about doctrine not about some humans who choose to use religion for further gain or power to the detriment of others.
3) You missed a bit in the link I gave you about the rod failure, I quote;
At the point of failure, the brake and throttle were being applied, increasing the magnitude of these forces.
Which implies the rod failed under load not on over run.
By the way, at no point does the analysis of the failure blame the driver for backing off!
Peter
1) A person can say there is a God or there is not a God but they will only find out when they die, not beforehand.
2) I would rather spend some time with a religious person who shows caring and love than a non religious bigot that attacks everything and everyone and tries to make me think like they do because they say so or shout loudly enough at me. Sandra would never tell someone how they should be, she teaches from the Bible and tries to live by good example. I have Hindu, Jewish, Christian, Bahai, Muslim and Sikh friends and acquaintances, none of whom has ever tried to tell me how to be! The Christian bible teaches you have choice/freewill and it is up to you how you use and live by choices and your freewill. I write about doctrine not about some humans who choose to use religion for further gain or power to the detriment of others.
3) You missed a bit in the link I gave you about the rod failure, I quote;
At the point of failure, the brake and throttle were being applied, increasing the magnitude of these forces.
Which implies the rod failed under load not on over run.
By the way, at no point does the analysis of the failure blame the driver for backing off!
Peter
Mignon said:
It's probably best not to ever get me started on religion. The most evil and divisive force that has ever existed on this planet and the reason for more human suffering over the years than any other single cause. Believing in things for which there is zero evidence is delusional and IMO essentially a mental illness.
What an enormous irony there is though in your wife standing at a pulpit pontificating on things which don't even exist and which she therefore cannot possibly have any knowledge of but telling everyone else it's better to listen than to speak. That's pretty much religion in a nutshell though. Do as we say not do as we do. I don't disagree with the general thrust of her advice of course other than that she probably needs to take it herself more than most other people. If all the preachers on this planet would learn to sit down and STFU the world would be a better place.
Even the most benign forms of religion such as perhaps C of E compared to say catholicism or islam have my condemnation too because the mindset that allows a person to believe in things that have no evidence allows them equally to not believe in things that do have evidence like global warming and evolution. That is why any form of religion is so dangerous. It is essentially the antithesis of the scientific method whereby facts and evidence are followed to their logical conclusion rather than the conclusion being formed first (by imaginary divine dictate perhaps) and the evidence then cherry picked to try and support it.
Following the facts and evidence is what allows us to build better engines, better computers, devise better medicine. Religion would cheerfully have us still stuck in the bronze age because every time science and religion butt heads religious dogma gets destroyed and goes away with its tail between its legs. Science loves new questions, new challenges, finding better answers to old theories. Religion loves saying "gawd says it's like this and so it will be forever after. If you disagree here's a stake and some kindling".
There's a lovely saying which sums it up nicely for me. "Science loves questions that can't be answered. Religion loves answers that can't be questioned".
There's so much in this post we need a "like" button for...What an enormous irony there is though in your wife standing at a pulpit pontificating on things which don't even exist and which she therefore cannot possibly have any knowledge of but telling everyone else it's better to listen than to speak. That's pretty much religion in a nutshell though. Do as we say not do as we do. I don't disagree with the general thrust of her advice of course other than that she probably needs to take it herself more than most other people. If all the preachers on this planet would learn to sit down and STFU the world would be a better place.
Even the most benign forms of religion such as perhaps C of E compared to say catholicism or islam have my condemnation too because the mindset that allows a person to believe in things that have no evidence allows them equally to not believe in things that do have evidence like global warming and evolution. That is why any form of religion is so dangerous. It is essentially the antithesis of the scientific method whereby facts and evidence are followed to their logical conclusion rather than the conclusion being formed first (by imaginary divine dictate perhaps) and the evidence then cherry picked to try and support it.
