[rhouse181]

Hey everyone, I thought that I would document every aspect of my rod and main bearing replacement to help all of us in the future. First off, my car is a 2000 with 97k miles on it. She is babied until the oil temps are proper (not just until the yellow warning lights go out, but a full 150 degrees at least). Build date 05/00...

After getting the car fully warmed up, I noticed a slight knocking sound when listening under the car right behind the front wheels. It was not noticeable when listening to the top of the motor. After reading many posts on this great forum, decided to take her in and get the bearing swapped. I almost cried today when I saw how many pieces the beast was in. They had a custom build support fabricated so the motor could be suspended, pretty cool (ill have some more pictures tomorrow).

After pulling the rod and main bearings, we found that the rod bearings were subjected to significant lateral loading. As you can see in the pictures below, the top bearing shell has worn through the top polished aluminum layer (the top is subjected to most of the wear). Luckily, the copper isn't exposed, saving the crank from any scoring. Please see the photo below.

When the mains were pulled, the bottom shells looked pretty good with no significant signs of wear. They will be replaced anyways because the whole freakin motor is apart. I'm going to the shop again tomorrow for further pictures and analysis. We're going to boroscope the cylinder walls again to see if we can match up the minor scoring with the severely worn bearings. Hopefully, there will be a correlation there and not a significant ring issue.

- Randall House

 

[Flyin-m5]

Cool stuff. Can't wait to see the other piks. Cool that it can be done with music maker still in the car! :M5launch:

 

[Kaleb]

...wipes off keyboard...

Sorry, mangasm. Brings back memories of when I built a Nissan VG30E from scratch a few years ago. You haven't lived until you build a motor.

 

[oUSC]

where did you take it?

I think I may be facing the same issue and am in Houston as well. Where did you end up taking your car? I would be interested in know how things turn out and if you were satisfied with the work.

 

[Lscman]

Great post. Thanks for taking the time to document the bearing condition with pics. Your bearings look like those pulled from an old car that had cheap oil in it. This accelerated rod bearing wear rate on S62 is seemingly common and perhaps even typical, no matter what service interval is used with premium oil. Time at elevated RPM slowly eats the bearings.

I suspect your mechanic is now checking each rod for roundness because an audible knock will almost always pound the rod into an egg shape. A simple $50 shop machinist tool kit can be used or fancy instruments can be used. You could get lucky and discover no rod damage, especially if your hearing is extremely sensitive and you caught it early. More rod bearing closeups would be greatly appreciated.

Looks like a little extra work was performed, as your timing chain is hanging limp. This will impact job cost. I suspect this was needed to pull the #1 main bearing for inspection. Mains do not seem to wear prematurely, as you noted. The #1 is always the quickest to wear due to serpentine and timing chain loading. This provides yeat another datapoint suggesting the S62 main bearings generally outlast the motor (200K+ mi).

The hand-built jig to hang the motor on is a nice option. I've seen them built from 4x4 oak and other things, perched on the strut towers. A regular $100 shop crane from Harbor Freight can be used also, but it somewhat impedes working below. Another option is a "come along" hanging from asteel garage support beam, but this requires hood removal.

If you caught this knock in time, this will be the first report where an owner heard the noise and saved the motor from throwing, pounding or bending a rod.

The mileage reading under 100K is a wakeup call to other's waffling on proactive $1K to $2K rod bearing replacement. Saving a rod from becoming out-of-round from knock will essentially reduce the cost of repair by about $5K to $10K. Saving a rod from being hurled through the block can save $15K to $25K.

 

[Lscman]

PS:

You might want to iexchange your stock swaybar for an Eibach 28mm swaybar while you're in there with the subframe off. This opportunity takes an 8hr labor job to 0 hrs.

Hope they check the rod big ends for roundness. Fingers crossed....

Please let us know final job cost.

Please confirm why lower timing chain gear on crank was removed.

 

[rhouse181]

Lscman,

It wasn't really a knock where you could hear the rods banging around, but you could hear the slop in the rods when the motor was idling. At most, it was a tiny ticking sound. Any load whatsoever and the sound would go away. I've always been extremely sensitive to the noises my motor makes, and so far (still keeping my fingers crossed) the rods looks like they can be saved.

