[fatty335]

I know this has been openly considered/discussed before by others but nobody has actually gone through with it. While the general consensus has been "if it ain't broke, don't fix it," since it's a relatively uncomplicated job and I plan to keep my N55-equipped 335i well past 100K miles, I'm going to do it. This car, like many from the early 2010s-era, was subjected to 15K OCIs which was probably not conducive to extended bearing life. I also run an MHD 1+ on what is an essentially FBO minus cat back car - again, probably not conducive to extended bearing life.

As we all know, bearing replacement is a pretty common maintenance procedure in S65 and some other BMW engines. I plan to swap identical OE bearing shell combos: violet/blue or yellow/red depending on what I find stamped on the crank. I, like most shops swapping S65 bearings OE for OE, do not plan to check each clearance with platigauge. Additionally, I will use new, OE torque-to-yield rod bolts and resist the urge to use ARP or anything else that might even slightly alter the factory clearances.

I'm collecting parts now and am curious to see how worn my 72,000+K N55 bearings are. Not sure if I'll get to this job before going on a fairly long trip in a month but, it's going to happen...

[Joebie]

Have you ever done an oil analysis?

I'd be curious to see what an oil analysis tells you vs what you actually see once you get the bearings out.

If the oil analysis accurately predicts what you end up seeing on the bearings, that may give hope to fellow N55 owners that they can just periodically send in oil samples to see if their bearings are failing and catch/fix it early.

I think your plan to use OE parts and not plastigauge it is acceptable. It's not like they're plastigauging every engine in the factory either. If you used aftermarket stuff thats obviously a different story.

Good luck! You say its relatively uncomplicated which I suppose it is, but that's still a bigger task than 99% of this forum would ever try. Take lots of pics!

[hassmaschine]

Ya'll are crazy in this forum. There's basically zero reason to be concerned about N55 rod bearings.. but here we are. :|

[9krpmrx8]

^ This. But hey it's your money and your engine to risk so do it to it.

[fatty335]

Originally Posted by Joester

Have you ever done an oil analysis?

I'd be curious to see what an oil analysis tells you vs what you actually see once you get the bearings out.

If the oil analysis accurately predicts what you end up seeing on the bearings, that may give hope to fellow N55 owners that they can just periodically send in oil samples to see if their bearings are failing and catch/fix it early.

I think your plan to use OE parts and not plastigauge it is acceptable. It's not like they're plastigauging every engine in the factory either. If you used aftermarket stuff thats obviously a different story.

Good luck! You say its relatively uncomplicated which I suppose it is, but that's still a bigger task than 99% of this forum would ever try. Take lots of pics!

No oil analysis done during my ownership so we won't have that data point.

Originally Posted by 9krpmrx8

This. But hey it's your money and your engine to risk so do it to it.

Money...yes. But I'm not sure I follow you when you say "your engine to risk." This is a very common procedure for the S65 crowd with some engines already having two or three sets of bearings replaced. I have also seen this done on a number of N54s...one you should be able to find on a pretty popular site without too much searching (project car). I suppose a careless approach could result in damage (i.e. incorrect torque applied or incorrect color combo installed) but it really isn't that difficult a procedure.

[Pladi]

Originally Posted by fatty335

I know this has been openly considered/discussed before by others but nobody has actually gone through with it. While the general consensus has been "if it ain't broke, don't fix it," since it's a relatively uncomplicated job and I plan to keep my N55-equipped 335i well past 100K miles, I'm going to do it. This car, like many from the early 2010s-era, was subjected to 15K OCIs which was probably not conducive to extended bearing life. I also run an MHD 1+ on what is an essentially FBO minus cat back car - again, probably not conducive to extended bearing life.

As we all know, bearing replacement is a pretty common maintenance procedure in S65 and some other BMW engines. I plan to swap identical OE bearing shell combos: violet/blue or yellow/red depending on what I find stamped on the crank. I, like most shops swapping S65 bearings OE for OE, do not plan to check each clearance with platigauge. Additionally, I will use new, OE torque-to-yield rod bolts and resist the urge to use ARP or anything else that might even slightly alter the factory clearances.

I'm collecting parts now and am curious to see how worn my 72,000+K N55 bearings are. Not sure if I'll get to this job before going on a fairly long trip in a month but, it's going to happen...

You will see some negativity but i can guarantee you that everyone who cares about their N55 is as excited as you are to see the results.

You are not risking anything. You have to be very particular about the process and making sure every other bolt in there including the oil baffle is torqued properly.

[hassmaschine]

You should preventatively replace the engine too. You know, just in case.

[SnapCoupe]

Oh boy oh boy this thread is going to be a wild ride.

OP, I am looking forward to seeing the results when you pull the old bearings out. Mine spun around the 80k mile mark, and while I feel as if it isn't a super common occurrence, there are enough documented cases around here to arise concern. Thank you for taking the time to document and post this info!

[bbnks2]

In for results. No harm done if you do the work right. BMW bearings are expensive though. It's like $30 per shell.

[9krpmrx8]

When I say risk, I mean that there is always a risk when doing this job, especially if the person doing it, is not experienced. I assume you haven't done this before, but if you have, then rock on. I look forward to your findings.

