Holy Crap! The main bearing issue seems to be the cause of rod bearing failures

[Bmwdoubles_]

This video was just put out a few days ago showing several S65 engines at different mileages that locked up. They go on to demonstrate how the #1 main bearing puts a high load on the upper bearing causing a cascading bearing failure. The say the double chain has too much tension up front. They are looking into a fix for that but the discovery is too new so no proven solution as of yet.

They do have a fix for the #1 main bearing problem making a custom main bearing bored out to allow for more tolerance but holy shit that’s not for the faint of heart.

Some people in the comments mention what about using 10-40 oil and the the company replied not a bad idea and change every 3k.

My buddy just had his bearings done 30k ago with frequent oil changes and his locked up proving this video to be more truer than ever. He did find someone who can rebuild it for 8k but not sure if that includes removal and installation. A main bearing labor cost is gonna be at half that cost? So preventative main bearing cost could be worth it.

The guys in the video make a good point stating tight tolerance race engines get rebuilt after every race. We’re out here DDing in our race engines pushing are cars to the limit on the street and on track only changing the bearings.

So the question is how much is a main bearing replacement cost?

[charliev68]

It’s a thing! All performance engines have a half life. Refreshing is an inevitable reality.

[deansbimmer]

Yes.... It has been talked about here for years. Not really new information. Don't believe too much about the tech info in the video. It's not cost effective as a preventative service.

[Bmwdoubles_]

Originally Posted by deansbimmer

Yes.... It has been talked about here for years. Not really new information. Don't believe too much about the tech info in the video. It's not cost effective as a preventative service.

I saw a post from 2018 kinda of around this issue but not as detailed as that video. Those guys show pretty good proof the the number 1 upper bearing is taking a heavy load explaining that the S85 doesn’t see that due to a single chain as opposed to the S65’s double.

I appreciate what you and your team do. Can you elaborate a little more as to why this wouldn’t be the culprit or why this not a preventative maintenance item?

[M3SQRD]

Originally Posted by Bmwdoubles_

I saw a post from 2018 kinda of around this issue but not as detailed as that video. Those guys show pretty good proof the the number 1 upper bearing is taking a heavy load explaining that the S85 doesn’t see that due to a single chain as opposed to the S65’s double.

I appreciate what you and your team do. Can you elaborate a little more as to why this wouldn’t be the culprit or why this not a preventative maintenance item?

The MB issue has been a known issue for several years. Fortunately, the wear rate is much slower than the RB wear rate. MB #1 is the most abused. MB is not the primary cause of RB wear, it’s the tolerances of the RB that are the primary cause of RB wear.

It requires a costly engine-out job to correctly replace the MBs unlike the simpler engine-in preventative RB replacement. Once the engine’s out, it makes more sense at that point to do a full engine rebuild.

[omgzirra_exe]

Originally Posted by Bmwdoubles_

I saw a post from 2018 kinda of around this issue but not as detailed as that video. Those guys show pretty good proof the the number 1 upper bearing is taking a heavy load explaining that the S85 doesn’t see that due to a single chain as opposed to the S65’s double.

I appreciate what you and your team do. Can you elaborate a little more as to why this wouldn’t be the culprit or why this not a preventative maintenance item?

if you want to spend 15-20K for a engine out rebuild. you can. lol

people need to remember these are race engines. they wear out faster than a normal engine would, especially a high revving low displacement V8.

so yes, the main bearing is NOT a CHEAP preventative maintenance item.

[charliev68]

If one follows deansbimmer’s write up and you don’t separate the head and pistons I don’t see the parts being more than 2k. I guess labor is relative to the person or shop doing the work.

[Bmwdoubles_]

Originally Posted by charliev68

If one follows deansbimmer’s write up and you don’t separate the head and pistons I don’t see the parts being more than 2k. I guess labor is relative to the person or shop doing the work.

The same company responded. The repair in car 3800

[charliev68]

$3800 and “incar” LOL 😂!!! That’s like beach front property in Arizona for a discount. Anything is possible, but dropping the bed plate and crank upside down facing up would be like rolling shit uphill!

[deansbimmer]

Originally Posted by Bmwdoubles_

I saw a post from 2018 kinda of around this issue but not as detailed as that video. Those guys show pretty good proof the the number 1 upper bearing is taking a heavy load explaining that the S85 doesn’t see that due to a single chain as opposed to the S65’s double.

