Big end bearings
Discussion
The most likely issue for shell bearing wear is how the engine has been used; ultimately how many high RPM thrashings.
As revs increase the inertia loading on the bearings and rod bolts is HUGE...(quoted from another source to save typing)
For example, at 6,000 rev/min the loading is four times that at 3,000. It is not difficult, in view of the foregoing, to see why big-end failure may occur if the revs are pushed even just a little higher than normal, if at the " normal " point, the bearing construction is loaded fairly well to its safe limit. Thus, an engine that travels happily for mile after mile at 4,500 rev/min should not necessarily be condemned if bearing failure happens after a brisk bout at 5,000. The extra 500 revolutions has increased the big-end bearing loading by nearly 25 per cent.
The S65 engine revs very high for a V8, and naturally given it's lack of low down torque and delightful noise higher up the rev range, people naturally rev the life out of them.
If I were replacing the shells, a must is to upgrade the bolts too as these stretch with age and temperature.
As revs increase the inertia loading on the bearings and rod bolts is HUGE...(quoted from another source to save typing)
For example, at 6,000 rev/min the loading is four times that at 3,000. It is not difficult, in view of the foregoing, to see why big-end failure may occur if the revs are pushed even just a little higher than normal, if at the " normal " point, the bearing construction is loaded fairly well to its safe limit. Thus, an engine that travels happily for mile after mile at 4,500 rev/min should not necessarily be condemned if bearing failure happens after a brisk bout at 5,000. The extra 500 revolutions has increased the big-end bearing loading by nearly 25 per cent.
The S65 engine revs very high for a V8, and naturally given it's lack of low down torque and delightful noise higher up the rev range, people naturally rev the life out of them.
If I were replacing the shells, a must is to upgrade the bolts too as these stretch with age and temperature.
.Mikeeb said:
S65's suffer from the same problem too.
But not at anything near the same level.One USA guy alone on M5board has sold 280 replacement S85 engines for a total production run of some 20500 S85 V10s.
The whole of M3post has recorded a total of ~100 engine failures for a total production run of 65,000 S65 V8s.
Pro rata that makes the S85 some 9 times more likely to fail than an S65 M3.
Both engines had the same bearings and clearances.
S65 engine was in production from 2007-2013 (8400rpm red line), S85 from 2005-2010 (8250rpm red line). It's difficult to compare like with like failures at this stage, maybe in two years we will see more S85 issues - but hopefully not.
Regardless, I'll be getting the M6 looked at soon since it's done 82k miles. In response to warm up temperatures, can something be done like the M3 CSL warm up lights?
From P0lar on m3forum.net
"Part of the rationale to make these changes is that the default behaviour for the non-CSL E46 M3 is to have the last positional threshold set to 60°C; in other words, the last light goes out at 60°C. Actual operating temperature of the engine, in terms of the oil at least, is closer to 82-83°C. Many people feel that by the time the last light is out, the car is ready to redline. While it may not be dangerous to the engine's internals, these engines are known for sensitive rod bearings. Taxing the engine at redline some 20°C+ below actual operating temperature simply cannot be in its best interest.
This modification alerts the driver that the engine has reached a higher pre-set determination for the oil temperature by extinguishing the last light later in the warm-up cycle. The CSL was configured to extinguish the last light at 80°C, which is very near to actual engine-operating temperature."
Regardless, I'll be getting the M6 looked at soon since it's done 82k miles. In response to warm up temperatures, can something be done like the M3 CSL warm up lights?
From P0lar on m3forum.net
"Part of the rationale to make these changes is that the default behaviour for the non-CSL E46 M3 is to have the last positional threshold set to 60°C; in other words, the last light goes out at 60°C. Actual operating temperature of the engine, in terms of the oil at least, is closer to 82-83°C. Many people feel that by the time the last light is out, the car is ready to redline. While it may not be dangerous to the engine's internals, these engines are known for sensitive rod bearings. Taxing the engine at redline some 20°C+ below actual operating temperature simply cannot be in its best interest.
This modification alerts the driver that the engine has reached a higher pre-set determination for the oil temperature by extinguishing the last light later in the warm-up cycle. The CSL was configured to extinguish the last light at 80°C, which is very near to actual engine-operating temperature."
crankedup said:
1k seems to be good value. I have to ask, purely as I am trying to learn and understand the e46 M engine, Is your engine showing any signs of wear? Do the bearings just suddenly go pop, this all seems just so alien to what I have known over the past 50 years of motorbikes and car engines.
No signs of any issues, just want it doing "just incase". Trouble is as soon as a sign is there it's usually too late so I'd rather spend £1k now than £4-5k later.Steve
Gouki said:
S65 engine was in production from 2007-2013 (8400rpm red line), S85 from 2005-2010 (8250rpm red line). It's difficult to compare like with like failures at this stage,
But thats 280 replacement engines from *one guy* making the V10 S85 ~9 times more unreliable. Imagine how many hundreds of V10 S85 engines BMW replaced under warranty and extended warranty over the same time period.
A couple of years difference in production is never going to make up that difference.
Logically, looking at what BMW changed and what they didn't change when they derived the S65 M3 from the S85 V10 will indicate what is and isn't the cause of the dramatic improvement in reliability of the S65 M3.
