Another Rod Bearing Story

[R60BBA]

You said that you changed yours, so you must believe the hype too.

Yeah I did, 4 years ago when I was new to M ownership.

My position has since changed and I don’t see it reverting.

An easy decision when made from a position of safety. I wonder if you’d feel the same driving a >100k mile car of unknown provenance running the original bearing shells…

Wouldn’t buy any car (let alone an M car) of unknown provenance…would you?

But I would happily buy something like a Z4M Coupe and would not be concerned about the shells as long as it had a clean service history and low owners.

I would only get them done imminently if I was seeking to track the car for peace of mind.

Life is too short to worry about things which have been blown out of proportion.

 

[beanie]

Whilst I’d agree that car forums often exaggerate the realities of these issues, to deny there’s a frequent problem seems like burying your head in the sand. I’d agree that the vanos issue is overstated on these but bearing wear is real and worth taking in to account imo.

Put it this way, whenever a new thread pops up about bearings, what do you expect to see inside, fresh/lightly worn shells or pictures of tired and copper coloured shells? I think I could count on one hand the amount of times bearings have come out and I’ve thought ‘they could go back in’

There’s also a lot to be said about peace of mind. Even if it is proportionally over-represented as an issue, if getting them done means you can truly relax and enjoy the car then it’s money well spent and cheap insurance in the long run.

 

[tomscott]

Your either one side or the other.

Its a silly argument really. There are so many factors and its down to personal preference on how you analyse risk. Being so adamant one way or the other doesn't make sense to me.

I would suggest being aware and being sensible about it is the best policy. Giving wild advice and scaremongering one way or the other doesn't help anyone, especially someone who is looking to get into a car so I would say bare it in mind.

At the end of the day finding a 1 or 2 owner car is rare now they are 15 years old. The S54 has been known for rod bearing issues since day dot, yes the variant in the Z is probably the best with the later bearings but it is a wear point.

The bottom line is that you can have a lot done at the same time to protect your investment for a relatively small amount of money.

Depends how you look at it. I would rather spend £1200 that £6k.

On the flip side.... Ive been a regular on this forum for 11 years and ive seen at most a dozen threads about cars throwing a bearing. Those cars have been used as intended, tracked and pushed hard. There were also the very unfortunate which I can think of 2, where someone has been unlucky and the engine went but the history of how the car was treated by previous owners was unknown.

Plus this is a forum you tend to find people with issues come to these places first to tell the world.

So even with the 1200 odd Z4Ms in the UK and roughly its still a tiny amount of cars (im not saying anything about concrete numbers). Plus there are a lot of European and American owners on here too so a much bigger pool.

Im not overly worried. I think a decent rule of thumb is 80-100k to have them changed. Mine is on 73 has had 2 owners, ive done 8k in 3 years so im going to aim at 80 but what ever service lands closest to that time.

These engines are still super impressive the fact that many of these engine have hit 150+ for a high performance engine is amazing yet they can do much more than that.

 

[flimper]

Tomscott, what other work should be done at the same time?

 

[PDJ]

The work that should be done at the same time is
Check replace the oil pressure relief valve plunger see picture above this if fails open will kill your engine as it dumps the oil back to sump and very little to the rest of the engine. I fitted an external one.

Oil pump drive chain and guides my guide was worn.

Then check replace everything that has to come off to get the sump pan off which is a lot if you do it at home, a garage can drop the whole front sub frame in one go but at home it is a bit at a time

Top tip if you do it your self

Strip it all down remove sump pan clean all the drips of oil off wrap sump in cling film to keep dirt out and do the bearing work a few days latter as oil dripping on your face is unpleasant

 

[BMWZ4MC]

Yeah I did, 4 years ago when I was new to M ownership.

My position has since changed and I don’t see it reverting.

An easy decision when made from a position of safety. I wonder if you’d feel the same driving a >100k mile car of unknown provenance running the original bearing shells…

Wouldn’t buy any car (let alone an M car) of unknown provenance…would you?…

How can a secondhand car be anything else unless it is known to you personally from the day of delivery?

 

[tomscott]

Tomscott, what other work should be done at the same time?

PJD knows more about this than me but other commons things to have done are engine and gearbox mounts replaced. I can feel my mounts are bad, when your on the motorway doing 60-70 hit the throttle and then take your foot off you can feel the drive train move excessively then they need doing. TBH the mounts are rubber and most will have failed by now because of age they squash and often split.

The above is an E92 but similar mount.

The mounting bolts for the cam sprockets. The original bolts are known for working themselves loose, which puts more stress on the the shank portion, and they have been known to snap straight off.

 

[GuidoK]

I’d agree that the vanos issue is overstated on these but bearing wear is real and worth taking in to account imo.

Both the breaking of a tab on the exhaust hub as well as those little bolts starting to shear are real problems.
I know of people who had both and are quite mellow drivers (not tracking their cars). So I don't think it's an abuse problem, it can just 'happen'.

 

[beanie]

Both the breaking of a tab on the exhaust hub as well as those little bolts starting to shear are real problems.
I know of people who had both and are quite mellow drivers (not tracking their cars). So I don't think it's an abuse problem, it can just 'happen'.

I know all about the issues and they, together with the engines ticks and taps, drove me crazy for a little while! I ended up getting the vanos overhauled and the pump disc replaced with the beisan part a few years back. At the time there was lots of talk about the issues and whilst I agree, it can happen, I put it somewhere between cam lobe wear and bearing wear as a potential risk.

