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.
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.
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!