Following the facts and evidence is what allows us to build better engines, better computers, devise better medicine. Religion would cheerfully have us still stuck in the bronze age because every time science and religion butt heads religious dogma gets destroyed and goes away with its tail between its legs. Science loves new questions, new challenges, finding better answers to old theories. Religion loves saying "gawd says it's like this and so it will be forever after. If you disagree here's a stake and some kindling".
There's a lovely saying which sums it up nicely for me. "Science loves questions that can't be answered. Religion loves answers that can't be questioned".
Just don't start blaming God for your engine failures, although he must have been smiling down on this petrol engine today.
It drove fine, pulled well, quiet as a mouse, no odd noises, knocks etc, but when I changed the oil I checked the filter and found it stuffed with bearing material
Dropped the sump and found a few torn big end bearings, but no damage to the crank. Put some new shells in, rod bolts, two oil and filter changes (oil was so old the first change went black straight away) and she's good to go. Very very lucky as it's usually game over at this point.
It only holds 5 litres and change intervals are 12k ffs.
Just hope the rings aren't stuck as it's often the reason for the rapid rise in oil consumption....
For 10 bonus points what are those hanging out the bottom?
It drove fine, pulled well, quiet as a mouse, no odd noises, knocks etc, but when I changed the oil I checked the filter and found it stuffed with bearing material
Dropped the sump and found a few torn big end bearings, but no damage to the crank. Put some new shells in, rod bolts, two oil and filter changes (oil was so old the first change went black straight away) and she's good to go. Very very lucky as it's usually game over at this point.
It only holds 5 litres and change intervals are 12k ffs.
Just hope the rings aren't stuck as it's often the reason for the rapid rise in oil consumption....
For 10 bonus points what are those hanging out the bottom?
Edited by 227bhp on Tuesday 4th September 20:06
PeterBurgess said:
Dave
1) A person can say there is a God or there is not a God but they will only find out when they die, not beforehand.
One thing I'm very certain about is I'll be finding nothing new out after I'm dead because I'll be far too busy being dead. The best time for finding stuff out, like how facts, logic and the weight of evidence works, is while you're still alive. In the two or more millenia that people have been claiming the existence of a panoply of gods they've not managed to produce a single shred of evidence even one exists. There are a number of trite rebuttals the god botherers use to try and refute this such as you can't prove a negative and absence of evidence doesn't equal evidence of absence, neither of which are actually logically complete or true but the vast weight of evidence is that humans are somehow compelled to make up creation and deity stories and every such story is indeed fictional.1) A person can say there is a God or there is not a God but they will only find out when they die, not beforehand.
PeterBurgess said:
2) I would rather spend some time with a religious person who shows caring and love
I'd rather spend my own time with someone who is caring and loving and also rational and not living in a fantasy world.PeterBurgess said:
she teaches from the Bible
Oh really. Which bits? The bit where god is absolutely fine with slavery, i.e. keeping other people as property, and says it's ok to beat them with a rod as long as they don't die within 2 days? [Exodus 21:20]. If they survive to day 3 you're off the hook but even if not the punishment was suggested to be not very harsh because you'd already suffered enough by depriving yourself of valuable property.Maybe the various bits where god orders his true believers they have to kill anyone they meet who doesn't worship him including the entire population of a town if just one inhabitant there is not a believer, also gays, witches, children who curse their parents [Exodus 21:17], anyone who breaks the Sabbath [Exodus 31:12], anyone who doesn't listen to priests [Deuteronomy 17:12], adulterers [Leviticus 20:10], women who aren't virgins on their wedding night [Deuteronomy 22:20]?
Or perhaps like many Christians she is so unable to support the filth in the Old Testament (while probably being unwilling to admit that a supposedly infallible god had made such a mess of it) she tries to pretend it doesn't exist and just sticks to the touchy feely bits in the NT. Perhaps she needs to be aware that in the Sermon on the Mount Jesus said that while turning the other cheek might be all well and good he had not come to abolish any of the old Laws but to fulfil them and not one iota or dot will pass from the Law until all is accomplished. [Matthew 5:17].
