proper diagnostic process for RB?

[tweny]

I got a soft knock sound today after I drove the car really hard. it's an 11 and has 43k miles. I towed the car to the shop, but he's no expert in S65 engines. I just want to know if it's road bearings. I'm getting a lot of mixed input on what it might be.

EDIT: forgot to mention you can only hear the knock when I go over 2k rpm.

[pbonsalb]

If you are hearing rod knock from bad bearings, I think it’s too late.

[Siajoon]

Doesn't anyone do a little searching before creating a thread ?

[tweny]

Originally Posted by Siajoon

Doesn't anyone do a little searching before creating a thread ?

i did. i've watched over 15 videos of ticking and knocking sounds and none of them sounded close to mine. most people said rod bearings, others said lifters, timing chain, coil, cog, etc. i wouldn't have created this post if i knew what it was. thank you for your input.

[pbonsalb]

M3 Belgium has listened to audio of a lot of cars. Record yours and send it to him.

The only real way to diagnose rod bearings is to inspect them. It’s about 8 hours of labor to inspect them. Might as well change them since it’s no additional labor.

[BeaterM3]

Originally Posted by tweny

I got a soft knock sound today after I drove the car really hard. it's an 11 and has 43k miles. I towed the car to the shop, but he's no expert in S65 engines. I just want to know if it's road bearings. I'm getting a lot of mixed input on what it might be.

EDIT: forgot to mention you can only hear the knock when I go over 2k rpm.

My month old to me M3 had a flawless oil analysis and the engine sounded totally healthy and the rod bearings were nearing catastrophic failure. In the top 3 worst the shop had seen.

So it is really a roll of the dice.

[Scharbag]

Originally Posted by tweny

I got a soft knock sound today after I drove the car really hard. it's an 11 and has 43k miles. I towed the car to the shop, but he's no expert in S65 engines. I just want to know if it's road bearings. I'm getting a lot of mixed input on what it might be.

EDIT: forgot to mention you can only hear the knock when I go over 2k rpm.

If you are the same Texan that recently posted a video on Facebook's E9X M3 V8 Owners club, then I would say it sounds like a rod bearing failure. I say this because it makes pronounced knock when increasing RPM but gets better when RPMs are dropping. This sounds similar to the few times I have spun bearings at the track.

An easy way to check is to remove your oil filter housing. If it is a spun bearing, there will be pronounced metal in the filter assembly. Check this first - make sure you remove the filter and have a good close look with a good shop light.

If there is no metal in your filter housing, then I would still be very careful and check if it is the AC compressor by removing the accessory belt and gently try to recreate the sound again (and ONLY if your oil is clean in the filter assembly - take a goooood hard look in there). If the sound is still there, it is a bearing. If there is no sound without the accessory belt, then put the belt back on. If the sound comes back, then it is likely your AC compressor.

Good luck sir. I feel your pain.

[sibhusz06]

you need to remove your serpentine belts and ensure the alternator and or another accessory isnt causing this.

[mapster37]

at this point is probably best to bring it to someone who knows these cars/engines. guessing can get very expensive....

[BayE30]

yer in TX, if yer close to DFW area, take it to Mporium BMW. They are one of the most reputable s65 shops in the USA.

[tweny]

got the bearings out, theyre toast. now I'll do some research on what the best rb/bolt combo is.

[bvrider1]

lets see them

[tweny]

will snap a better pic when I can.

[Helmsman]

Ouch, crank ok?

[tweny]

Originally Posted by Helmsman

Ouch, crank ok?

I wanted to ask if I can check the crank's condition, without taking the engine apart. is it visible from the bottom after the bearings are taken out?

[Helmsman]

Originally Posted by tweny

I wanted to ask if I can check the crank's condition, without taking the engine apart. is it visible from the bottom after the bearings are taken out?

I believe you can, at least get a good enough feel for whether worth while to try with new shells, but better see if one of the experienced engine folks chimes in here.

[Scharbag]

Originally Posted by tweny

I wanted to ask if I can check the crank's condition, without taking the engine apart. is it visible from the bottom after the bearings are taken out?

Tread carefully here. If I were you, I would make sure a good engine expert gives you the go-ahead before you throw bearings and bolts at it. As far as that goes, I would recommend bearings that ensure proper clearance, such as BE, VAC or ACL (personally I used BE). BE-ARP or OEM would be my bolt of choice, regardless of what bearings are being used.

Did a bearing actually spin and ruin a rod? Was there a lot of metal in the oil? If so, I have read that you will need to take the engine apart or you will likely have VANOS issues due to debris. Also, if there was a lot of metal or heat, your mains could be compromised. It would suck to blow the engine after changing the rod bearings because of main issues.

If a bearing did not spin and you do not have metal in the oil, then you got LUCKY!!

Good luck with the fix!!

[m235boy]

Aren't the 2011's aluminum bearings? Why does it look like they they have copper in them? Or is that just from the heat

[Dpc2u]

Originally Posted by dardapimp

Aren't the 2011's aluminum bearings? Why does it look like they they have copper in them? Or is that just from the heat

I was wondering the same thing. Looks like the older bearing.

[Scharbag]

Originally Posted by dardapimp

Aren't the 2011's aluminum bearings? Why does it look like they they have copper in them? Or is that just from the heat

My 2011 MY had 088/089 bearings in it. My production date was 04/29/2010. When exactly the 702/703 bearings were put in the engine is a bit of a mystery.

Cheers,

[pbonsalb]

You could post pictures of the crank journals and probably get someone like deansbimmer to comment. If they are not visibly scratched my guess is they are fine. With some searching here you can find pictures of crank journals, both ones in good shape and ones damaged by bad bearings. Against advice here, one guy recently replaced really bad bearings on a crank that most thought was damaged. The motor ran for about 2000 more miles before failing.

[BimmerRules!]

Originally Posted by revengeismine

My month old to me M3 had a flawless oil analysis and the engine sounded totally healthy and the rod bearings were nearing catastrophic failure. In the top 3 worst the shop had seen.

So it is really a roll of the dice.

Dang! sorry to read that. Hope you caught it and fixed it before bigger issues.

Bunch of queries pls:

Which year was your car? How many miles were on it? And how did you know - that too within a month - that the RB's were nearing failure?