Rod Bearings Inspection

[charliev68]

Bought a used engine with about 150k miles. Doing basic maintenance and improvements ie. WP, Spark Plugs, VANOS Cups, etc.
Decided to inspect the Rod Bearings to make sure. It has ACL Hx with ARP 625. Looks good…Should I replace them or just ride with them?

[a5m]

If you're that deep I'd just replace em with BE. They are the HX extra clearance ones and do look fine to my untrained eye.

[Helmsman]

Being a ACL HX/ARP625 driver since july 2018 - with no knowledge about what it currently looks down below - I'm happy to see your photo. Any more on the other?

[charliev68]

Forgot to take a picture of the upper bearing. I already buttoned it back on. It looked pretty much the same.
The only thing I’m a little concerned with is the extra clearance and oil pressure concerns.

[Helmsman]

Originally Posted by charliev68

Forgot to take a picture of the upper bearing. I already buttoned it back on. It looked pretty much the same.
The only thing I’m a little concerned with is the extra clearance and oil pressure concerns.

Any knowledge about how many miles the ACL bearings has on it?

[charliev68]

The only info I have is that the engine was from Arizona, was in a e93, and had 155k miles. Seller didn’t even know that the RB & Bolts were even done.

[charliev68]

Originally Posted by Helmsman

Being a ACL HX/ARP625 driver since july 2018 - with no knowledge about what it currently looks down below - I'm happy to see your photo. Any more on the other?

Are you a little concerned with the looser tolerances messing up your Main Bearing oiling?

[charliev68]

I’ve had really good luck with my original engine running BMW Rod Bearings WPCed showing decent wear on my Mains at 130k miles. Thinking of changing this engine back to OEMs WPCed.

[RugbyBro]

If the engine is out already then for sure pull the bed plate and crank and do mains too

[Helmsman]

Originally Posted by charliev68

Are you a little concerned with the looser tolerances messing up your Main Bearing oiling?

Not really but maybe due to lack of understanding of a potential issue in combination with generally calm driving conditions. Next time I have the RBs replaced I do however plan to go tighter, such as Mahle.

[RocketyMan]

Looser/tighter...it's irrelevant. It's what specs are you using and aiming for the end result of clearance.
You can use the STD and/or HX in combination to get to the spec-clearance.

[F4rmost]

I believe Chrisyphus has recommended oil pump gears for higher clearance bearings. They have reported consistency of main bearing failure with high clearance bearings and no gears.

[charliev68]

Originally Posted by Helmsman

Being a ACL HX/ARP625 driver since july 2018 - with no knowledge about what it currently looks down below - I'm happy to see your photo. Any more on the other?

Decided just to replace them for peace of mind.
Left side is rod side. Right side is cap side. ACL HX top and bottom.
Don’t know when the previous owner of the engine replaced the bearings but engine had 155k miles.

[former 240 s14]

Couple of recommendations from a guy who is knee deep in a rebuild after a total catastrophic engine loss.

1. Do the main bearings NOW. The engine is out and it is JUST as important as the ROD bearings. If number 1 main bearing spins you nuke the rest of your engine as the oil passage hole on the crank gets blocked.
2. As someone else said, do the SRD gears for sale from Rogue. $400 is good ensurance to bump up your oil pumps performance.

Good luck with the rebuild!

Rubin

[charliev68]

Rubin,
Can I get some pics of your MBs and the mileage of them removed?

[former 240 s14]

I don't have pics of the full set, but here is a snapshot of the spun #1 bearing and what the journal looked like after.

The engine had just been rebuilt for $20k (although poorly) 14k miles before it's death.

Rubin

[charliev68]

Yikes! What caused that? Apparently not age and mileage!

[RocketyMan]

Originally Posted by former 240 s14

I don't have pics of the full set, but here is a snapshot of the spun #1 bearing and what the journal looked like after.

The engine had just been rebuilt for $20k (although poorly) 14k miles before it's death.

Rubin

Dangit!
Notice tho the crack at the #1 oil feed hole. I've seen this countless times on failed main bearings.
$20k for a rebuild you say? Did that include labor R&R of the engine/powertrain into the vehicle?

[former 240 s14]

Originally Posted by charliev68

Yikes! What caused that? Apparently not age and mileage!

A few different things led to its demise. I have a thread about it here: https://www.m3post.com/forums/showthread.php?t=2210858 .

Cliffnotes:

1. Poor quality rebuild
2. Oil Starvation under high G braking and turns
3. Design of crank and double chains
4. Oil Pump design flaw for track use

Rubin

[charliev68]

Trust me…I know about MBs and rebuilding an S65 and what it involves.
At 150k I believe it is not necessary. Main bearings don’t wear down as aggressively as rod bearings.
I believe main bearing #1s are spinning because people are using too loose of a clearance in their rod bearings!
This is just my hypothesis after personally tearing down and rebuilding the s65.
This other engine is just my spare engine. I don’t think it’s necessary to replace the MBs.

[spammysammich]

Originally Posted by RocketyMan

Dangit!
Notice tho the crack at the #1 oil feed hole. I've seen this countless times on failed main bearings.
$20k for a rebuild you say? Did that include labor R&R of the engine/powertrain into the vehicle?

My buddy paid around 20k for a 4.2 from Carbahn not including what he paid to source a core. Then we almost set it on fire with a bad choice with the starter cabling 🙈

[former 240 s14]

Originally Posted by RocketyMan

Dangit!
Notice tho the crack at the #1 oil feed hole. I've seen this countless times on failed main bearings.
$20k for a rebuild you say? Did that include labor R&R of the engine/powertrain into the vehicle?

Yes, it was to pull the enigne, new block, built heads (minus cams), and all new gaskets seals etc.

The previous builder didn't even measure bearing clearance, his excause was "it's not a race engine." Sad thing is this guy has a relatively good reputation but karma is finally catching up it sounds like.

Rubin