Main Bearing Replacement Without Removing Engine - Best approach?

S65Hunter wrote

Yup, im in Dallas so its just about a 45min drive for me. They did my Vanos covers, great work over there.

It's 4 hours for me, but completely worth it. Rod Bearings, Vanos covers, Valve Covers. Transmission service is next on the list.

S65Hunter wrote

Not taking the advice of one of the best S65 wizards in existence is crazy..

Who said I'm not taking advice? I was asking for it.

In any case, Brintech and other shops have used this method on many motors and been successful, so while one individual may advise against it, that isn't to say it's not achievable with due care.

greyspoke wrote

I have an idea and I want people to tell me it's good...

I'm lucky that I'm within driving distance of Coulter and my M3 takes an annual trip there for some TLC.

Eyeroll.


Someone who doesn't even wrench on their car taking shots at DIYers asking for advice is the pot calling the kettle black is it not?

TassieBMW wrote

In any case, Brintech and other shops have used this method on many motors and been successful, so while one individual may advise against it, that isn't to say it's not achievable with due care.

They’ve done it on s65s or they’ve done it on various motors?
Having done it myself, I just don’t see it being successful. If it’s not leaking and running without problems, hat’s off! If they are adding only 2 hours to the job…that’s amazing! I did everything by the work shop manual and was still nervous if it would be okay.

charliev68 wrote

They’ve done it on s65s or they’ve done it on various motors?
Having done it myself, I just don’t see it being successful. If it’s not leaking and running without problems, hat’s off! If they are adding only 2 hours to the job…that’s amazing! I did everything by the work shop manual and was still nervous if it would be okay.

On S65's. They do it routinely as they have seen a lot of main failures come through their doors. I'm not sure if this is the exact method they're using but it must be, as they say they do it in car and I'm sure they wouldn't be going to the trouble of removing the trans and timing gear to get the crank out, as at that point an engine drop would be easier.

The only two parts of the job which concern me would be actually rolling the upper bearings out/in and seating them properly, and getting the seals not to leak. I've seen a lot of videos of people doing it in more agricultural engines with main caps, but not bed plate motors. In theory it should be no different though, but the tighter clearances would mean the potential for damage is greater. With the seals, I guess you could use some form of sealant to help them re-seal correctly (obviously not RTV or anything that could block an oiling hole). Worst case would be you'd need to pull the crank pulley and trans/flywheel to replace them if they leaked.

I’d still follow deansbimmer’s advice but I wonder — can you pull the crank out easier if you lock the cams and then take out the timing chain tensioner to get some extra slack? Still have to drop the trans but maybe slightly easier?

Again don’t think it’s worth it, just curious.

I personally would consider engine out rebuild preventatively once my car exceeds 150,000 miles and if I plan on keeping it for another 100,000 miles.
At over 150,000 miles I’m sure there are other parts that would benefit from overhauling, main bearings are the main concern over that mileage though.
Up until that mileage, I’d say take your chances. Of course I did my rod bearings at 75,000 miles.
Just my thoughts..

kolosy wrote

I’d still follow deansbimmer’s advice but I wonder — can you pull the crank out easier if you lock the cams and then take out the timing chain tensioner to get some extra slack? Still have to drop the trans but maybe slightly easier?

Again don’t think it’s worth it, just curious.

If you were to drop the crank out then yeah I'd imagine that's the easiest way to do it. The way I'm talking about though is leaving the crank in place and 'rolling in' the upper shells.

BimmerMan33 wrote

I personally would consider engine out rebuild preventatively once my car exceeds 150,000 miles and if I plan on keeping it for another 100,000 miles.
At over 150,000 miles I’m sure there are other parts that would benefit from overhauling, main bearings are the main concern over that mileage though.
Up until that mileage, I’d say take your chances. Of course I did my rod bearings at 75,000 miles.
Just my thoughts..

The scariest thing with main failures is I'd say there's a lot more out there than anyone will ever know about, and most people will chalk it up to rod bearings but never open up the engine to discover it was actually a main.

It would be great to get better insight into just how many S65's have met their end this way, but I suspect we'll never know.

I'm still on the fence about doing this and documenting it for the community, or doing RB's and leaving it at that, and crossing my fingers and toes that mains don't become an issue soon after or further down the track.

I've been continuing to look online and there seems to be zero info out there in terms of doing it in car, so those who have done it this way are clearly keeping the details close to their chest.

After looking into it a bit more, it seems a few other parts need to be detached to pull off the bedplate, namely the AC compressor, alternator, engine mount brackets and potentially one or two other incidental bolts holding on brackets, etc.

