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E60 M5 and E61 M5 Touring Discussion 2005- Advertiser's Forum

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post #51 of 58 Old 8th April 2019, 04:00 PM Thread Starter
gpeterson
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Originally Posted by Alan Arnesen View Post
How many miles are on those?
104k

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Assuming the ones with more wear are the uppers?
Correct
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post #52 of 58 Old 9th April 2019, 12:11 AM
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Originally Posted by Alan Arnesen View Post
How many miles are on those? Assuming the ones with more wear are the uppers? I've had my car for about three weeks and the bearings done about 10k ago. Trying to prepare for the future.

The oil viscosity discussion is interesting. I have been working on cars since I was old enough to walk. I have been sailing on ships as an engineer for almost 30 years. The rotation of the crank and friction wedge prevent the crank from touching the bearing. A lower viscosity oil would flow more at a given pressure and provide more cooling. Based on my knowledge start up is when 90% of bearing wear takes place. I plan on installing an accumulator to reduce bearing wear.

The other part of the equation is RPM/Mile. If you are revving an engine to 7k and doing 50mph you have 350,000rev/mile. If you are cruising at 2000rpm you have 100,000rev/mile. As you can see the actual number of rotations the engine makes per our standard unit of measurement is higher. I think for what they are the engine do pretty darn well considering what we are getting out of them
Curious how would you install the accumalotor?
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post #53 of 58 Old 9th April 2019, 12:22 AM
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Quote:
Originally Posted by Alan Arnesen View Post
How many miles are on those? Assuming the ones with more wear are the uppers? I've had my car for about three weeks and the bearings done about 10k ago. Trying to prepare for the future.

The oil viscosity discussion is interesting. I have been working on cars since I was old enough to walk. I have been sailing on ships as an engineer for almost 30 years. The rotation of the crank and friction wedge prevent the crank from touching the bearing. A lower viscosity oil would flow more at a given pressure and provide more cooling. Based on my knowledge start up is when 90% of bearing wear takes place. I plan on installing an accumulator to reduce bearing wear.

The other part of the equation is RPM/Mile. If you are revving an engine to 7k and doing 50mph you have 350,000rev/mile. If you are cruising at 2000rpm you have 100,000rev/mile. As you can see the actual number of rotations the engine makes per our standard unit of measurement is higher. I think for what they are the engine do pretty darn well considering what we are getting out of them
I thought rpm stands for revolutions per minute. So if you're going 7k, and you're going 50mph, roughly little under a mile per minute why would your engine spin more than 7k? Even if you are considering each bearing as stand alone, that'd still be 7000 x 10? 70,000?

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post #54 of 58 Old 9th April 2019, 12:29 AM
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Originally Posted by Alan Arnesen View Post
How many miles are on those? Assuming the ones with more wear are the uppers? I've had my car for about three weeks and the bearings done about 10k ago. Trying to prepare for the future.

The oil viscosity discussion is interesting. I have been working on cars since I was old enough to walk. I have been sailing on ships as an engineer for almost 30 years. The rotation of the crank and friction wedge prevent the crank from touching the bearing. A lower viscosity oil would flow more at a given pressure and provide more cooling. Based on my knowledge start up is when 90% of bearing wear takes place. I plan on installing an accumulator to reduce bearing wear.

The other part of the equation is RPM/Mile. If you are revving an engine to 7k and doing 50mph you have 350,000rev/mile. If you are cruising at 2000rpm you have 100,000rev/mile. As you can see the actual number of rotations the engine makes per our standard unit of measurement is higher. I think for what they are the engine do pretty darn well considering what we are getting out of them
I've been down the thinner oil route and after 14k miles pulled the OEM clearance bearings. Zero improvement, same pattern of wear indicating starvation. I've now had 7 engines apart with larger (more correct) oil clearance bearings and while wear occurs on any plain bearing, the degree is far, far less and the pattern more uniform, indicative of proper lubrication. On these engines, the wear occurs at high RPM as the film depletion rate is greater than the supply rate and the thickness of the oil wedge insufficient. Increasing the oil clearance and staying with the 10W-60 (oddly, per Clevite's recommendation) yields a properly running and wearing motor.
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post #55 of 58 Old 9th April 2019, 01:05 AM
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I've been down the thinner oil route and after 14k miles pulled the OEM clearance bearings. Zero improvement, same pattern of wear indicating starvation. I've now had 7 engines apart with larger (more correct) oil clearance bearings and while wear occurs on any plain bearing, the degree is far, far less and the pattern more uniform, indicative of proper lubrication. On these engines, the wear occurs at high RPM as the film depletion rate is greater than the supply rate and the thickness of the oil wedge insufficient. Increasing the oil clearance and staying with the 10W-60 (oddly, per Clevite's recommendation) yields a properly running and wearing motor.

Very good info. Thanks Jim.

In your opinion, the variability we are seeing in bearing wear from car to car, do you think this is down to user treatment, or variations in the bearing clearance?
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post #56 of 58 Old 9th April 2019, 01:38 AM
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For 104k miles they don't really look that bad. My bearings were done 10k ago by the PO. Whatever is in there i'm stuck with for now. I agree with you assessment about clearance and starvation. For me the only things I can change is the oil and add an accumulator. There is a thread on the forum, not like it was my idea. Not sure it will solve the problem but I am sure it won't hurt. Somewhere after the oil filter with a solenoid activated by the start command for the engine.
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post #57 of 58 Old 9th April 2019, 03:39 AM
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Very good info. Thanks Jim.

In your opinion, the variability we are seeing in bearing wear from car to car, do you think this is down to user treatment, or variations in the bearing clearance?
I'm not Jim but yes, in my opinion engine to engine variation means you could have a larger clearance engine and experience less wear. Explains the odd one that shows up from time to time showing little wear.

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I've been down the thinner oil route and after 14k miles pulled the OEM clearance bearings. Zero improvement, same pattern of wear indicating starvation. I've now had 7 engines apart with larger (more correct) oil clearance bearings and while wear occurs on any plain bearing, the degree is far, far less and the pattern more uniform, indicative of proper lubrication. On these engines, the wear occurs at high RPM as the film depletion rate is greater than the supply rate and the thickness of the oil wedge insufficient. Increasing the oil clearance and staying with the 10W-60 (oddly, per Clevite's recommendation) yields a properly running and wearing motor.
Evidence like this should be in a sticky. Even then people will still claim the issue is due to too thick oil...

Last edited by flacoramos; 9th April 2019 at 03:40 AM.
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post #58 of 58 Old 9th April 2019, 06:11 AM
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I'm not Jim but yes, in my opinion engine to engine variation means you could have a larger clearance engine and experience less wear. Explains the odd one that shows up from time to time showing little wear.



Evidence like this should be in a sticky. Even then people will still claim the issue is due to too thick oil...


Exactly it’s not all about thick oil.


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