Steve Barrett said:
crankedup said:
1k seems to be good value. I have to ask, purely as I am trying to learn and understand the e46 M engine, Is your engine showing any signs of wear? Do the bearings just suddenly go pop, this all seems just so alien to what I have known over the past 50 years of motorbikes and car engines.
No signs of any issues, just want it doing "just incase". Trouble is as soon as a sign is there it's usually too late so I'd rather spend £1k now than £4-5k later.Steve
Max Maxasson said:
But thats 280 replacement engines from *one guy* making the V10 S85 ~9 times more unreliable.
Imagine how many hundreds of V10 S85 engines BMW replaced under warranty and extended warranty over the same time period.
A couple of years difference in production is never going to make up that difference.
Logically, looking at what BMW changed and what they didn't change when they derived the S65 M3 from the S85 V10 will indicate what is and isn't the cause of the dramatic improvement in reliability of the S65 M3.
What do you believe the mods were that have made the difference?Imagine how many hundreds of V10 S85 engines BMW replaced under warranty and extended warranty over the same time period.
A couple of years difference in production is never going to make up that difference.
Logically, looking at what BMW changed and what they didn't change when they derived the S65 M3 from the S85 V10 will indicate what is and isn't the cause of the dramatic improvement in reliability of the S65 M3.
From Wikipedia
'The S65 shares the same 92 mm (3.6 in) bore and 75.2 mm (3.0 in) stroke cylinder dimensions with the S85 V10, along with the Double-VANOS variable valve timing system and 12.0:1 compression ratio.
A wet-sump lubrication system with an oil return pump and a main oil pump replaces the three-pump wet-sump system used on the V10, further decreasing weight.[3][4] The alternator disconnects from the engine during acceleration to maximise power, only charging the battery during braking and decelerating whenever possible, in a system BMW calls Brake Energy Regeneration.'
Again, I'm a far cry from an engineer, but look at analytical data every day. Due to the anecdotal evidence presented and without a firm engineering reason to point to the failure rates are higher on either engine - you've got to agree that it's hard to state it as fact?
I have no bias either way in this.
'The S65 shares the same 92 mm (3.6 in) bore and 75.2 mm (3.0 in) stroke cylinder dimensions with the S85 V10, along with the Double-VANOS variable valve timing system and 12.0:1 compression ratio.
A wet-sump lubrication system with an oil return pump and a main oil pump replaces the three-pump wet-sump system used on the V10, further decreasing weight.[3][4] The alternator disconnects from the engine during acceleration to maximise power, only charging the battery during braking and decelerating whenever possible, in a system BMW calls Brake Energy Regeneration.'
Again, I'm a far cry from an engineer, but look at analytical data every day. Due to the anecdotal evidence presented and without a firm engineering reason to point to the failure rates are higher on either engine - you've got to agree that it's hard to state it as fact?
I have no bias either way in this.
As noted above plus a more powerful ECU and a rework of the ion sensing anti knock system.
If you are BMW and commit to spending a decent amount of money on modifying the S85 to produce the S65...where do you spend the money (apart from on the architecture) if not on increasing reliability?
If you see massively improved reliability, is it not far to conclude that your changes were successful?
If you are BMW and commit to spending a decent amount of money on modifying the S85 to produce the S65...where do you spend the money (apart from on the architecture) if not on increasing reliability?
If you see massively improved reliability, is it not far to conclude that your changes were successful?
Max Maxasson said:
As noted above plus a more powerful ECU and a rework of the ion sensing anti knock system.
If you are BMW and commit to spending a decent amount of money on modifying the S85 to produce the S65...where do you spend the money (apart from on the architecture) if not on increasing reliability?
If you see massively improved reliability, is it not far to conclude that your changes were successful?
A few terms like above are not facts, we don't know how much R&D spend was spent on each engine. 'You see massively improved reliability' is again not proven and anecdotal. When did BMW start seeing engine failures for the V10, how would these failures factor into the research and design cycle for the V8? Unless the failures appeared during the first year or so, BMW would have performed a recall a la the E46.If you are BMW and commit to spending a decent amount of money on modifying the S85 to produce the S65...where do you spend the money (apart from on the architecture) if not on increasing reliability?
If you see massively improved reliability, is it not far to conclude that your changes were successful?
The same American engine builder could be fixing/replacing more V8s in the coming years over V10s, or vice versa or less because more and more people replace their shells. Who is the American engine replacer, can you provide a link?
Also you've stated in the past that these issues are only observed in the USA for the E92 M3? You've ignored US data before but are happy to include it now.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
I think you are likely a little bit E92 biased.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
I think you are likely a little bit E92 biased.
Patrick Bateman said:
I always ignored the lights and just kept it below 3000rpm until the oil was getting close to operating temperature.
Agreed - on both my M5 and Z4M I keep the load and revs as low as reasonably possible until the oil is up to temp, taking a longer/slower route if needed. Once the oil is up to temp I try to keep the cobwebs off the 8000 rpm portion of the tach from time to time but I never ever use the lower "redlines" indicated by the Z4M's tach lights or the rising scale on the M5 - seems like it would be bloody daft that 6000 rpm is OK in a cold engine when 8000 isn't.Gouki said:
Who is the American engine replacer, can you provide a link?
Troy Jeup on M5board.Gouki said:
Also you've stated in the past that these issues are only observed in the USA for the E92 M3? You've ignored US data before but are happy to include it now.
What are you on about?One of the trends is indeed that USA S65s are less reliable than UK S65s.
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