S65 Engine Main Bearing Service, Documented

[charliev68]

Originally Posted by jvictormp

You're right. Let the engine die someday, we don't like it anyway.

No. You don’t get it! You have to pull the motor do the job right. You should definitely do the refresh after 100k miles. Trust me…I know!

[jvictormp]

Originally Posted by charliev68

No. You don’t get it! You have to pull the motor do the job right. You should definitely do the refresh after 100k miles. Trust me…I know!

There's no problem for me to remove the engine. Possibly engine in car, I said.

But, from what I understood, you're going to spend in parts, the value of a donor engine.

If it was just the main bearings cost, I'd definitely do it at home. Is it? Why is the "complete" refresh needed for a 50k miles engine? What if I decide to do it at home (either removing the engine or not) now (my engine is 50k miles) and again after more 50k miles? That's what I'm looking after.

[Glacial Pace]

Main bearing replacement without removing the engine sounds....... Interesting.
I assume that if they are doing that then they aren't removing the pistons and rods, just taking the bed plate off. Not sure how possible it will be to get it all properly sealed up after that.

I think if I was going to have the job done I would want to do the full engine rebuild, but if the cost is significantly less then I guess maybe it's worth doing.

I'll be tackling the rod bearings replacement job at home next weekend. I do not fancy attempting the main bearing job, at least not with the setup I currently have available to me.

[ab987]

Originally Posted by Glacial Pace

I guess there are a lot more crashed cars with usable engine blocks than there are cars with spun main bearings so getting a new block isn't an issue for now.

I wonder if these things might start to really climb in price as the number of donor cars reduces.

Seems like it's still very possible to get brand new blocks too - about $7000 including a full set of pistons too. You could reasonably have a fresh S65 for $10k in parts. Wish I knew that before spending $22k on a Carbahn engine...

[SYT_Shadow]

Originally Posted by jvictormp

SYT_Shadow

You're the one who made it possible for us to change RBs at home.

Now we need you to enlighten us with a video tutorial of dean's procedure and possibly with engine in car.

Let's make these engines last forever!

I'd love to, but a video would be 15h long and so hard to edit. I prefer to take my car to deansbimmer for a main bearing service when it gets to 150k

Main bearings aren't something I'm worried about

[Assimilator1]

Originally Posted by deansbimmer

It has been around 6 years after my original post. We continue to see a relatively steady number of main bearing failures, however still much lower than rod bearing failures. The below image of S65 blocks are from 2024 failures so far. We get engines in from all over as an S65 specialist. What we see in quantity is not typical of every shop.

Due to a recent video from an Australian company breathing new hysteria into the main bearing concern, I want to touch again on my opinion regarding main bearing replacements.

Main bearings are a relatively low risk. As these engines are ageing and accruing significant mileages across the sample pool, we will see more continue to fail simply as a matter of time.

Most of these cars are well past 100k miles now. As my original post demonstrates, a proper main bearing replacement service is quite intensive, and very costly if performed to this degree of quality. To consider this amount of disassembly and NOT carry out a full rebuild seems financially foolish.

Since we see mains fail at a low % and usually past 100k miles where the rest of the engine is tired also, we recommend to not worry about main bearings until you're ready to consider an engine rebuild.

Are you able to give us a little more info on each of those engines we see? (so I can add them to our blown engines list).
Would be after mileage, year, which state (I assume all from the US??).

Also curious like Glacial Pace on whether they all have no1 mains failure?

Originally Posted by jvictormp

what about that?

I wondered about something like that, but is their even room to do that?
Also, I'm sure their are other twin chain V8s out there, do they suffer the (presumed) no1 mains failure? If not, the answer could be something else.

[charliev68]

Originally Posted by ab987

Seems like it's still very possible to get brand new blocks too - about $7000 including a full set of pistons too. You could reasonably have a fresh S65 for $10k in parts. Wish I knew that before spending $22k on a Carbahn engine...

I see the part# for this is 11-11-0-036-844 and retails for around 8k but I highly doubt that it’s actually available. ECS states it as “no longer available” and most sites say “not in stock”. If you can really order a brand new block and pistons for 7-8k, no one would be buying used engines for around the same price.

[spammysammich]

I always thought they were NLA. I never found new stock and it has been years since I’ve heard of anyone getting a new short block from Germany.

[Partee Racing LLC]

Just found this, and as someone who now does this full time, I can say this is the most accurate and comprehensive thread on the topic I have seen! Spectacular job.

--Peter

PS: I should note that the No. 1 main bearing problem does seem to be relatively widespread. There are lots of theories, and I have mine, but there is really only one solution: more clearance on the No. 1 main bearing than the others. Most other BMW engines, such as the S62, show between .0005" and .001" additional clearance on the first main bearing not because of the chain, but because of the expansion of the crankshaft caused by the torquing of the harmonic balancer bolts. BMW specs maximum clearance of .002". On main number 1, I have gone as high as .003" and used .0025" on the remainder.

[Assimilator1]

Originally Posted by Partee Racing LLC

.....

--Peter

PS: I should note that the No. 1 main bearing problem does seem to be relatively widespread. There are lots of theories, and I have mine, but there is really only one solution: more clearance on the No. 1 main bearing than the others. Most other BMW engines, such as the S62, show between .0005" and .001" additional clearance on the first main bearing not because of the chain, but because of the expansion of the crankshaft caused by the torquing of the harmonic balancer bolts. BMW specs maximum clearance of .002". On main number 1, I have gone as high as .003" and used .0025" on the remainder.

