2009 E90 DCT - 96K Miles - Original Rod Bearings changed today.

Did you do your rod bearings based off results from an oil analysis? Or did you just do the work based off feedback from other threads. I have a 2009 DCT with 92.5k miles and still on original bearings.

happydude wrote

Did you do your rod bearings based off results from an oil analysis? Or did you just do the work based off feedback from other threads. I have a 2009 DCT with 92.5k miles and still on original bearings.

To clarify the thread title, the car had 96K miles when I bought it a few months ago, it now has 99.7K miles so that was my typo if that matters. I did the blackstone test right after I got it, but I knew that not having long-term consistent oil tests is essentially worthless, but figured what the hell.

Make sure you read the comments carefully before looking at the lead #... when I got it back, we suspected some sort of additive in the fuel, because it was SO high.. so I wouldn't use this as a barometer for comparison purposes, because I had one test after God knows what happened before. Car was in great shape otherwise.

Thanks for posting OP. 99k is a fair milage and clearly good timing to get some new shells in. That deep scratch I guess from dirt, assumingly your shop checked crank to still be nice and smooth.

You wanne post here as well just to keep things collected in one spot? https://www.m3post.com/forums/showthread.php?t=1253084

TrAcK TRaP wrote

Looks like they were good for another 96K miles.. That much change after replacing? Most of them your brain created trust me on that

You can't be serious....

happydude wrote

Did you do your rod bearings based off results from an oil analysis? Or did you just do the work based off feedback from other threads. I have a 2009 DCT with 92.5k miles and still on original bearings.

IMO it's probably best to just change them.... with the higher mileage, it's probably going to be similar to mine based on the clearance issue.. feels so much better to have it done.

wfdeacon88 wrote

IMO it's probably best to just change them.... with the higher mileage, it's probably going to be similar to mine based on the clearance issue.. feels so much better to have it done.

Thanks for sharing! Greatly appreciated. I will be changing the oil soon and will get an analysis done to see if it shows similar to yours. Regardless I will definitely look into getting the rod bearings and engine mounts!

happydude wrote

wfdeacon88 wrote

IMO it's probably best to just change them.... with the higher mileage, it's probably going to be similar to mine based on the clearance issue.. feels so much better to have it done.

Thanks for sharing! Greatly appreciated. I will be changing the oil soon and will get an analysis done to see if it shows similar to yours. Regardless I will definitely look into getting the rod bearings and engine mounts!

good call. FYI that oil analysis I posted shouldn't be used as a barometer of comparison, just in case it's not messed up, we don't know what oil was used, how overdo it was, and if fuel additives skewed it .. looks like mine went all the way down through so many layers, so who knows.

wfdeacon88 wrote

good call. yeah that oil analysis is odd, we don't know what oil was used, how overdo it was, and if fuel additives skewed it .. looks like mine went all the way down through so many layers, so who knows.

My M3 has been in the family since new and I have all service records and document all the service I perform. Last time I had leaded gas in the car from a track event was about 6 years ago and it was only a few gallons so that should be out of the system by now. Only other additive I have added would be the Chevron Techron 12oz I added a few months ago. So hopefully that won't throw off the analysis too much.

Looks like they were good for another 96K miles.. That much change after replacing? Most of them your brain created trust me on that

Fake news.

No, not in my brain, deadly serious. I can't even describe how I tracked the noises and driving feel in my head, but I did. it's night and day. now, whether or not it's mounts or RB, I don't know, but I do know it's a different car in terms of driveability.. I am extremely OCD about the little things, so I know when they change.

Most of the change you're experiencing would be from the new mounts. If your old ones were really shot then it can feel like you're driving a whole different car. Good that you had new ones installed.

Your old bearings look pretty poor but not abnormally poor for these engines- pretty consistent for the mileage. Compared to the newer 702/703, old style bearings usually appear worse than they really are. Don't worry about the grooves in the bearings. They're from foreign particles and the bearings did their job to embed the material in the bearing babbit instead of scoring the crank journal. Usually don't see that much foreign matter damage though, even at those miles...I'd make sure your engine seals are kept up and watch your oil change intervals. Use good OEM grade filters like Mahle or Mann.

deansbimmer wrote

Looks like they were good for another 96K miles.. That much change after replacing? Most of them your brain created trust me on that

Fake news.

No, not in my brain, deadly serious. I can't even describe how I tracked the noises and driving feel in my head, but I did. it's night and day. now, whether or not it's mounts or RB, I don't know, but I do know it's a different car in terms of driveability.. I am extremely OCD about the little things, so I know when they change.

Most of the change you're experiencing would be from the new mounts. If your old ones were really shot then it can feel like you're driving a whole different car. Good that you had new ones installed.

Your old bearings look pretty poor but not abnormally poor for these engines- pretty consistent for the mileage. Compared to the newer 702/703, old style bearings usually appear worse than they really are. Don't worry about the grooves in the bearings. They're from foreign particles and the bearings did their job to embed the material in the bearing babbit instead of scoring the crank journal. Usually don't see that much foreign matter damage though, even at those miles...I'd make sure your engine seals are kept up and watch your oil change intervals. Use good OEM grade filters like Mahle or Mann.

