Dumb Question Thread - No Flaming Allowed

[K-Dawg]

Theoretically you could reduce the spring rates to achieve the same bounce frequency or ride height, but your weight changes aren't very significant and you could end up doing more harm than good unless you are a suspension expert.

I assumed HanSooloo is referring to the engine air intake filter housing.

[jet_dogg]

The only thing you'll probably feel will be the wheels but I think what you're trying to do is a pointless exercise.

[zzyzx85]

Do emissions test readiness monitors get reset if I clear "sporadic" type SES codes?

[Nate047]

Dumb question, is there a break in period / procedure for rod bearings? Just want to dummy check

[oceansize]

Dumb question, is there a break in period / procedure for rod bearings? Just want to dummy check

Rod bearing break in is discussed in this thread, see post 7 by obi.

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/42670-break-in-procedure

[jdamore44]

I need to finally button down my Rod Bearings, Is the "standard" size the way to go? What would I need to consider for other options? Thanks! https://www.amazon.com/dp/B079G56GR4...v_ov_lig_dp_it

[Nate047]

Rod bearing break in is discussed in this thread, see post 7 by obi.

https://nam3forum.com/forums/forum/m...k-in-procedure

So it's a mix of people saying break them in or just send it. Nice lol.

[DJAM3]

Swapped my steering rack and installed new lines. I accidentally let the reservoir run dry with the engine on during the bleed process. Will the system naturally bleed the massive amount of air that was sucked in? Right now there is a huge dead spot when turning the wheel side to side. I didn't get a chance to re-bleed it yet.

[Tbonem3]

Rod bearing shells are not piston rings. No need for break in. They'll be lubricated 100% of the time (assembly lube, then oil), unless there's a problem. If there were to be metal on metal, you'd be fucked at 2000 rpm or 8000 rpm.

Piston rings, in a freshly honed cylinder, need to seat.

[Nate047]

Rod bearing shells are not piston rings. No need for break in. They'll be lubricated 100% of the time (assembly lube, then oil), unless there's a problem. If there were to be metal on metal, you'd be fucked at 2000 rpm or 8000 rpm.

Piston rings, in a freshly honed cylinder, need to seat.

This is what the shop told me and what I thought from other cars in the past too.

[Tbonem3]

Prob a liability thing. Like, if something happened within that 1200 miles, they could blame you and not take responsibility, if they can prove (through ECU) that you exceeded RPMs.

[Nate047]

Yea what I mean is they told me just send it

[Tbonem3]

No I understood sry, just my opinion of why shops or bmw says to go easy for such a long interval (1200 miles)

[IamFODI]

Yes, rod bearings are supposed to be lubricated to the point that there is zero metal-on-metal contact. If that actually panned out in practice, there'd be no need for replaceable bearings. We'd just bolt the rods to the crank and be on our way. No need for all the expense and trouble of designing, manufacturing, speccing, and installing engine bearings, all of which is an engineering rabbit hole unto itself.

Also, "lubricated" vs. "metal-on-metal" is not a binary thing. There are all kinds of intermediate regimes, some of which involve contact that is not enough to cause seizure. Hence the fact that engine bearings have a finite lifespan, which is why we're having this conversation in the first place.

All of this is why literally every engine bearing manufacturer has guidelines for what constitutes "normal wear." None of them ever says your bearings should look like new unless something's horribly wrong.

Glyco, one of the main engine bearing manufacturers, has even described some amount of wear as not just normal but beneficial in some cases:

If the clearance is minimal there is good conformability between the bearing and crankshaft journal. This conformability is a result of material that is worn in some parts of the bearing in the order of magnitude of μms. This process leads to less local stress on the sliding layer, a better absorption of shock loads and less wear.

They have also published break-in instructions for some of their bearing types, e.g.:


Those intervals sure seem short, so maybe that doesn't do much to support a break-in period of hundreds of miles. Then again, it's probably not unreasonable to imagine that some people would take several hundred miles to rack up a minute of ~4k RPM usage ("1/2 n_MAX"), especially while they've been told to go easy on the car -- which they evidently should, given everything else above.

Does any of this directly support any given statement that S54 rod bearings take X miles to break in? No. What it does is suggest that rod bearing break-in shouldn't be dismissed out of hand, and that the whole "rod bearings shouldn't wear" idea is false.

Maybe they need hundreds of miles to break in, or maybe they don't. Maybe it's different for different materials, engines, clearances, etc. This is where engineering expertise becomes important, and in cases like this it's almost always best to listen to the folks who designed the machine.

[FBloggs]

So it's a mix of people saying break them in or just send it. Nice lol.

Because of the 10/60 wt oil.
I would Break-in for 1500 miles, 4k rpm max, and be sympathetic daily until the oil is at operating temp.
Days go by and I don't hit 4k rpm and it is still rapid.