Another Bearing thread

[Doc Oc]

Originally Posted by swamp2

One can make some pretty reasonable estimates/calculations to get around this significant limitation of the data.

The range of total failure rates I calculated prior here was between 0.1% - 0.5%. That number has since increased as total number of failures have increased. An upper limit of 1% now is probably reasonable. That calculation accounts for the number of forum members reporting to own an M3 as well as the total public production numbers of the car.

What I wonder is how many cars have worn bearings and how much wear will they endure before failure? I don't doubt that 1% failure rate and I dont think my car was going to blow uo next week even though there was a lot of wear where I didn't expect it...around the edges and parting lines. However, it seems about 75% of the people here who've swapped have documented some degree of abnormal wear, but does that mean that failure is definitely in the offing?

[swamp2]

Originally Posted by Doc Oc

What I wonder is how many cars have worn bearings and how much wear will they endure before failure? I don't doubt that 1% failure rate and I dont think my car was going to blow uo next week even though there was a lot of wear where I didn't expect it...around the edges and parting lines. However, it seems about 75% of the people here who've swapped have documented some degree of abnormal wear, but does that mean that failure is definitely in the offing?

Failure rates continue to be an increasing function and obviously depend on mileage. Unreplaced, obviously, all bearings will likely fail.

The irony of all of the swapping is that folks are replacing the bearings with either unproven products/coatings/treatments or even bearings with less clearance. At best, replacement is being done with identical clearances. Also, I suspect most folks are not doing a full blueprinting/documentation type of bearing replacement...

More to your question, I've not seen anyone able to look at a bearing and provide a lifespan remaining estimate...

[Doc Oc]

Originally Posted by swamp2

Failure rates continue to be an increasing function and obviously depend on mileage. Unreplaced, obviously, all bearings will likely fail.

The irony of all of the swapping is that folks are replacing the bearings with either unproven products/coatings/treatments or even bearings with less clearance. At best, replacement is being done with identical clearances. Also, I suspect most folks are not doing a full blueprinting/documentation type of bearing replacement...

More to your question, I've not seen anyone able to look at a bearing and provide a lifespan remaining estimate...

I'm worried I may be one of those people. VAC lists their new bearings as extra clearance and rg measured them to be thinner, but that's all I really had to go by. VAC couldn't even tell me what material was under the coating, just that they were custom made for them by Mahle-Clevite. Now I have no idea what to look for on uoa's. I do know that temps are slightly down and the car runs like a raped ape but there's still a little voice in my head telling me whatever forces were at work that damaged my old bearings are still there. Worrisome.

One other question. Do you (or anybody else) know how many registered m3 owners are here? From the registry it looks like we have about 75 failures. I thought I read once that we had about 4500 members. If that is correct then we are closer to 2% than 1% aren't we?

[Killerfish2012]

Originally Posted by Doc Oc

One other question. Do you (or anybody else) know how many registered m3 owners are here? From the registry it looks like we have about 75 failures. I thought I read once that we had about 4500 members. If that is correct then we are closer to 2% than 1% aren't we?

Keep in mind that the raw failure rate is still quite deceptive. The failure rate does not take into account, abuse, and or neglect. Instead it takes each failure event and treats them the same, i.e well maintained naturally aspirated set up. What's wrong with doing this? You might ask? Well look around this section, and you will see threads inquiring about running 9lbs of boost, and methanol injection. Take a second look at the personal for sale engine/parts section, and you will see quite a few threads selling supercharger kits. How many of the cars that had these superchargers pulled are now out on the market converted back to naturally aspirated form? And before anyone argues the effect of boost on the bearings, there is no doubt that the Forced induction group sees a much higher failure rate, than naturally aspirated. It's practically asking for it.

[Killerfish2012]

Originally Posted by Doc Oc

One other question. Do you (or anybody else) know how many registered m3 owners are here? From the registry it looks like we have about 75 failures. I thought I read once that we had about 4500 members. If that is correct then we are closer to 2% than 1% aren't we?

One last thing, I failed to touch on the woes of ignoring owner neglect when looking at the failure rate. Since some misguided "engine experts" on here love to cross compare BMW to other brands, but fail to talk about the large gap in maintenance behavior, consider this analogy. A typical Honda, has the oil and filter changed every 3,000 miles. So by 45K miles when cars start to exchange hands, the Honda has had 15 oil and filter changes. The BMW owner who listened to the dealership changed the oil and filter when the oil analyzer indicated. Typically at 15K miles. So at the same mileage as the accord, it's seen only 3 oil and filter changes! Of course the bearings from both these vehicles would look radically different.

[pbonsalb]

It is not neglect to follow factory maintenance. Unless the factory has screwed up. Some think it has, both in building and maintaining these motors.

[Doc Oc]

Originally Posted by Killerfish2012

Keep in mind that the raw failure rate is still quite deceptive. The failure rate does not take into account, abuse, and or neglect. Instead it takes each failure event and treats them the same, i.e well maintained naturally aspirated set up. What's wrong with doing this? You might ask? Well look around this section, and you will see threads inquiring about running 9lbs of boost, and methanol injection. Take a second look at the personal for sale engine/parts section, and you will see quite a few threads selling supercharger kits. How many of the cars that had these superchargers pulled are now out on the market converted back to naturally aspirated form? And before anyone argues the effect of boost on the bearings, there is no doubt that the Forced induction group sees a much higher failure rate, than naturally aspirated. It's practically asking for it.

