Under Valve Cover @ 255k Miles

[BMWM3186]

Welp, so much for my "amazing engine" brag post. The motor developed a knock. Doesn't sound like a rod bearing - it only happens when the engine is holding 2k-3k RPM with no load (holding steady speed through a parking lot, holding the engine speed in that range in neutral or clutch in). It sounds normal at idle and under load. Also cut open the oil filter and it's free of the usual spun bearing detritus. Replaced the chain tensioner, didn't help. My choices are replace the motor with a used example, rebuild the motor, or part it out.

Bummer

Uh oh. I'd love to know what the noise was coming from. How much did you track the car? It seems like a used engine swap would be a lot more cost effective than a rebuild, I'd probably go that route myself.

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[sean96gsr]

Yup, looking for a used ZHP motor. I don't want to part it out, but may still go that route. We will see. I'll definitely tear into the old one to see what the failure was. Speculation is that it might be a wrist pin. The car only has a few sessions on the track, nothing serious.

As an aside, what is a rolling chassis with a brand new cooling system, brand new Bilstein B8s and H&R sports at all four corners, Rogue short shifter, mint AL HIDs retrofitted with ZKW lenses, new Dr. Vanos kit, new brake pipes, new stainless steel brake lines, new cross-drilled zimmerman rotors & pads, new Pilot Super sport tires, control arms, poly CABs, poly RTABs, poly subframe bushings, TMS subrame reinforcement, BMW SIB epoxy injected subframe floor, and a super clean interior worth?

[BMWM3186]

Yup, looking for a used ZHP motor. I don't want to part it out, but may still go that route. We will see. I'll definitely tear into the old one to see what the failure was. Speculation is that it might be a wrist pin. The car only has a few sessions on the track, nothing serious.

As an aside, what is a rolling chassis with a brand new cooling system, brand new Bilstein B8s and H&R sports at all four corners, Rogue short shifter, mint AL HIDs retrofitted with ZKW lenses, new Dr. Vanos kit, new brake pipes, new stainless steel brake lines, new cross-drilled zimmerman rotors & pads, new Pilot Super sport tires, control arms, poly CABs, poly RTABs, poly subframe bushings, TMS subrame reinforcement, BMW SIB epoxy injected subframe floor, and a super clean interior worth?

Gonna depend the buyer I'd suppose. But I don't think you would get what those parts are worth that were put into it. I think you would be better off putting a motor in and then selling.

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[sean96gsr]

Uh oh. I'd love to know what the noise was coming from. How much did you track the car? It seems like a used engine swap would be a lot more cost effective than a rebuild, I'd probably go that route myself.

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Totally forgot to update this post! I swapped in a used motor that we took apart to reseal and upgrade a bit. I tore down the old motor afterwards and found this as the root cause. I finished 2/3rds of a track day with it making the knocking noise, AND drove it a few hundred miles. Not many motors would hold up like that with a badly worn rod bearing.

I *think* it was cylinder number 1, but it was a few months back so I don't remember exactly. I keep this on my desk now It looks a little extra-crappy in the photo because it came out months ago and I cleaned the excess oil off of it before I took it into the house.

[SaltyNC]

We are plagued with this kind of bearing wear in the S54 engine, but I didn't know it could also be a problem with the M54. Do you know if your other bearings looked similar, or was it just this one? The top of your engine looked amazing. Sorry this happened. I'm going to be doing a rod bearing replacement on my S54 soon. It probably won't take me more than 10 hours. Uggh.

Salty

[SaltyNC]

Just curious, did you happen to notice when you tore down the engine if the oil pump nut was still firmly attached?

Salty

[sean96gsr]

We are plagued with this kind of bearing wear in the S54 engine, but I didn't know it could also be a problem with the M54. Do you know if your other bearings looked similar, or was it just this one? The top of your engine looked amazing. Sorry this happened. I'm going to be doing a rod bearing replacement on my S54 soon. It probably won't take me more than 10 hours. Uggh.

Salty

The others were all fine. I don't think it's a major issue with the M54 though, at least not like it is with the e46 and e9x M3. This car had over 250k miles at the time, and when I bought the car it had an oil filter housing with a major drainback issue that caused the oil light to stay on for up to 5 seconds at each start. God knows how long the PO had left it that way. The shop I go to has a ton of high mileage e46s and this is the first time a motor had blown due to anything other than gross negligence.

[sean96gsr]

Just curious, did you happen to notice when you tore down the engine if the oil pump nut was still firmly attached?

Salty

Yup, still super tight, and the car had been tracked too. I think the oil pump nut thing is something that happened once or twice and somehow became a huge forum myth.

[SaltyNC]

Thanks for the info, Sean!