Thank you! yeah I buy the engine mount comments now.. Good to know those did this much for driveability. Anything specific on the engine seals to make Sure I have them check? They inspected everything for damage and said it looked good inside, so I guess those foreign particles did their job as you said. Do you also recommend another oil change 500 miles from now or I can I wait until 1000-1500? Also, is it safe in your opinion to drive "normal" now after a hundred miles of making sure it's working? thanks again!

wfdeacon88 wrote

Thank you! yeah I buy the engine mount comments now.. Good to know those did this much for driveability. Anything specific on the engine seals to make Sure I have them check? They inspected everything for damage and said it looked good inside, so I guess those foreign particles did their job as you said. Do you also recommend another oil change 500 miles from now or I can I wait until 1000-1500? Also, is it safe in your opinion to drive "normal" now after a hundred miles of making sure it's working? thanks again!

Yes, you can drive normally. Some people want to flush out any assembly lubes shortly after this service but there's not much need. Assembly lube is just oil high in zddp/moly additives and dilutes in the rest of the engine's new oil. If anything it provides desirable extra anti-wear protection. The filter is supposed to remove any foreign particles from reassembly- you can/should change/inspect the filter in 500 miles but exchanging the oil is less critical.

Check the valve cover gaskets, oil separator seals, and especially the oil filter housing to block seal, and oil cooler loop. Those are the most common culprits and most higher mile cars we see are well neglected in these areas.

Some pics of my RB's: 2008 w/ 76k on them, multiple black stone reports claiming clean bill of health, safe trending etc.

*edit - can't seem to upload a pic from the app. wtf?!

94jedi wrote

Some pics of my RB's: 2008 w/ 76k on them, multiple black stone reports claiming clean bill of health, safe trending etc.

*edit - can't seem to upload a pic from the app. wtf?!

Did you use the attach button instead of the picture button? only the attachment icon works for me on the app.

94jedi wrote

wfdeacon88 wrote

Did you use the attach button instead of the picture button? only the attachment icon works for me on the app.

yep, going to have to do it the old fashioned way and link via photobucket lol

I just hit attach and select from gallery but maybe mine is unique

I hope my bearings look like that when they come out. It's got to feel good knowing that wasn't $2500 wasted!

Did you go with OEM motor mounts??

Pics finally worked lol

Can someone please shed some light here for me. What makes both of those sets of bearings bad and puts them at risk of failure soon? To me they look worn out, but there's plenty of metal left. Also how does wear of ones bearings correlate to failure on cars that had theirs fail at a low mileage?

Firm believer here that this whole thing is blown way out of proportions and vendors as well as shops are taking full advantage of it. Yes, there's failures, but I don't think sets pictured here are those.

Yugo wrote

Can someone please shed some light here for me. What makes both of those sets of bearings bad and puts them at risk of failure soon? To me they look worn out, but there's plenty of metal left. Also how does wear of ones bearings correlate to failure on cars that had theirs fail at a low mileage?

Firm believer here that this whole thing is blown way out of proportions and vendors as well as shops are taking full advantage of it. Yes, there's failures, but I don't think sets pictured here are those.

Rod Bearings should show virtually no wear at all. My shop was somewhat conservative before doing my car and said I should be fine but they would do it with no downside to the car and at a minimum peace of mind. They did not push me at all to do this.. it was all me. When they saw these bearings we were all saying thank goodness we did it... sure, they could have driven 20K more miles, but they were ripe for failure. plenty of evidence on here to prove it's not a total internet hoax and has some significant truth to it

Yugo wrote

Can someone please shed some light here for me. What makes both of those sets of bearings bad and puts them at risk of failure soon? To me they look worn out, but there's plenty of metal left. Also how does wear of ones bearings correlate to failure on cars that had theirs fail at a low mileage?

Firm believer here that this whole thing is blown way out of proportions and vendors as well as shops are taking full advantage of it. Yes, there's failures, but I don't think sets pictured here are those.

The entire bearing shell is not wearable material. You cannot simply look at a bearing and determine how much more "meat" there is. The shell's structural component is steel. The babbit (dissimilar wear surface) is lead/copper or tin/aluminum. The crank is steel. Once the very thin babbit layers wear down, these similar metals weld together and you get a spun bearing. Many bearings spin well before that while the crank is riding on the exposed copper. Engines fail due to one failed bearing. They don't all seize up at once. Failed engines usually have seven journals that look exactly like the OP's, except for one cylinder (or main) which spun and shows visible copper or steel.

It has been said hundreds of times over...You Can't know when your bearings are going to fail. You can't look at a used bearing and say "yep, that one was only good for another 4,296 miles"... All you can do is go through with the service and move on with the peace of mind. The general consensus as to why some fail early and some later is unfavorable vs favorable tolerance stacking.

Yes, I'm a believer because I run a shop and have a finger on the pulse of the issue. And that's not because I get money to replace abnormally worn bearings, but because I see the huge number of failures which are astronomically out of normal proportion. It's a thing. It's not normal. Owners can believe it or not, it doesn't matter to us shops. Consider how many failures have been averted by owners changing their bearings? I guarantee you that if nobody ever did another bearing change ever, then we'd stay just as busy selling more replacement engines instead.



FYI, this engine was obviously built with a favorable tolerance stack. This is how bearings should look coming out of an S65 (of any mileage):



Instead, we constantly see them coming out like this:

IanMan wrote

You can't be serious....

I am..

TrAcK TRaP wrote

I am..

Please give me whatever you are smoking. I'll quit my job tomorrow.

IanMan wrote

Please give me whatever you are smoking. I'll quit my job tomorrow.

3 friends (none forum members) 2 cars over 120K miles they drive harder than you for sure no single issues. 1 car 143xxx miles only 1 TA replaced no other issue. And guess what? He revs the shit out of it. When I asked them if they replaced the Rod Bearings you know what they said? HUH? WHAT BEER?