I appreciate what you and your team do. Can you elaborate a little more as to why this wouldn’t be the culprit or why this not a preventative maintenance item?

The S85 doesn't see the same kind of loading on the front bearing because the v10 has a longer crankshaft with a whole extra main journal for support. It's much more stable than the V8's shorter crank with one fewer supportive journals. It has little to do with a simplex vs duplex chain design or the strain the valvetrain places on the forward journal (all OHV engines have some degree of this strain applied to the front journal).

I can't fault a shop for their hunger to capture business, but a $3800 main bearing job will be rife with longevity concerns. I wouldn't touch that with a ten foot pole as an educated customer. As a shop owner, I wouldn't touch it from a liability standpoint either. I bill $2899 for a full service S65 rod bearing job. To add the further tasks for mains strikes me as insanity for anything less than double that. (assuming, academically speaking, in-car work).

Attempting mains in car, especially on a higher mileage is not a recipe for success. The cleanliness alone for such precision tasks is not conducive to such an environment.

Parts are not the main expense. The labor time and skill are the main cost. If a shop charges only $40 per hour then the low cost job explains a lot, but that leads to questions of the shop's establishment and qualifications.

Regarding parts costs and entertaining the notion of a down and dirty an in-car main bearing service, with rod bearing and rod bolt upgrades, seals, gaskets, cam timing consumables, engine mounts, etc., there should be roughly 30 part lines totaling roughly $3100 in parts alone (list prices). Given the wide range in quotes, this confirms that there is broad interpretation into what constitutes a main bearing job at an advertised price point.

Mains are not going to be a likely concern until the engine is near or past 100k miles. Off the top of my head I've only seen a couple of main failures on engines below 100k that weren't the result of poor maintenance.

For these reasons I recommend mains to only be considered among an engine-out rebuild where everything can be properly disassembled, cleaned, measured, etc.

[Bmwdoubles_]

Originally Posted by deansbimmer

The S85 doesn't see the same kind of loading on the front bearing because the v10 has a longer crankshaft with a whole extra main journal for support. It's much more stable than the V8's shorter crank with one fewer supportive journals. It has little to do with a simplex vs duplex chain design or the strain the valvetrain places on the forward journal (all OHV engines have some degree of this strain applied to the front journal).

I can't fault a shop for their hunger to capture business, but a $3800 main bearing job will be rife with longevity concerns. I wouldn't touch that with a ten foot pole as an educated customer. As a shop owner, I wouldn't touch it from a liability standpoint either. I bill $2899 for a full service S65 rod bearing job. To add the further tasks for mains strikes me as insanity for anything less than double that. (assuming, academically speaking, in-car work).

Attempting mains in car, especially on a higher mileage is not a recipe for success. The cleanliness alone for such precision tasks is not conducive to such an environment.

Parts are not the main expense. The labor time and skill are the main cost. If a shop charges only $40 per hour then the low cost job explains a lot, but that leads to questions of the shop's establishment and qualifications.

Regarding parts costs and entertaining the notion of a down and dirty an in-car main bearing service, with rod bearing and rod bolt upgrades, seals, gaskets, cam timing consumables, engine mounts, etc., there should be roughly 30 part lines totaling roughly $3100 in parts alone (list [...]

Makes sense thank you for that input.

[Soden82]

Being supercharged, seems like I should anticipate an engine out rebuild around 100k.

At that rate, I would upgrade the internals and go with a bigger supercharger to make it make sense.

[8Krpms]

Has anyone followed up on this supposed "engine in car" main bearing swap? Can it actually be done properly?

[spammysammich]

Not likely. If it is a clearance problem you need to thoroughly clean the crank and block to measure. This will be easiest with engine out. You might be able to leave the pistons/rods/heads alone while you measure the mains to save on a little bit of labor but you need to be extremely cautious and clean. This isn’t a case where you can guess at the clearance and just roll bearings in. I could be wrong. It would be nice.

[serranot]

Originally Posted by Soden82

Being supercharged, seems like I should anticipate an engine out rebuild around 100k.

At that rate, I would upgrade the internals and go with a bigger supercharger to make it make sense.

From what I have read, being supercharged puts additional stress on that bearing. It isn't so much the forced induction as it is the additional stress not he #1 main from the supercharger belt.