Hmm, I guess this is a description issue (as I assume you know your stuff ), but I don't understand what you mean by "caused by the torquing of the harmonic balancer bolts", and I'm talking as a (UK) mechanic of many years.
By harmonic balancer do you actually mean the vibration damper as seen here?
By torquing, that normally means the force required to tighten a bolt etc to the correct force (at least in the UK). Presumably it's not that because either they'd work lose (they don't as far as I've heard), or nothing would happen to the bolts, for if their was a tightening force applied to them by changes in engine speed, it wouldn't be enough to keep tightening the bolts.
So by torquing, do you mean twisting them along their length? (although again, I can't see how. Surely that could only happen if their was insufficient clamping force? In which case, surely they'd work lose?).

Anyway, I'm puzzled , I look forwards to your explanation .

[Partee Racing LLC]

Sorry for being obtuse! All I mean is that when the balancer (harmonic balancer=vibration damper) bolts are installed, the No. 1 main bore expands, decreasing the bearing clearance. So if clearance is measured before the balancer is installed, you need about .0005" more clearance than if measured after the balancer is installed. If you are starting out with inadequate clearance by traditional engine building standards, as is the case with the S65, the situation is exacerbated.

--Peter

[Assimilator1]

Originally Posted by Partee Racing LLC

Sorry for being obtuse! All I mean is that when the balancer (harmonic balancer=vibration damper) bolts are installed, the No. 1 main bore expands, decreasing the bearing clearance. So if clearance is measured before the balancer is installed, you need about .0005" more clearance than if measured after the balancer is installed. If you are starting out with inadequate clearance by traditional engine building standards, as is the case with the S65, the situation is exacerbated.

--Peter

Got ya now , and interesting!

[BimmerRob08]

I got a question. Althogh it’s pretty clear from some videos of the upper no.1 main bearing is wearing faster due to the up-load of the front of the crank due to the dual chains pulling on it from the tension. That part seems to be very plausible from the wear. But increasing the tolerance to allow more oil flow may help with lubrication but does that not also allow slight more bounce or flexing of the shaft? I’m sure minute difference but the front of the crank shaft is putting unequal about of pressure as it spins in the no.1 bearing area.

Has anytime that rebult and replaced the no.1 bearing with larger clearance seen any engine failures later? In other words; does this remedy fix the problem? Almost seems impossible to get 200K + miles with out major overhaul, etc.

[spammysammich]

I don’t think of increasing clearance as allowing more flex of the crank. I look at it as reducing the likelihood of the crank from grabbing the bearing. Perhaps I’m incorrect in my understanding of how much the crank can flex.

[BimmerRob08]

Originally Posted by spammysammich

I don’t think of increasing clearance as allowing more flex of the crank. I look at it as reducing the likelihood of the crank from grabbing the bearing. Perhaps I’m incorrect in my understanding of how much the crank can flex.

Interesting observation. I wish some automotive engineers could way in on this crank issue.

[Assimilator1]

I'm not an AE (just a car mechanic/tech).
But I would've thought that increasing No1 mains clearance would at best make no difference to bearing wear due to the chains tension, to at worst increasing wear (very slightly) as the oil film between the pressure/loaded side of the crank and bearing will be very slightly shorter and so (slightly) higher pressure/load on the oil film.

Would be interesting to hear what deansbimmer and other engine builders thoughts are on this.

Another point that most people seem to miss, twin timing chains used to be quite common in BMW engines (& others I'm sure), before they started penny pinching.
I don't recall their being problems with their no1 mains? Unless I just haven't stumbled across it?
2 examples of BM engines with twin chains are the S62 (e39 M5) & M57 (3 ltr I6 diesel).

[Brandoch]

Originally Posted by Assimilator1

I'm not an AE (just a car mechanic/tech).
But I would've thought that increasing No1 mains clearance would at best make no difference to bearing wear due to the chains tension, to at worst increasing wear (very slightly) as the oil film between the pressure/loaded side of the crank and bearing will be very slightly shorter and so (slightly) higher pressure/load on the oil film.

Would be interesting to hear what deansbimmer and other engine builders thoughts are on this.

Another point that most people seem to miss, twin timing chains used to be quite common in BMW engines (& others I'm sure), before they started penny pinching.
I don't recall their being problems with their no1 mains? Unless I just haven't stumbled across it?
2 examples of BM engines with twin chains are the S62 (e39 M5) & M57 (3 ltr I6 diesel).

It may be because of the super long snout being unsupported. 2 double roller chains plus oil pump plus the harmonic balancer mounting holes/front oil seal area. I don't know if the newer lower engine pressure vanos creates more load on the timing system then the older high pressure vanos.

[RocketyMan]

Originally Posted by Brandoch

It may be because of the super long snout being unsupported. 2 double roller chains plus oil pump plus the harmonic balancer mounting holes/front oil seal area. I don't know if the newer lower engine pressure vanos creates more load on the timing system then the older high pressure vanos.

Yup. This!

[Assimilator1]

Longer snout than the S62?

[Brandoch]

Originally Posted by Assimilator1

Longer snout than the S62?

Single double row chain vs 2 double row chains.

[jvictormp]

Have you guys heard of something about start stop system causing the pressure to drop when stopped, then when starting engine, letting the crank touch the main bearings?

[bigjae1976]

Originally Posted by jvictormp

Have you guys heard of something about start stop system causing the pressure to drop when stopped, then when starting engine, letting the crank touch the main bearings?

I don't know...have you ever used the start/stop? It doesn't work half the time and then you just cook in the car in the summers at red lights. Then it scares the shit out of people because our cars aren't the quietest.

I don't think most people bother and many don't know the car has it. I also think it's kind of ridiculous considering you had the pay the gas guzzler tax when it was new so who the hell is driving an M3 and is worried about saving fuel.