The parts of the job which make me nervous remain the sealing aspect; Impacting the integrity of the front and rear main seals and then having to replace them at a later date. Not a catastrophic issue but would be a real pain to do.
Also, injecting the sealant that goes between the bedplate and block could present an issue as there would be no access to apply the green primer liquid at the front and rear main seals once the sealant begins oozing out. A potential solution to this presented by AI was using a non-anaerobic sealant that does not need a lack of air to cure, unlike the stuff BMW used from factory.

If anyone else has some constructive input on this topic, please chime in.

In car may not be the 'right way' to do it, but if this lower barrier to entry method could save S65's that may otherwise end up as scrap metal, I think it's worth a shot.

TassieBMW wrote

As the incidence of failed upper #1 mains increases, more shops are coming up with solutions for replacement that don't require a full engine out and total disassembly.
This got me thinking about the process by which they're doing this, and makes me keen to give it a try myself on my 100k mile E90.

I can only see two viable methods of doing it. The first would be to remove the transmission and flywheel, de-tension the timing chains and remove the vanos adjusters, then drop the bedplate and crank together, which allows full access to upper and lower mains. Given the work required to do this, it seems like you'd not be gaining much (if anything) in terms of hours of labour and that dropping the engine would probably be an easier approach.

The second approach, and one that interests me most, is simply dropping the bedplate and 'rolling in' the upper mains without removing the crank. This is commonly done on engines with main caps, but not so much on bed plate motors, at least that I've seen. Theoretically though, I can't see why it isn't possible.

I can't find any documented in-car main replacements online, so I'm also keen to do a video or forum post on this (if it can be done) that others can follow as this issue continues to become a more discussed topic.

Keen to hear people's thoughts on this and from anyone who has attempted it themselves.

Your profile states you're driving a 330i M-Sport. Are your questions about in car main bearing replacement for an S65 V8 or a 6 cylinder 330i?

DrFerry wrote

Your profile states you're driving a 330i M-Sport. Are your questions about in car main bearing replacement for an S65 V8 or a 6 cylinder 330i?

I’m going to lose my shit if this entire time they were talking about an N5X engine lmao

Because there is no fucking way this shop is replacing that many main earrings on S65s and there’s NOT that many E9X M3s in Australia and if they are doing that many then the percentage of main bearing failures for S65s would be really high 😂

Yeah, you can manage this service without dropping the engine from the car. Don’t listen to what others imply.

The solution is fairly straightforward in theory: remove the car from around the engine instead.

DrFerry wrote

Your profile states you're driving a 330i M-Sport. Are your questions about in car main bearing replacement for an S65 V8 or a 6 cylinder 330i?

Haven't updated it but I have that car, plus an M6, plus an M3.

omgzirra_exe wrote

I’m going to lose my shit if this entire time they were talking about an N5X engine lmao

Because there is no fucking way this shop is replacing that many main earrings on S65s and there’s NOT that many E9X M3s in Australia and if they are doing that many then the percentage of main bearing failures for S65s would be really high 😂

That shop has done 25+ main bearing jobs this way, and there's more E9X M3's in Australia than a lot of you Americans probably realise.

Here's a photo of this service being carried out, provided by the shop owner.

e39Origin wrote

Yeah, you can manage this service without dropping the engine from the car. Don’t listen to what others imply.

The solution is fairly straightforward in theory: remove the car from around the engine instead.

See above, it's very much do-able.

Eww

TassieBMW wrote

See above, it's very much do-able.

Please ask the shop for the old main bearing shells. No offense but this seems like it might be some sort of scam. How can the upper main bearing shells be removed with the crank still in position? Just asking for an explanation of the removal method. I hope it all goes well for you and is legitimate.

DrFerry wrote

Please ask the shop for the old main bearing shells. No offense but this seems like it might be some sort of scam. How can the upper main bearing shells be removed with the crank still in position? Just asking for an explanation of the removal method. I hope it all goes well for you and is legitimate.

I mean I assume you push it at the edge so it rotates on the crank (like a spun bearing does). Possibly you rotate it with the crank also?

Doing a bottom end rebuild with out replacing the timing chain and guides, the front and rear main seals, not checking the main journals for cracks. Checking clearances with plasigauge is going to be a choir. The chances of FOD is a significant risk.

WTF absolutely ridiculous.

This is not a few hundred dollar civic engine from 2000.

People who do this should not work on other people's cars, and people who pay for this should not own a M3.

kolosy wrote

I mean I assume you push it at the edge so it rotates on the crank (like a spun bearing does). Possibly you rotate it with the crank also?

Don't think that would work because of the deep collars on the S65 main bearings. It's why I mentioned above for the O.P. to ask the shop for the 'old' main bearing shells...
https://www.m3post.com/forums/showthread.php?t=1504062
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