Red Oil Pressure Light comes on when idling (right after rod bearing replacement)

[yhp2009]

You are spot on with everything. S54 has some of the highest piston speeds of any production engine ever built, so the fact that we can get 100k miles on them is very impressive. Its the nature of owning a car with a racing engine, it comes with racing engine maintenance (because physics).

There isn't a magic oil clearance or bearing to "fix" anything, just a small window of right and a big window of wrong. The lowest stock clearance that I've measured was about 0.0017", with a larger clearance bearing you end up at the high side of what will work (0.0027"). I've put together engines with high clearances before (0.0028") and had hot idle oil pressure flicker, ended up taking it apart and using half and half bearings to get it down to about 0.0023" (which has been great in my current engine). Some S54s are at about 0.0023" stock, in which case that extra 0.001" will take you way out of a usable range and you will absolutely have low oil pressure issues.
I'd recommend taking it apart and inspecting the oil pickup O-ring, but also measure your clearances (at least on several rods). Plastigauge isn't the most accurate, but pretty decent at checking things on the car. You can also mix the bearing shells to get the right clearance. This is all way cheaper and easier than replacing or building a new engine.

Thats an interesting point. But, why do we not have more cases like the OP if many owners are doing it the "wrong" way. I doubt many people actually measure the clearance, yet most have success replacing their bearings with no problems.

[heinzboehmer]

It is genuinely scary! So many local shops plop in VAC coated bearings with ARP bolts and deem the car "fixed." This is straight up gambling.

I agree that to get perfect clearances everything must be measured, but the procedure that BMW specified for the rod bearing service bulletin did not include this. It just says to do what most people end up doing, which is to take the bearings out of the box and put them in the engine. I would imagine that if the bearing clearances varied enough to cause problems, we would be seeing a lot more 01-03 cars with engine failures, especially considered the replacements first started to be done like 15 years ago.

[sapote]

I agree that to get perfect clearances everything must be measured, but the procedure that BMW specified for the rod bearing service bulletin did not include this. It just says to do what most people end up doing, which is to take the bearings out of the box and put them in the engine. I would imagine that if the bearing clearances varied enough to cause problems, we would be seeing a lot more 01-03 cars with engine failures, especially considered the replacements first started to be done like 15 years ago.

For something with such critical clearance as rod bearings, at least one should double check the dimension of the bearing shells out of the box. Parts do mix up accidentally and you don't want to find out after everything was buttoned up. We're talking 0.001" or less could cause a major problem. It doesn't take much times to do this with a caliper.

If BMW Tis did not say to check the new bearings before install, it probably assumed the bearings they used had passed Quality Control department.

[yhp2009]

For something with such critical clearance as rod bearings, at least one should double check the dimension of the bearing shells out of the box. Parts do mix up accidentally and you don't want to find out after everything was buttoned up. We're talking 0.001" or less could cause a major problem. It doesn't take much times to do this with a caliper.

If BMW Tis did not say to check the new bearings before install, it probably assumed the bearings they used had passed Quality Control department.

Agreed, definitely will check when i get mine done

[R1pilot]

You are spot on with everything. S54 has some of the highest piston speeds of any production engine ever built, so the fact that we can get 100k miles on them is very impressive. Its the nature of owning a car with a racing engine, it comes with racing engine maintenance (because physics).

I have an S2000 with 200k miles that I bought brand new ... at around 30k miles I supercharged it ... never touched the bearings. Check those piston speeds.

The bearings on my M3 at 97k miles were toast.

I don't know if BMW got it right or no, Honda did.

[Icecream]

I have an S2000 with 200k miles that I bought brand new ... at around 30k miles I supercharged it ... never touched the bearings. Check those piston speeds.

The bearings on my M3 at 97k miles were toast.

I don't know if BMW got it right or no, Honda did.

The F20 is smaller, lighter, lower displacement and, I think critically, has a shorter crank. The S54 also has to deal with a heavier car and makes more power. It is just not comparable and without being the engineer that worked on the S54, I don't think anyone can say it was poorly designed. Any poor design would be an artifact of MBA's and accountants driving the decisions.

Also for what it's worth, plenty of S54's make it near or over the 200k mark, I have also read the F20 is not immune to bearing failure/replacement.

[digger]

The F20 is smaller, lighter, lower displacement and, I think critically, has a shorter crank. The S54 also has to deal with a heavier car and makes more power. It is just not comparable and without being the engineer that worked on the S54, I don't think anyone can say it was poorly designed. Any poor design would be an artifact of MBA's and accountants driving the decisions.

Also for what it's worth, plenty of S54's make it near or over the 200k mark, I have also read the F20 is not immune to bearing failure/replacement.

The F22 has essentially the same stroke and redline as s54.
The F20 with shorter stroke sees higher acceleration loads due to rpm^2 factor.
F20/22 and S54 make about same power per cylinder.
F20/22 bearing are 1mm smaller diameter but 3.4mm wider and thus 20% more projected area.