I don't disagree with any of this believe it or not. I can't believe people are running boost through this engine without any modifications. Our static compression ratio is 12:1. Adding 8 pounds of boost to that is going to bring the effective compression ratio up over 18 lbs. That is insane and I dont know how they aren't detonating like crazy. I've supercharged a couple of my corvettes in the past. First step was to change the head gasket to drop the cr into the 8.5:1 range. Even then we would run some retard on pump gas at anything over 8-9 lbs of boost. And a large contigent of vette guys wouldn't boost at all without rebuilding with forged guts. I'm blown away that these sc'd cars last at all and that really is a testament to the engine build and ECU quality.

[Doc Oc]

Originally Posted by Killerfish2012

One last thing, I failed to touch on the woes of ignoring owner neglect when looking at the failure rate. Since some misguided "engine experts" on here love to cross compare BMW to other brands, but fail to talk about the large gap in maintenance behavior, consider this analogy. A typical Honda, has the oil and filter changed every 3,000 miles. So by 45K miles when cars start to exchange hands, the Honda has had 15 oil and filter changes. The BMW owner who listened to the dealership changed the oil and filter when the oil analyzer indicated. Typically at 15K miles. So at the same mileage as the accord, it's seen only 3 oil and filter changes! Of course the bearings from both these vehicles would look radically different.

Yup, I've said many times that the people I talk to around here blame oci more than clearance. They say the number one bearing killer is dirty oil, and tight clearances only magnify the problem. Regardless the blame still lies with BMW.

[admranger]

Originally Posted by Killerfish2012

A typical Honda, has the oil and filter changed every 3,000 miles.

The only Hondas that get 3k mile oil changes are their lawnmowers...

Other than enthusiasts, who are not 'typical' owners of Hondas or BMWs, most people treat their car as an appliance. Oil gets changed when they get around to it, not on some 3k miles change schedule (that is wasteful anyway if you are using synthetic oil). Honda cars are now ~6k miles between changes if google is to be believed. Hondas have a service life monitor for oil like ours do.

I do agree that our 15k mile frequency is silly and likely not in the best interest of the life of the engines.

[Doc Oc]

Here is a better picture of the parting line wear my old bearings experienced. Any ideas?

[Killerfish2012]

Originally Posted by Doc Oc

Here is a better picture of the parting line wear my old bearings experienced. Any ideas?

http://www.agkits.com/bearing-failure-analysis.aspx

Look at the pictures for Corrosion. Chemical corrosion from acids in oil due to excessive oil change intervals.

[Doc Oc]

Originally Posted by Killerfish2012

http://www.agkits.com/bearing-failure-analysis.aspx

Look at the pictures for Corrosion. Chemical corrosion from acids in oil due to excessive oil change intervals.

Thanks....I looked at that link awhile back and thought corrosion was the closest but no mention of parting line wear in the article.

[pbonsalb]

I do not believe corrosion would affect only the parting lines. Any theory to go with this?

[Killerfish2012]

Originally Posted by Doc Oc

Thanks....I looked at that link awhile back and thought corrosion was the closest but no mention of parting line wear in the article.

There is parting line wear in the corrosion picture (look to the left side of the bearing), other wise it looks almost like the normal wear. Corrosion, like normal wear is a properly installed, in spec bearing, but has had long oil change intervals.

[Doc Oc]

Originally Posted by pbonsalb

I do not believe corrosion would affect only the parting lines. Any theory to go with this?

From what I've read it is usually caused by over torqued bolts or rod stretch. I was hoping some of the bearing experts would chime in but haven't had any luck. I'm hoping that new, properly torqued bolts have fixed the problem but there's no easy way to find out.

[pbonsalb]

My bearings at 60k had copper showing at the parting line areas only. I am glad I changed them. I won't be doing them again until I have at least 110k miles on the car. I have 67k now and at the 6k per year I drive this car that will be another 7 years. But I will post the results then if I still have the car.

[Doc Oc]

Originally Posted by pbonsalb

My bearings at 60k had copper showing at the parting line areas only. I am glad I changed them. I won't be doing them again until I have at least 110k miles on the car. I have 67k now and at the 6k per year I drive this car that will be another 7 years. But I will post the results then if I still have the car.

You don't have a PIC do you? I'd love to compare them to mine. Also, if I remember you went wpc right? Have you done a uoa yet?

[pbonsalb]

No UOA. I took some pics at the time and posted them but they did not come out well due to the lighting.

[squartus]

Here are mine from 30k when I changed them to WPC treated bearings when I supercharged engine.

Looks worse in person but yea got wear around the edges on many, this is from 10w60 and 7.5k oil changes. Non tracked car, had a bpm tune on it for 3k before bearing change and axle back exhaust.

[Doc Oc]

Great pics, thanks. Our uppers look about the same but I've got a little more wear on the lines. Your lowers are much worse than mine though from what I can tell. Mine had no wear at all. Weird. Did you go with stock bolts?

[squartus]

I went with ARP bolts as was recomended at the time. This was back in october before anything was brought up about bore distortion perhaps being an issue or not.

[Doc Oc]

Originally Posted by squartus

I went with ARP bolts as was recomended at the time. This was back in october before anything was brought up about bore distortion perhaps being an issue or not.

I went with ARP too. VAC had a kit with custom bearings and bolts. They say the bolts are custom to them and are not the 2000 or 625. Don't know if that is good or bad honestly. How many miles do you have now and have you done a uoa?

I was worried about the bore distortion too. Hard to find any solid info.