[Welcome to NBA Jam]

Why would you not use a plasti gauge? You're already in there. It's not much of an extra step to ensure you've got the correct clearances.

[dleccord]

Originally Posted by bbnks2

In for results. No harm done if you do the work right. BMW bearings are expensive though. It's like $30 per shell.

just for reference, how much would the same go for a honda or toyota?

[Pladi]

Originally Posted by dleccord

just for reference, how much would the same go for a honda or toyota?

BMWs are not special.. bearings are made by vendors for multiple makes.. Now if you are asking what BMW charges because they can compare to other makes thats a different story

[feuer]

Originally Posted by Welcome to NBA Jam

Why would you not use a plasti gauge? You're already in there. It's not much of an extra step to ensure you've got the correct clearances.

And what he is going to do if clearance isn't "correct" ? Is he going to have custom made bearings to get the clearance spot on? Or put electrical tape between rod and bearing to making tighter? Or sand it down to make it looser? Most defiantly not. He is removing bearing size X and replacing it with another bearing of identical size X. So why plastiqauge? Is absolutely purposeless for what he is doing as he wont be able to correct the issue without removing the crank, machining the crank, getting larger bearings and then plastigauge to check if clearances are ok. This is main reason why shops aren't doing it either. Isn't because they are careless.

[Pladi]

Originally Posted by feuer

And what he is going to do if clearance isn't "correct" ? Is he going to have custom made bearings to get the clearance spot on? Or put electrical tape between rod and bearing to making tighter? Or sand it down to make it looser? Most defiantly not. He is removing bearing size X and replacing it with another bearing of identical size X. So why plastiqauge? Is absolutely purposeless for what he is doing as he wont be able to correct the issue without removing the crank, machining the crank, getting larger bearings and then plastigauge to check if clearances are ok. This is main reason why shops aren't doing it either. Isn't because they are careless.

Lol ! And try put plasti gauge on oil covered jurnals ! Ur gonna get nice readings. Covered in oil its gonna be tough to apply. Cleaning that area its hard oil is everywhere. So ya. I think the OP is making the right choice. Not to try and gauge.

[Ozzie335i]

fatty, for the rest of us (ok, me), please do an oil sample and have Blackstone test it. If bearing wear is minimal and there appears to be no scoring, as fuer said, do it, the heck with plastiguaging.

One thing to be sure of though... there was a guy on the N54 threads that got a few undersized, yeah thicker, bearings that when he tried to turn the crank it would not turn. Even though the boxes were marked as the same size, the bearings within were different. He sorted it out before he put the oil pan back on. Something free in your effort, the likely leaky oil pan no longer will be.

[hassmaschine]

Pretty sure a plastigage kit costs less than $10. It would be even more foolish to unnecessarily replace the bearings and not at least check the clearance..

[fatty335]

Originally Posted by Ozzie335i

fatty, for the rest of us (ok, me), please do an oil sample and have Blackstone test it. If bearing wear is minimal and there appears to be no scoring, as fuer said, do it, the heck with plastiguaging.

One thing to be sure of though... there was a guy on the N54 threads that got a few undersized, yeah thicker, bearings that when he tried to turn the crank it would not turn. Even though the boxes were marked as the same size, the bearings within were different. He sorted it out before he put the oil pan back on. Something free in your effort, the likely leaky oil pan no longer will be.

Sorry, Ozzie - the timing is not going to work out for the oil sample before I'll be digging into this. And I am aware of the incorrect size issue incident you mentioned...which is a big reason I'm sticking with OE vs. King or another aftermarket manufacturer.

*UPDATE: As of this morning, all parts have been purchased and are about a week out. I ended up ordering a complete set of WPC-treated violet/blue and yellow/red shells so I'll have whatever combo my crank requires BEFORE cracking it open. Other items on the list for anyone else considering this job:

oil pan gasket: 11137600482
set of pan bolts: 11132210959
oil level sensor gasket (why not): 12611744292
rod bolts: 11247589671
oil pump bolt kit: 11412165397
oil pump-to-sump o ring: 11417527092
4 oz redline engine assembly lube

I also bought a torque angle gauge tool in order to more accurately torque the rod bolts. All told (when 6 of the 12 bearing shells have been returned), this job will cost ~$550 and a day in the garage. For me and for how long I plan to keep my car, this is cheap insurance - if for no other reason than to determine how fast my car is going through the rod bearings. Stay tuned...

[hassmaschine]

Why cant you collect a sample of the oil when you drain the engine? Just keep some in a 1 qt jug and order a testing kit.

[fatty335]

Originally Posted by hassmaschine

Why cant you collect a sample of the oil when you drain the engine? Just keep some in a 1 qt jug and order a testing kit.

I certainly could, however, the information we could glean from it would be of limited utility as I am on almost new oil & filter (just the way the timing worked out in this case).

[bbnks2]

There is nothing a UOA is going to tell him that a visual inspect inst already going to be able to...

[lwgrenier]

Originally Posted by bbnks2

There is nothing a UOA is going to tell him that a visual inspect inst already going to be able to...

Right but I think the other guys want to know if the UOA is accurate so they can monitor bearing life with analysis rather than opening up the engine.