E90 170k rod bearing question

[tdott]

Originally Posted by Helmsman

Facts to back it up in this particular case would be that it run for 170k miles with shells coming out ok, assuming this is the case.

If you think those bearings will look "ok", then your opinion isn't worth much to me. I'm willing to bet there is a lot of cooper showing.

Originally Posted by Helmsman

I'm aware that 3rd party "non extended" shells like ACL are a tad more open which I'd view as perfect here to compensate for possible maximum shell thickness, with lead surface as a bonus.

Saying "a tad more open", when we are talking 1/1000th of an inch that matter, shows your level of knowledge on the subject, or lack there of.

Originally Posted by Helmsman

The 702/703 is slightly more open, thought that was a well known fact.
.

BMW Published Numbers, they don't state which bearing it is for:
Minimum clearance: 0.0004 inch
Nominal clearance: 0.0009 inch
Maximum clearance: 0.0013 inch

088/9 measured clearance:
Nominal Rod Bearing Clearance: 0.00150 inch
Bearing Clearance Variance: 0.00060 - 0.00210 inch

702/3 measured clearance:
Nominal Rod Bearing Clearance: 0.00150 inch
Bearing Clearance Variance: 0.00115 - 0.00200 inch

What does a tad more open mean? Is that a technical term or your opinion again?

Source: http://wiki.rcollins.org/core/index....ring_Clearance


Edit:
Here is some more spoon fed info:
ACL-H-STD
Nominal Rod Bearing Clearance: 0.00190 inch
Bearing Clearance Variance: 0.00160 - 0.00235 inch

ACL-HX-STD
Nominal Rod Bearing Clearance: 0.00290 inch
Bearing Clearance Variance: 0.00240 - 0.00330 inch

VAC Clevite Bearings
Nominal Rod Bearing Clearance: 0.00210 inch
Bearing Clearance Variance: 0.00160 - 0.00220 inch

BE Bearings:
Nominal Rod Bearing Clearance: 0.00235 inch
Bearing Clearance Variance : 0.00180 - 0.00280 inch
*BE Bearings are the only ones measured and binned to have a better chance at achieving closest to target clearance, otherwise you can be on either end of those measurements.

[Scharbag]

This is all about probabilities.

There is the probability that an S65B40 was built with small journals, large rod big-ends and thin bearing shells. If we know the production statistics of all of the components, we can calculate the probability that the assembled engine will have a given clearance if randomly assembled. It seems reasonable to assume random assembly as, given that some S65B40s have failed with very few miles on the ODO, BMW did NOT seem to select components specific to the crank and rods with the S65. I wish they had...

It has been 20+ years since my brain was forced to do those calculations, so I will leave those details to people smarter, and more dedicated, than myself.

Assuming your engine was lucky enough to be built loose, the bearing clearance could actually be close to the nominal recommended by professional engine builders. If that is the case, winner winner chicken dinner!!

The above is not opinion. The above is simple math. And the simple fact remains: If you replace the bearings with OEM BMW, there exists the chance that the new 702/703 shells you install will be thicker (resulting in LESS clearance) than the 088/089 shells that you removed. Statistically speaking, if your 088/089 bearings are at the minimum thickness side of the distribution, you are guaranteed to be putting in thicker bearings if you use new BMW 702/703 bearings given the data that we currently have (see above).

It is your choice on what you do. Just make that choice based on data, not opinion.

Here is some data for your viewing pleasure (from RColins):

For the factory S65, going by the data gathered by BE, the "/" values are:

088/089 min = 0.00029"/" (YIKES - this is TOIGHT)
088/089 nominal = 0.00073"/"
088/089 max = 0.00103"/" (even if the stars align, barely meets best practice)

702/703 min = 0.00056"/"
702/703 nominal = 0.00073"/"
702/703 max = 0.00098"/"

BE Bearings (variance is due to crank and rod variance):

min = 0.00088"/" (minimum is still better than factory nominal)
nominal = 0.00115"/" (spot on what Clevite recommends for high revving engines)
max = 0.00137"/" (a little loose but still acceptable)

Other data can be found on the Wiki referenced in the post above.

Also, be sure you consider that Al/Tn (702/703) bearings are much harder than Pb/Cu (088/089 or BE) bearings, reducing their ability to deal with embedment of foreign particulates in your oil.

OP, if you do pull your bearings, I would love to see how they look!! Please post some photos.

Cheers,

[elvism]

170,000 miles on original bearings?? That's great Lol!!! Where are all those guys that were screaming change the bearings ASAP.No way they pass 100,000 miles

[tdott]

Originally Posted by elvism

170,000 miles on original bearings?? That's great Lol!!! Where are all those guys that were screaming change the bearings ASAP.No way they pass 100,000 miles

Every motor is different, unless you know which end of the tolerance stack you are on, there is no way to tell where or when it will blow.