The timing chain was pulled so all the main bearings could be swapped out. You needed to remove the timing chain to get enough slop in the crank so the top of the main bearings could be slid out as well.

Ha, i wish I had money to throw in a swaybar, but this one is going to be expensssssive.... I was quoted $2100 to get the main and rod bearings, all new bolts, oil pump and solinoids refreshed. However this will go up because I've tacked on new valve cover gaskets, my injectors are going to be bench tested for flow, the oil jets that spray the connecting rods are going to be bench tested for flow, all new shifter bushings with an e60 545 shift rod, center link ball joints, and thrust arm bushings to the equation because the labor to take everything all apart is already spent.

I'm going to use a ball micrometer to measure the bearing shell widths tonight and compair them to new shells. The more data I can collect, the better for all of you in the future! I'll have more pictures on the way later tonight...

I highly recommend anyone with some miles on their motor to pony up the cash, then you'll have a happy s62 for the next 100k miles!

- Randall House

 

[xr4tic]

So what is the root cause?

Poor lubrication system? Bad bearing design?

 

[rhouse181]

Search for the thread "bearing wear above 6000rpm." The issue is throughly discussed in that thread...

- Randall

 

[Wi_KeD_M5]

Search for the thread "bearing wear above 6000rpm." The issue is throughly discussed in that thread...

- Randall

Just a tip for any one doing this search. Shorten it to "bearing wear". Putting "bearing wear above 6000rpm" led me right back to this thread. :hihi:

Of the search results, I think the post started by gsfent is the one.

 

[xr4tic]

yep, I had the same thing happen with the search.

This looks like it:
http://www.m5board.com/vbulletin/showthread.php?t=93183&highlight=bearing+wear

 

[Kaleb]

Haha we all searched. Put a space between 6000 and rpm and then you'll find stuff I bet.

 

[xr4tic]

I just read through that post. I was wondering why the surface of the rod caps didn't look smooth, looks like they are indeed cracked caps, so the bearings can be replaced without removing the rods.

I just find it difficult to beleive that RPM is the main reason for the problems.

There are many 4 cyl motors that have higher HP/liter ratios, mainly because they run much higher RPMs. I know that we have V8s, but I would think the load per cylinder/rod/rod bearing would be equivalent.

 

[Lscman]

xr4,

If the lubrication system was real marginal or seriously-flawed, these motors would not tolerate severe duty when new. This is not the case. Failures do not occur until the rod bearings see full lifecycle.

Rod and main bearing lubricity & premature wearout skyrockets on V8's with elevated RPM capabilities. Very few V8 motors can tolerate 7K+ RPM. This was learned when racers began putting cams in motors to wind them tighter. The problem is huge for off-shore boat racers. This widely-known phenomenon applies to engines from Germany too.

The S62 may have some other design weaknesses relating to rod lubricity that contribute to this problem, but realize the M62 (limited to 6000 RPM) is largely bulletproof to 200K+ mi with 100% identical bearings. The glaring difference is RPM. More horsepower & modest differences in stroke will not cut life in half. This RPM issue also somewhat obvious after reviewing the disturbing ratio of folks who lost S62 motors with chips vs non-chip. This is not rocket science, as GM and Ford fanatics running chips in street cars see similar failures at low mileage. When you explore race-like RPM limits, you need to adhere to race-like service strategies.

 

[Lscman]

Lscman,

It wasn't really a knock where you could hear the rods banging around, but you could hear the slop in the rods when the motor was idling. At most, it was a tiny ticking sound. Any load whatsoever and the sound would go away. I've always been extremely sensitive to the noises my motor makes, and so far (still keeping my fingers crossed) the rods looks like they can be saved. ...........

Worn out rod bearings and/or ANY related audible sound MANDATES rod big end measurement for out-of-round conditon. That check is not optional. The tools can be bought at Harbor Freight for $50 and the check might take 1/2 hr. Putting the motor together without knowing rod condition would be foolish.

