Rod bearing failure. What now?

[cornerbalanced]

The other night I was driving home, exited the freeway, and stopped at a red light. My car stalled. Weird, but it has been happening every now and then (chalked it up to a bad ground). When I turned the car back on, I heard a slight knocking, quiet enough to where I had to turn my music down to ensure it was actually coming from my car. Directly after, the light turned green, and I drove off--hearing the knocking/ticking increase with RPMs. At this point, I turned into the first parking lot I saw, turned the car off, and had it towed home.

Today, my mechanic came to inspect the car. We took out the filter, to find a considerable amount of copper shavings. See pictures below. Suffice to say, one or more of my rod bearings have failed. Surprisingly, when searching about this topic, I found VERY little. I will chalk this up to the old m3forum dying. With the lack of information/discussion on this matter out there, I figured I'd start my own thread.

I am ultimately left with limited options. Hoping you guys could help steer me in the "right" direction.

Option #1: Drop the oil pan, further inspect for damage, if the crank is not visibly damaged, plasti-gauge the crank to insure it is still within factory tolerances. This will set be back roughly $900. My biggest concern is that it will ultimatly be for nothing (damaged crank), and I will be throwing $900 down the drain for nothing. If by some miracle the crank is unscarred, simply install fresh bearings, and be vigilant about fully flushing the contaminated oil.

Option #2: Source a core. Throw the fresh VANOS unit from my engine onto the core, throw rod bearings in, and install the core into my car.

Option #3: Rebuild my engine, expecting a new crank needing to be soruced. Mahle Motorsport pistons, forged rods. Machined block. The works.

What would you guys do in my shoes?

[cornerbalanced]

Pictures

[Gt4]

The other night I was driving home, exited the freeway, and stopped at a red light. My car stalled. Weird, but it has been happening every now and then (chalked it up to a bad ground). When I turned the car back on, I heard a slight knocking, quiet enough to where I had to turn my music down to ensure it was actually coming from my car. Directly after, the light turned green, and I drove off--hearing the knocking/ticking increase with RPMs. At this point, I turned into the first parking lot I saw, turned the car off, and had it towed home.

Today, my mechanic came to inspect the car. We took out the filter, to find a considerable amount of copper shavings. See pictures below. Suffice to say, one or more of my rod bearings have failed. Surprisingly, when searching about this topic, I found VERY little. I will chalk this up to the old m3forum dying. With the lack of information/discussion on this matter out there, I figured I'd start my own thread.

I am ultimately left with limited options. Hoping you guys could help steer me in the "right" direction.

Option #1: Drop the oil pan, further inspect for damage, if the crank is not visibly damaged, plasti-gauge the crank to insure it is still within factory tolerances. This will set be back roughly $900. My biggest concern is that it will ultimatly be for nothing (damaged crank), and I will be throwing $900 down the drain for nothing. If by some miracle the crank is unscarred, simply install fresh bearings, and be vigilant about fully flushing the contaminated oil.

Option #2: Source a core. Throw the fresh VANOS unit from my engine onto the core, throw rod bearings in, and install the core into my car.

Option #3: Rebuild my engine, expecting a new crank needing to be soruced. Mahle Motorsport pistons, forged rods. Machined block. The works.

What would you guys do in my shoes?

If you go option #2, please replace EVERY seals, gaskets, o-rings, …, as possible!

IMO, try to DIY the rod bearings job at home if you have a garage.

[maw1124]

I'd need to see the time and money difference between options 2 and 3. But I'd probably try to go option 1 and if that's not available go straight to 3. Once you're changing engines, any incentive to stay close to OEM spec goes away for me. At that point, build it the way you want it, as if you only have to sell one of them to yourself (as opposed to 80 thousand of them to some marketing bell curve).

maw

[Gt4]

Option 3 seems like a waste of money if you don’t go with a serious FI setup

[cornerbalanced]

Option 3 seems like a waste of money if you don’t go with a serious FI setup

That’s what I was thinking. Forged pistons and rods won’t really result in a material difference in power, ultimately a waste if I don’t go FI.

[GyroF-16]

May I ask the miles on those rod bearings?
And how much of their life that you were driving the car (vs previous owners)?

[cobra]

I would try option 1. Take it apart. Inspect. The bearings are sacrificial, so if they haven't been chewed through to the point of scoring the crank badly it might still be fine.

[Tbonem3]

Shouldn't a $1800 rod bearing job be in the budget anyway? Just do it like you would have anyway (assuming the bearings had ~100k(+).

[cornerbalanced]

Shouldn't a $1800 rod bearing job be in the budget anyway? Just do it like you would have anyway (assuming the bearings had ~100k(+).

Just worried the crank will be damaged, and I’ll have sunk $900 into a dice roll of whether or not my crank will be in perfect condition after hearing the motor knock. It is very tempting to do so however.

My mechanic has agreed to exchange labor for my damaged core. If the crank is fine, he’ll give me some money on top. If it’s damaged, I’ll give him some money on top. Makes the idea of a new motor easier to swallow.

A local forum member has tentatively offered to sell me his ‘built’ S54 (forged pistons, rods, 288 cams, 87.5mm block bore) which is immensely tempting, the only thing is, the engine is consuming oil, and will likely need further attention.

[Flat-Six]

How does the crank look? To me, that would determine my approach/options...

[TexaZ3]

This is a discussion based on nothing - pull the bottom and see how the crank looks - THEN decide what you want to do.

[cornerbalanced]

This is a discussion based on nothing - pull the bottom and see how the crank looks - THEN decide what you want to do.

I’ll likely do this. Just not confident my crank will be in great shape after hearing the engine knock.

[maupineda]

If all else was good, then just replace what needs to. Second hand crank or buy new. Either way you are in for an expensive misshap

[bigjae46]

Option 2 is the best balance between cost and reliability.

But option 3...A new BMW crank isn't THAT bad...looks better considering the prices of S54s have gone up considerably. You can probably replace the crank and the offending rod. Then clean up the engine really well and pray the oil pump is good to go. There is risk here.

But...option 2 is still the best option. And you can part out the old engine and make a good chunk of your money back. Lang was buying damaged cranks...not sure if they still are. I bought a lot of 3 damaged S54s, sold the bad cranks to Lang and made about half of my money back. VAC buys blocks and heads but...they are a**holes and will lowball you. They tried to give me $100 for a good head when they sell a simple refurb head for $1200...I can get the same head cleaned, pressure tested, and new stem seals for half that and not have any of the typical VAC issues.