So you either pray you are lucky, or mitigate the risk of having to replace a motor by doing the rb.
Many prefer to spend ~2k now versus $10-15k in the future.

[8500RPM]

Originally Posted by tdott

Every motor is different, unless you know which end of the tolerance stack you are on, there is no way to tell where or when it will blow.

So you either pray you are lucky, or mitigate the risk of having to replace a motor by doing the rb.
Many prefer to spend ~2k now versus $10-15k in the future.

Well said brother, I sleep easier now thanks to you and BE haha

[bmwpower603]

Originally Posted by Siajoon

If your car is running fine then the chance of your crank being fine is very high.. I'm not sure why they told you that.

Just swap out your bearings and you should be good to go!

It drives fine.

But if the throttle is abruptly engaged fully at low RPM the car misfires / sputters / hesitates. Then winds right up once it gets passed 2500 RPM. And I am unable to blip the throttle due to this...

I’m a little worried. But no engine codes at all... If it was plugs , and /or coils. Wouldn’t a code come up on ISTA??

Could this be something serious And related to the rotating assembly, or rod bearings? I do not have any sort of knock. Not even on cold starts.

[Siajoon]

Originally Posted by bmwpower603

It drives fine.

But if the throttle is abruptly engaged fully at low RPM the car misfires / sputters / hesitates. Then winds right up once it gets passed 2500 RPM. And I am unable to blip the throttle due to this...

I’m a little worried. But no engine codes at all... If it was plugs , and /or coils. Wouldn’t a code come up on ISTA??

Could this be something serious And related to the rotating assembly, or rod bearings? I do not have any sort of knock. Not even on cold starts.

I would start by changing your spark plugs, as mentioned around this forum this motor is very sensitive to old or dirty spark plugs.

[bmwpower603]

Originally Posted by Siajoon

I would start by changing your spark plugs, as mentioned around this forum this motor is very sensitive to old or dirty spark plugs.

I realize the spark plugs are used for knock detection/ignition advance adaptation on the engine. If they are old, the engine won't detect knock and over-advance the ignition cruising and this washes the rod bearings out..

Not sure why ISTA wouldn’t throw a code though.

I have appointment for rod bearing replacement on June 5th. The bmw shop is using BE bearings, and ARP bolts as people on here advised me to do. I will report back once I have more updates.

[pbonsalb]

I doubt your driveability issues have anything to do with the rod bearings. But many, myself included, think it is a good idea to change them as preventative maintenance on any used M3. Obviously, BMW disagrees. And to be fair, probably 90% of M3 are driving today on original rod bearings. Yet at the same time, 90% of those that come out look excessively worn. Your roll of the dice. Rod bearings with labor are about $2k. A used engine swap might be $12k. A rebuilt engine swap might be $15-20k.

I’d start with plugs. Maybe coils after that. Maybe send the fuel injectors out for cleaning and balancing after that. Maybe front 02. Best not to throw money at parts. Since you have all records, get them printed
out and study what has been done.

[randrews15]

Originally Posted by bmwpower603

I realize the spark plugs are used for knock detection/ignition advance adaptation on the engine. If they are old, the engine won't detect knock and over-advance the ignition cruising and this washes the rod bearings out..

Not sure why ISTA wouldn’t throw a code though.

I have appointment for rod bearing replacement on June 5th. The bmw shop is using BE bearings, and ARP bolts as people on here advised me to do. I will report back once I have more updates.

As with any used car purchase, give it some TLC and a full workup of preventive maintenance. Like the others have said, plugs, coils, air filter, and any other serviceable items should be addressed. Also, look at what type of gas you use. I exclusively use Shell in all my BMWs as I have found it's less apt to damage the emissions pump. Cheap gas burns less efficiently and can leave deposits behind. Every little thing adds up to keeping your car running top notch. Just my two cents...

I'm curious to see what the rod bearings look like after 170k.

[Mvy]

Plugs and coils go bad and sometimes dont throw codes. Id suspect thats your explanation as to why the car stutters at low rpm.

[drrust]

First off, I suspect you have this car:

WingZeroX5's Maintenance Log https://www.m3post.com/forums/showthread.php?t=1410659

Seems the PO did a lot of work.

I would be interested in the exact statement from Turner. Was it more if there is scoring the crank will need replacing? The idea of a leak down test isn't a bad one considering the mileage. That would be an added data point to assess the strength of the motor. I suspect Turner has considerable experience with S65s, but it seems the may deal with high budget racers and may approach issues differently. Sure one could put a stroker in to replace your motor! Who cares if it is more than twice what you paid for the car!

Not too long ago it was hard to find shops that would consider replacing the bearings. So at least you found some near you.