 

[alquazi]

I also have 05/2000 build date M5 with over 225k km which is about 135k miles. I have spent a lot of time(miles) over the 6000 rpm range and I think this is what I should be looking into. Where is the best place to get parts for such a job and do you know how much the parts cost?
Thanks for this informative post,
Al

 

[Lscman]

I also have 05/2000 build date M5 with over 225k km which is about 135k miles. I have spent a lot of time(miles) over the 6000 rpm range and I think this is what I should be looking into. Where is the best place to get parts for such a job and do you know how much the parts cost?
Thanks for this informative post,
Al

Go to realoemdotcom to get representative cost of these parts in US dollars.

For this direct replacement exercise, you should NEVER deviate from OEM BMW factory bearings. The bearings should be ordered after the original one's are inspected and factory markings (size) documented and confirmed for each upper and lower shell. The bearings come in fractional undersizes for hand fitment to each crank journal. It is entirely possible to find various size bearings used in a single motor from the factory, in order to provide optimal clearances with the crank. You should buy the exact same to ensure original tolerances are maintained. This generally the best policy because it ensures you're duplicating the original M factory specs, unless the crank is removed and everything is mic'd. You really aren't gonna do much better than the factory, so cheat off their shell sizing selections. Unless you spin a bearing or throw a rod, the M crank journal will be extremely close to new size.

 

[Lscman]

.............Luckily, the copper isn't exposed, saving the crank from any scoring. ...........

Clevite 77 bearings and clone variants used in modern engines have no copper colored base layer to speak of. This has been the case with motors using "performance grade" OEM bearings since around 1980. You can google to get related info. They will wear down to base metal with no copper color showing, so your subjective, optimistic diagnosis may not be accurate.

Your bearings are worn a lot from what I can see. If it was making noise, they are worn thru all bearing material and therefore oil control was probably very poor. The premium BMW crank is surely tough and wear-resistant, so it is probably not scored and likely within spec.

 

[THRILOS5]

...wipes off keyboard...

Sorry, mangasm. Brings back memories of when I built a Nissan VG30E from scratch a few years ago. You haven't lived until you build a motor.

+1 on the feeling of building the VG30

does anyone know if there was a rod bearing redesign like they did with the e46 m3? BMW had to recall and reinstall new bearings in almost every '01 m3

 

[rhouse181]

Update #1

Hey all, just returned from the shop and there has been significant progress. All the rod big ends were measured when the bearing caps were pulled. Luckily, every rod end is still true.

With that being said, there were 4 bearings with decent wear (cylinder's 1,5,2,7) that we are trying to match with the 4 cylinders with minor scoring. As for the main bearings, they all looked great. Therefore for proactive replacements, I don't think it is necessary to pay for the mains.

Things are beginning to get pieced back together. The upper oil pan has been replaced. We had an oil discussion (i know this is a sensitive topic), but 2 intriguing points got brought up. Most of the wear on the lubricated parts comes from the first 2 minutes of operation. The TWS is somewhat suspicious when it comes to lubricity at startup. Also, the TWS was invented in the mid-90's utilizing the very first round of synthetic oil additives (i am in the petrochemical benchmarking industry and did a little extra research with my friend from Exxon). Compared to new full synthetic, the TWS has multiple compounds that breakdown extremely fast under high shearing temperatures (think bearings). I think the breakdown of these additives are one of the attributing factors to the carbon build-up issue.

Call me crazy, but I'm thinking about running Mobil 1 15w-50 for its better protection against cold start wear. Also, Mobil 1 is more stable and there aren't any extra additives to breakdown. We'll see if this starts any oil consumption problems (i had 0 oil used between changes with the TWS). This is a side test...

Here are some pictures. First one is of all the used bearing shells, rods on top and mains on bottom. You can see the 4 used rod shells pretty easy. Second one is of oil pump solenoids, sensor, and chain drive sprocket. Third is the actual oil pump. Fourth is the upper oil pan installed with oil pump drive chain still dangling. Fifth is the motor support bracket. Last is a nice clean lower oil pain.

- Randall House