I’d still say that, whilst potentially serious, it’s not particularly common, at least not as common as copper coloured bearings. All in my opinion, of course

 

[GuidoK]

it’s not particularly common, at least not as common as copper coloured bearings.

Of course it's not as common. The rodbearings wear. In every S54.
But, as far as internal engine problems go in general, still pretty common.

Cam lobe wear and cam followers wear is indeed also an issue (which is not surprising if you look at the insane cam lobe profiles the s54 has), but those should be caught when doing the periodic valve clearance adjustment.
And cam lobe wear doesn't really have the potential to seriously damage your engine, although replacing cams and followers is very expenisve, so not very nice if it's your engine that has that.
For people who are interested in replacing their oil pump regulator piston: https://burkhart-engineering.com/shop/bmw/bmw-ag/bmw-z3-z4-z8/dlc-edelstahlkolben-passend-fuer-s54-oelpumpe-z4-m-e46-m3-inkl-csl-bmw/

 

[BMWZ4MC]

Great information, thanks GuidoK
Premature cam lobe wear seems to be a direct consequence of follower wear. I know of several S54 cars that have had new cams and followers, including a couple of people who exchanged the worn OEM followers for new OEM followers and then had to replace those too when the case hardening failed. I've yet to hear of anyone who has encountered premature wear when they've fitted Schrick followers, but I accept that the sample size is pretty small! I suspect that a lack of oil supply to the head contributes to the problem in some instances, especially if the car is used hard without any mechanical sympathy.

 

[GuidoK]

I suspect that a lack of oil supply to the head contributes to the problem in some instances, especially if the car is used hard without any mechanical sympathy.

Yeah could be. Could also be a temperature problem. Most reports of worn cam follwers come from the US; lots of people track the cars there in intense desert heat. Maybe the head gets warmer there and the oil film of 10w60 is less effective there.

An oil pressure gage/sensor in the back of the head is a good mod if you track the car (I believe these engines only have an oil pressue switch so there's also no logging on oil pressure).

 

[Vanne]

There is logging of oil px,at least on mine there is.

 

[Polarbert]

I’d agree that the vanos issue is overstated on these but bearing wear is real and worth taking in to account imo.

Both the breaking of a tab on the exhaust hub as well as those little bolts starting to shear are real problems.
I know of people who had both and are quite mellow drivers (not tracking their cars). So I don't think it's an abuse problem, it can just 'happen'.

I can't remember if I stated in the original post but the tab on my exhaust hub had snapped. I've never tracked the car.

 

[GuidoK]

I can't remember if I stated in the original post but the tab on my exhaust hub had snapped. I've never tracked the car.

My opinion is that it's more common than most people think.
And it's becoming a very expensive BMW part, like so many parts from older models now. (dealerprice: €920,-- incl VAT).

Beisan and VAC motorsports both have a reinforced one (also still expenisve), and in the past there was a very nice version from "turbo toy" (I think a user on m3cutters), that had tabs made from C300 steel (a maraging steel), which is a very expensive and exotic steel (mainly used in aircraft landing carriages, so suitable for extreme forces). But that last one isn't being made anymore I think.

There is logging of oil px,at least on mine there is.

But then you have either an aftermarket ecu with extra sensor, or auxillary monitoring/logging equipment :wink:
What kind of oil pressure do you get when your engine is hot? (at low revs and at high revs?)

 

[PDJ]

What kind of oil pressure do you get when your engine is hot? (at low revs and at high revs?)


I my car from the oil pressure gauge i get between 15 and 20psi when hot at tick over and 55 to 60psi at revs over 4000rpm when hot

The pressure on a cold start up can be as high as 120psi at tick over for a short time

 

[GuidoK]

I my car from the oil pressure gauge i get between 15 and 20psi when hot at tick over and 55 to 60psi at revs over 4000rpm when hot

Interesting. The reason I ask, is that I saw in another topic (I think on zpost) that there are also s54 rodbearings available with larger clearance (so larger gap). From ACL bearings (HX bearings so 6b1569hx for the s54)
It took some digging but the enlarged gap is 0,001", so 0,025mm

And on the one side that makes sense. The stock rodbearing clearance for the s54 is 0,030mm to 0.070mm (in comparison, for the m54, which has a slightly smaller bearing it's 0,020mm to 0,050mm)
And there are lists with data regarding oil thickness and bearing clearance.
So for instance this article:
https://k1technologies.com/blog/bearing-clearance-and-oil-viscosity-explained
and this one:
https://www.enginelabs.com/news/what-i-learned-today-bearing-clearances-vs-oil-viscosities/
Mind you, all american articles, so measurements in inch.
And for thick oil, like 10w60 they advice quite the bearing clearance. Roughly between 0.0028" and 0.0033", so between 0,071mm and 0,083mm.
Considerably larger and adding 0,025mm clearance makes sense. (based on my experience, the clearance that you measure is pretty much inbetween the min and max value, so for the s54 that would make for a typical 0,050mm)
But again, US articles, US engines (usually a far cry away from european and japanese engines...)
And if I look at the low rev oil pressure, that is already pretty low. Rule of thumb is 20psi at idle (ok, also mainly based on US engines).
And enlarging rodbearing clearance typically gives lower oil pressure in low revs (there is more time inbetween strokes to refresh the oil film as the hole is pushed shut it's a pulsating feature unlike main bearings where the flow is continuous, which lower the oil pressure equally no matter what the revs as bearing clearance stays the same).

So I wonder if fitting rodbearings with larger clearance would be good or bad. If oil pressure at idle was higher maybe yes.