THE BMW M54B30 (AKA e46 330) ENGINE- GOOD, BUT WITH A HUGE, ENGINE SMASHING, WALLET DESTROYING, FLAW...

About a year ago I was in the market for a new daily driver and part time drift car, and thanks to E46 BMW prices being absolute rock bottom at the moment, an E46 330i Sport was the winner. The 330i is powered by the 3ltr M54B30 engine, and it was ok, but less revvy than I expected; feeling a bit dead beyond about 6000rpm. That turned out that was because the stock ECU is deliberately holding the engine back, partially closing the electronic throttle at high rpm. A remapped ECU totally wakes it up- Making it pull strongly to 7000rpm+ and feeling like a different, much better performing, engine.

I presumed BMW did this to make the M3 seem much more special, and maybe that's part of it, but there's another reason too- When you rev these things they explode in a fucking massive, engine wrecking, nothing worth salvaging, kind of way. Ever wondered why 325 and 328 engines are cheap and common and 330s cost so much more despite being so similar? It's because most of them are fucking broken!

My engine was running great, totally reliable and great, being both my hard used daily driver and used on drift days all over the UK with no problem. Then one day, at 6700rpm in 5th gear, the oil light came on, and stayed on, and it sounded like a bag of nails. I knew this meant game over for the engine, and seemed likely the oil pump failed. But I didn't know why. Well, it turns out it's because of this...

You know what that is? That's the nut that holds the oil pump pulley on! It turns out it's a VERY well known problem with 330i engines revved hard on track, and basically the harmonics of the 330i engine shakes it clean off, even though it's reverse threaded. The other, smaller, M54 engines don't suffer from this anywhere near as much; it's mostly a 330i thing.

So what happens? Well, the nut falls off, which then means the chain and pulley falls off, so the oil pump stops, meaning instant zero oil pressure, which as you can imagine, writes an engine off pretty instantly.
If you catch it super quick and at low rpm you'd likely get away with rebuilding the engine with new bearings etc, maybe a crank polish. That's debatable if it's worth doing over buying a good used engine, but mine fell off at 6750rpm and 3 figure speeds, and I likely didn't notice for at least 5 seconds, so it was deffo game over.
I limped it 5 miles home, and then thought 'fuck it, I'm not rebuilding it' so limped it as far as I could to my mates garage 10 miles away. Amazingly, it made it! Well, it got to about 200m away before it expired, and I coasted it the rest of the way.
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​What was the damage? Well, this...

Ever seen a cam worn down so much you can see inside it? No me neither, but it's pretty cool. That's a hole in the sump from a conrod in the 2nd pic. 3rd pic is the oil pump with the pulley that had fell off. 4th pic is the alternator bracket with a hole in as the conrod went flying through the block and that too. 5th pic is, among other things, a very bent and broken rod. And 6th is the remains of a cam bearing cap after being ran with zero oil for about 15 miles!
So what the hell fuck can you do about it? As it's mega common, and pretty flippin' disastrous lots of people have looked for a solution. There's a few expensive things that 'seem' to fix it, and a few cheaper things that seem to just delay the inevitable...

So, 'fixing' it. Well first up, BMW clearly knew of the problem, in fact to the extent they fitted a different nut to later engines (bottom right) which basically just seems to have thread lock on it. This supposedly helps, as it seems almost any M54B30 you take apart, even low milers in good nick, will have a loose nut, and earlier ones are worse regardless of miles, BUT it will still happen in the end, threadlock or not.

Another 'solution' is lockwiring the nut in place (top left). You can even buy kits for this, but again, it delays it, not fixes it. The entire pulley ends up shearing off.

Next up is almost the same solution and same 'in the end' fail, spot welding the nut in place, as the top right pic shows.

A better solution is a modified pump with a 4 bolt pulley, as per center bottom. Shame it costs about 750quid, which is nearly twice what a used engine costs.
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Because it's crank harmonics that cause it, an ATI crank damper (bottom left) supposedly helps too, but again, it's big money, which turns most the appeal of a 330i in the UK (ie they're cheap as chips) down a little.

Best of all, but serious money that would certainly make you wonder why you didn't buy an M3 in the first place, would be a dry sump setup (top centre).

So what have I done on mine? Well, I picked up a low mile engine for £450, got the nut spot welded in place, which deffo isn't the full solution, BUT I hope it lasts a long time. Finally, partly as I wanted one anyhow for performance reasons, and partly as it's entirely possible it will change the damaging harmonics to a different RPM that it's no danger any more (but literally no way to know, it's SWAG- Scientific Wild Ass Guess, but a hopeful one) I've got a super lightweight flywheel to replace the fucking mental heavy dual mass setup they come with.

WILL IT LAST LONG? FUCK KNOWS! But the theory is fairly sound, I'll pray to He-Man that he can help it hold together, and one thing's for sure, I'll have fun until the time when it does happen again, if it happens.

If it does fail, I'll let you know!