There is also a shop in Maine across from Portsmouth that rebuilds motors. He posts quite often and may be another place to consider. Shop is Fast Attack Motorsports, goes by jcolley on the forum.

[330ciprem]

Originally Posted by drrust

First off, I suspect you have this car

WingZeroX5's Maintenance Log https://www.m3post.com/forums/showthread.php?t=1410659

Different transmissions.

[drrust]

Originally Posted by 330ciprem

Different transmissions.

Thanks didn't catch that.

[smyles]

Originally Posted by bmwpower603

...Any advice would be appreciated.

Here's my advice: enjoy the car.

The RB craze only lives due to a) vendors, who profit from this craze, and b) folks who gave $$$ to vendors and have to justify the expense.
It's like a support group, they cannot act or admit otherwise.

[RedScytheM3]

Originally Posted by smyles

Here's my advice: enjoy the car.

The RB craze only lives due to a) vendors, who profit from this craze, and b) folks who gave $$$ to vendors and have to justify the expense.
It's like a support group, they cannot act or admit otherwise.

Gtfo here lol

[pbonsalb]

Originally Posted by smyles

Here's my advice: enjoy the car.

The RB craze only lives due to a) vendors, who profit from this craze, and b) folks who gave $$$ to vendors and have to justify the expense.
It's like a support group, they cannot act or admit otherwise.

Obviously you have not seen any bearings removed from these motors or know of the hundreds of engine failures. There is a definite risk. You have decided it is minimal and chosen to self-insure, which is fine since you could afford a $15k engine job. As with most insurances, the risk is small, but if it is something that concerns you, there are things you can do to reduce the risk. To say there is no risk is ignorant. To say there is no risk worth insuring against is opinion and opinions vary.

[tdott]

Originally Posted by smyles

Here's my advice: enjoy the car.

The RB craze only lives due to a) vendors, who profit from this craze, and b) folks who gave $$$ to vendors and have to justify the expense.
It's like a support group, they cannot act or admit otherwise.

Sounds like advice from an uneducated forum poster.

Those who understand the problem and the risk, don't need your advice. Goodluck with your German lottery ticket.

[bmwpower603]

Originally Posted by randrews15

As with any used car purchase, give it some TLC and a full workup of preventive maintenance. Like the others have said, plugs, coils, air filter, and any other serviceable items should be addressed. Also, look at what type of gas you use. I exclusively use Shell in all my BMWs as I have found it's less apt to damage the emissions pump. Cheap gas burns less efficiently and can leave deposits behind. Every little thing adds up to keeping your car running top notch. Just my two cents...

I'm curious to see what the rod bearings look like after 170k.

I’ve scheduled an appointment for June 5th. I will make sure and post pictures of the shells.. (The car currently doesn’t have knock) even on cold starts, and when warmed up.

I’m Deff nervous... I really can’t afford a rebuild. Having second thoughts for sure about this... I already paid for the bearings and bolts...

[SoCalRPM]

I'm beating a dead horse here as everyone else has already given you sound advice:

Find a different shop (not the dealer)

Get the bearings changed ASAP

Nothing you can do, or know, about the crank until you open it up. Hopefully it's okay but cross your fingers anyway.

Just do the preventative maintenance and hope for the best.

Enjoy it!

[bmwpower603]

Originally Posted by SoCalRPM

I'm beating a dead horse here as everyone else has already given you sound advice:

Find a different shop (not the dealer)

Get the bearings changed ASAP

Nothing you can do, or know, about the crank until you open it up. Hopefully it's okay but cross your fingers anyway.

Just do the preventative maintenance and hope for the best.

Enjoy it!

I realize I could be opening up a can of worms. The shop is doing it with the ARP studs, and BE bearings for $2900. .

Hopefully a new crank+ installation won’t be much more than 10g.. WORST case

I’m banking on everything being fine. Since there’s no knock. But I’ve heard there’s still a chance of crank scoring with no knock.

[s14_kev]

Originally Posted by bmwpower603

I realize I could be opening up a can of worms. The shop is doing it with the ARP studs, and BE bearings for $2900. .

Hopefully a new crank+ installation won’t be much more than 10g.. WORST case

I’m banking on everything being fine. Since there’s no knock. But I’ve heard there’s still a chance of crank scoring with no knock.

I would ask them if they can replace the motor mounts for free (just supply the parts). There is literally 5 minutes of work to do this at the same time.

Price seems ok as I am not too familiar with the shops in New Hampshire. Seems like everyone and their mom is doing them here in CA for $2,000 or less. Lowest I've seen is $1,750 in SoCal. Good luck, let us know how your crank looks! And we would love to see pics of these 170k mile bearings when they are pulled. BE + ARP is probably the best option.