So if you truly love the baby Jesus you'd better get out there and stab some gays for him quick sharp like. And no naughty opening your workshop on Saturday's either.
You see Peter I've actually studied all this stuff, in quite some depth, unlike most Christians who claim to have read the bible properly.
Something I find rather salutory is that if you tried to write the bible today as a new work you wouldn't be allowed to publish it in most countries because it would be classed as hate crime.
As to your questions about the bike engine article YOU linked to I suggest you contact the authors if you have any issues with it because I wasn't there.
And a good morning to you too Dave on this lovely, Sunny Autumn day, tis good to be alive.
Despite your bitterness a follower of nearly every faith, be it Islam, Buddha, Jesus, Hinduism would be there for you , who would you be willing to lay your life down for?
Sandra would be there for you even though you are angry towards her and have never even met her. True followers of any faith have a credo or a belief, they try to follow codes of being and looking after other people.
I am saddened you get so worked up by two ears to listen and one mouth to speak, that is not just from Christianity.
Do not judge your neighbour until you walk two moons in his moccasins. – Cheyenne
Lose your temper and you lose a friend; lie and you lose yourself. ~Hopi
When you were born, you cried and the world rejoiced. Live your life so that when you die, the world cries and you rejoice. – Cherokee
Listen, or your tongue will make you deaf
Peace and happiness are available in every moment. Peace is every step. We shall walk hand in hand. There are no political solutions to spiritual problems. Remember: If the Creator put it there, it is in the right place. The soul would have no rainbow if the eyes had no tears.
Personally I would rather see good in folk than evil, but deal with the evil should I have to.
A little thread drift but hopefully our engines will run fine and we will learn from our mistakes inshallah.
Peter
Despite your bitterness a follower of nearly every faith, be it Islam, Buddha, Jesus, Hinduism would be there for you , who would you be willing to lay your life down for?
Sandra would be there for you even though you are angry towards her and have never even met her. True followers of any faith have a credo or a belief, they try to follow codes of being and looking after other people.
I am saddened you get so worked up by two ears to listen and one mouth to speak, that is not just from Christianity.
Do not judge your neighbour until you walk two moons in his moccasins. – Cheyenne
Lose your temper and you lose a friend; lie and you lose yourself. ~Hopi
When you were born, you cried and the world rejoiced. Live your life so that when you die, the world cries and you rejoice. – Cherokee
Listen, or your tongue will make you deaf
Peace and happiness are available in every moment. Peace is every step. We shall walk hand in hand. There are no political solutions to spiritual problems. Remember: If the Creator put it there, it is in the right place. The soul would have no rainbow if the eyes had no tears.
Personally I would rather see good in folk than evil, but deal with the evil should I have to.
A little thread drift but hopefully our engines will run fine and we will learn from our mistakes inshallah.
Peter
I'm well aware Peter that the first thing theists try to fling at atheists is that they're bitter and angry. It's a deflection of sorts I'll warrant but then deflection is about all they really have to fall back on. I'm not sure how we are meant to be bitter and angry at something that doesn't exist anymore than we would be bitter and angry at unicorns or leprachauns. It's easier having evidence to fall back on, or in atheist's case the complete lack of it from the other side.
Oh who am I kidding? lol. I f**king hate unicorns. They're just horsies with horns and a huge superiority complex
Oh who am I kidding? lol. I f**king hate unicorns. They're just horsies with horns and a huge superiority complex
I am an atheist Dave, I respect the rights of theists and admire the way most try and be good people, I am trying to be a better person because I want to be. I still think it is a shame you get so angry about what, if it doesn't exist, does not matter one jot. Be careful, look at Saul's hatred before he turned into Paul
Sunshine has gone and the sky is rather grey now. The Leprechauns and Unicorns have gone for the day.
Peter
Sunshine has gone and the sky is rather grey now. The Leprechauns and Unicorns have gone for the day.
Peter
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