So they are fairly comparable yet they came up with fairly different designs.

note that BMW reduced bearing area from S50B30euro-->S50B32-->S54B32 obviously chasing less friction.
IMO the trend for narrower but slightly larger diameter rod bearings hasn't worked well for them as that's what they did with the S65/S85 as it has bigger problems than s54 and the loading is measurably lower on S65/85 due to the small stroke

obviously other factors at play to like actual delivery of oil to the bearing not just the loads

[Icecream]

The F22 has essentially the same stroke and redline as s54.
The F20 with shorter stroke sees higher acceleration loads due to rpm^2 factor.
F20/22 and S54 make about same power per cylinder.
F20/22 bearing are 1mm smaller diameter but 3.4mm wider and thus 20% more projected area.

So they are fairly comparable yet they came up with fairly different designs.

note that BMW reduced bearing area from S50B30euro-->S50B32-->S54B32 obviously chasing less friction.
IMO the trend for narrower but slightly larger diameter rod bearings hasn't worked well for them as that's what they did with the S65/S85 as it has bigger problems than s54 and the loading is measurably lower on S65/85 due to the small stroke

obviously other factors at play to like actual delivery of oil to the bearing not just the loads

hmm, yeah those are good points. There are just too many variables and objectives for anyone to say its poor design by BMW imo. Like I said, mine went 190k before spinning a bearing and I drive the car hard, that just cant be bad engineering and i dont think its fair to say that it is no matter which way you look at it. Its a remarkable achievement by the engineers actually.

I would go so far as to say any early failure is extremely rare in reality or if it is common it is more likely due to operator error and not warming the oil up properly despite what they say. To many (especially first owners) they see the tach lights off and its foot to floor. Speculation of course but it seems more likely, most people are not into oil temps as much as us haha.

[R1pilot]

The point was that pavlo said we are lucky to get 100k miles out of the bearings given the piston speed.

As digger pointed, the F20C has a higher piston speed. Mine dynoed at 371 rwhp at 9200 rpms on an Aus Dynamics ... it went 200k miles with factory bearings.

I currently have a supercharged F22c S2000 that has the rev limiter set at 8600 rpms, also dynoed at 39x rwhp and has 110k miles. Factory bearings.

Not saying BMW got it right or not ... but the being lucky statement I am not sure about.

[sapote]

The point was that pavlo said we are lucky to get 100k miles out of the bearings given the piston speed.

As digger pointed, the F20C has a higher piston speed. Mine dynoed at 371 rwhp at 9200 rpms on an Aus Dynamics ... it went 200k miles with factory bearings.

I currently have a supercharged F22c S2000 that has the rev limiter set at 8600 rpms, also dynoed at 39x rwhp and has 110k miles. Factory bearings.

Not saying BMW got it right or not ... but the being lucky statement I am not sure about.

Honda bearings material maybe quite different than BMW in addition to having wider bearing. The journals finish roughness could be the key too.

[Icecream]

Meanwhile I'm seeing how real the M tax is. King Rod Bearing Set Honda S2000 2000-2009 – Import Image Racing

We've all been had lol: ACL Rod Bearing Set 48mm Journal Bearing WRX 2002-2014 / STI 2004-2020 – Import Image Racing

[liam821]

The F22 has essentially the same stroke and redline as s54.
The F20 with shorter stroke sees higher acceleration loads due to rpm^2 factor.
F20/22 and S54 make about same power per cylinder.
F20/22 bearing are 1mm smaller diameter but 3.4mm wider and thus 20% more projected area.

So they are fairly comparable yet they came up with fairly different designs.

note that BMW reduced bearing area from S50B30euro-->S50B32-->S54B32 obviously chasing less friction.
IMO the trend for narrower but slightly larger diameter rod bearings hasn't worked well for them as that's what they did with the S65/S85 as it has bigger problems than s54 and the loading is measurably lower on S65/85 due to the small stroke

obviously other factors at play to like actual delivery of oil to the bearing not just the loads

I've said it once, I'll say it again. The s54 is a Honda F22c with two more cylinders. They're extremely similar in power per cyl/bore/stroke. Props to Honda, it's a simple extremely reliable engine that makes great power. I used to own a Honda S2000 and that car was dead crazy reliable.

[MTiz]

Figured I'd go ahead and update this thread. Got the car back on Saturday after paying for rod bearings a second time (proper clearance ACL bearings), and all the associated gaskets. Shoutout to FCP Euro for getting me all the parts within two days. My Indy thoroughly inspected my oil pump and it looked mint according to him. Put about 120 miles on the car that day, and the next morning (yesterday) the low-pressure light came on after the car fully warmed up.

Same symptoms as before, only comes on at idle. Not sure what to do at this point.

[MTiz]

Uploaded a video for reference

[heinzboehmer]

Damn, sucks that you had to pay for this twice and the issue hasn't gone away (hey, at least you got welcomed to the spendy part of m ownership). You mentioned a thorough inspection of the oil pump, but did you have the pickup tube o-ring replaced?

If yes, then maybe this is a sensor issue? I would suggest actually measuring oil pressure with a good old gauge before throwing any more money/parts at the car.