s54 rod vs main bearings

[PDJ]

Too many variables to say one thing or even two things can save the bearings, a few things can shorten the time expectancy of the rod bearings

Too much load when cold, wrong oil, poor servicing, the list goes on

When BMW designed the S54 they made the rod bearings narrower and the bore wider, think of it as a drawing pin.

They also designed a poor diff for the Z4M as the left hand side output shaft is not nearly long enough have a look at one in bits and you will see what I mean

The cup holders where designed by an engineer that has now only just passed out of Uni as he designed them when in pre school.

The location of the roof motor was desided when there was a beer festival on with free beer and only 15 mins to come up with an answer as to where it was to go.

Other than that good cars

[Rombbb]

I wasn't going to respond to this, as there seems to be one of these every year or so.. but

Its not the amount of track days, or how high rpm you run, bearing shells cop it when the engine/oil isn't warmed up to spec and then given a hard time. no idea if swapping out oils early makes a difference, but i swap mine after every 3 or 4 depending on how long between track days. (thats probably too much as most of the guys at my track do every 5)

Best insurance you can do is just warm up your car properly before giving it the puhjesus, and as importantly, a proper cool down.
Shells should last up to 200k, but probably should be looked at around 100, as it is a consumable.

My question had a little variation, not when to replace rod bearings, but rod vs main.

Was wondering why mains are never mentioned, didn't knew they were under lesser stress.

[Rombbb]

drawing pin

Agree on the cup holder, roof don't know (have coupe), but bearings were intentional to reduce friction and increase responsiveness (I heard) and that shaft should be ok right, I mean, never heard those failing, they either reach their mounting spots or not/barely and break.

[R60BBA]

I've had mine since 2008 and 9,300 miles, so I know how it's been maintained. During the AUC/Insured Warranty period (up to 100,000 miles) it was serviced to schedule by BMW plus interim services myself, with an oil change about twice a quarter (I was doing 2,000 miles a month).

I've always believed in a proper warm up, and something that was instilled in me during my e34 M5 ownership, where valve clearances were every 10,000 miles.

It wasn't unexpected, and an overhaul was planned as a winter project, but it just happened on the last trip to the Ring that year (just after my mate drove it).

When we got it back, we thought it was just going to be a simple job as we'd stopped the engine the moment we heard the slight unevenness after a lunch break (it was fine when we were driving around the area, and before we stopped) - we only noticed it when I restarted after filling up. We took the filter out and it was covered in metal, we then took the filter apart and the inside was almost as bad. Took the cam cover off and it was like a glitter party in there.

So., we decided at a minimum it would be a top & bottom strip down anyway to see what everything was like, but as we found metal particles EVERYWHERE we decided if we did do a rebuild we'd do some upgrades too.

But them my mechanic got seriously ill, so everything went on pause (which happened to be longer than either of us hoped or wished for), and we decided that we'd see if we could get a good engine (a Z4M S54, not a e46 S54) with all the ancillaries so we had spares, we'd go for that, as a swap would be much simpler for him than spending time stripping & upgrading - and less costly overall.

guess it comes down to luck of the draw, how many track days prior to it going bang?

30+ in 10 years (Oulton Park, Cadwell, Ring), but multiple oil services every year, plus basically an Inspection II every year, and fully warmed up before unleashing the right foot.


BTW, there was no great shock when it happened, and the refresh had been budgeted for. We've always had European breakdown recovery (ADAC Plus originally, until they refused to recover my broken down M5 to a local garage due to it being a Bank Holiday weekend and everything being shut) for the inevitable repatriation we'd need if we had a breakdown...the only sour note was having to pay £1500 to get it home after the breakdown company refused to repatriate the car AFTER WE'D LEFT IT WITH THEM IN GERMANY and come home in a hire car ourselves. Took 6 months and the Ombudsman, but we got refunded, and the breakdown company got a slap.

160,000 miles including track use on original bearings is good usage.

It's unfortunate that yours spun just before you were about to commit to the service.

Track guys on other forums change theirs every 25,000 miles, and I believe race teams change them after every season.

Out of interest, what oil did you run?

[mmm-five]

Out of interest, what oil did you run?

It was always one of those things on the schedule (but not until it was past 100,000 miles), but other things kept taking priority.

It was run on OE Castrol 10w60...and only ever Shell V-Power, Tesco Momentum or Aral Ultimate 102 at the Ring (or Super E5 for the drive home).

The 115bhp 146 JTD beast got the cheapest diesel I could find whenever it needed it (which was usually less than £1/litre in Germany). Even that got 5,000 mile oil changes.