[E92inAZ]

oh fellas, I'm having a bad day.
I enjoy(ed) daily driving my 2007 328i e92 coupe with the N52B30AE and automatic transmission, tastefully modified with the AFE air box, BMW 3IM intake manifold, AA catless headers and BPC stage 2 tune even though it has 140,000 miles on it.

I was under normal acceleration onto the freeway and the car just quit. I have the automatic but it felt like a manual that had been kicked out of gear. No CEL or any warnings but a strange buzzing sound like a fishing reel makes when you have a big catch fighting on the line. I coasted to a stop and had it towed. It would crank but not fire and there was just a little oil spatter on the passenger fender, right by the coolant reservoir. Other than that, everything looked completely normal.
Getting into it under the hood i saw that my valve cover was broken, from the inside! that was where the oil spatter was from. no good.
I pulled the valve cover off to discover the timing chain guide between my camshafts is broken and the timing chain is off the exhaust cam sprocket. It seems the guide between my camshafts broke, got pulled by the chain into the sprocket on the exhaust side derailing the chain, and throwing the shrapnel into the valve cover hard enough to break it.
see photos below of timing chain excursion and valve cover.

Now, I tried, repeatedly, to get this thing to fire and it cranked and cranked and cranked. I was also trying for better fault codes because it was only giving me vague cam codes and i wanted it to record more faults so i kept cranking it. Now that i see what it looks like on the inside I have NO idea how jacked the timing is on these cams in relation to each other but it safe to assume its VERY. I don't know that a standard compression test would work under these circumstances, SO: what I've done since is a quick leakdown test devised by what's around. I borrowed a compression test kit and a bore scope. First, I removed the timing belt tensioner and the bolts from the guides that I could get to, to give me some play in the chain. Then I removed the chain from the intake cam so each cam and the crank now turn freely and independently of each other. On each cylinder I turned the cams so the valves were closed, pulled the spark plug and screwed in the compression test adapter with the air hose fitting on it. I opened the valve on my air compressor to fill my 25 foot air hose with the 90 psi in the tank then closed it so only the hose was pressurized. Next, I attached the hose to the adapter that was screwed into the spark plug hole and that pressurized the cylinder with the 90 psi in the hose which, in every cylinder, pushed the piston down and held pressure for about two minutes while you could hear air slowly escaping, then they hissed like a half filled soda bottle when the hose was disconnected.
The bore scope showed that all the pistons are blackened, as expected, and they all have very valve shaped, half-moon clean spots on the exhaust side in the divots that are manufactured into the pistons. They really don't look like dents and the cylinders held pressure, so I don't know exactly what this means, but this is what I've got to work with. Either they're all fine (somehow!), or they're all knackered (but obviously not that bad)

so now my questions:
I bought the car with well over 100k on it and always thought that if the motor went, I'd like to stuff an N54 in it for the twin turbos, but with my parts and tune I'm right around the same power as a stock 335 (with no turbo lag) and none of my mods would transfer to an N54, so I think I want to stick to an N52.
Would you stick with the N52 or go turbo? I'm concerned with overpowering a 140k mile old transmission or rear end.
Is it even possible that I got away with throwing a timing chain and had NO impact of valves on pistons? or do you think they all hit, that's why they all test the same?
Do I pull the head and have it checked just to be sure? if I do, are there known performance modifications to be done to a N52 head that could make it worth the cost of taking it to a shop?
I welcome your opinions because there is a wealth of knowledge and experience on this forum, which is why i keep coming back. This is my first BMW so I'm mining all data just to see what my options are - within reason, of course. I didn't just win powerball or anything and I still need to be able to pay my mortgage but if I'm putting in this amount of time, work and money, I'd like to see if I can get the most out of it.

cheers!

[Phyrexia]

I've never experienced this myself, so I don't know what they look like, but I direct your attention to the following Google Images search: https://www.google.com/search?q=pict...=u&source=univ

Did your pistons look like those?

[Biginboca]

Wow that’s a new issue I haven’t seen reported on here yet. Sorry to read about all this.

It looks to me like your exhaust valves have hit every cylinder. I’m guessing in some way that chain kept the intake side moving in time while the exhaust valves hit all the pistons while the engine and camshafts spun down when your engine died.

Your best bet from here is to gather more data and at the lowest expense. Need to figure out how to get that chain back on, get the exhaust valves in time, and then do a genuine compression test. This should cost nothing but some of your time and then you can make a better decision of what to do next.

Dropping a n54 into that car wouldn’t be on my list of go to’s. I assume you would want to do that to run more than stock N54 power which means you would need stronger diff, axleshafts, tranny, brakes, etc etc. Better off to start over with a n54 car they are so cheap and you’ll save hours up hours of parts swapping even if you n54 car needs some maintenance or engine refresh you would be doing that to the n54 swap motor you bought anyway.

So the last option in my mind if your engine is toast is to swap in another n52 or part it out and start over. Depends on how handy you are. Seems like you are pretty handy and have access to tools so an engine swap would probably be my recommendation. The rear ends in these cars seem to hold up ok and if not they are cheap ($250ish delivered) on eBay. I would actually try to find a n52 with a manual tranny to swap that in, but that’s just me. Seems like the manuals have better resale besides being a bit more fun.

[E92inAZ]

Thank you for your replies. I followed the link to images (don't know why I didn't think of that) and yes, it seems every piston has hit valves. It looks like the least damaging of all the examples but thats just me tying to keep hope that this still isn't fatal. Which it is, obviously.

It seems, then, I'm looking at rebuild vs. swap. Used engines in my area seem to be about $2000 for anything under about 80,000 miles but they're all listed as N52N, not N52B30 and I'm concerned about how much is different between the two. Will there be sensors on the newer motor that my DME won't recognize, will my accessories bolt on, etc? I'd love to apply my tune to a base that started life with more horsepower and get some gains out of this nonsense but I've already done the post 100,000 mile replacements on the current (dead) engine - water pump, tstat, crank sensor, belts and pulleys, power steering pump etc. and all those within the 3 years I've owned the car so I'd like to swap those over if I could.

[rjahl]

Originally Posted by E92inAZ

Thank you for your replies. I followed the link to images (don't know why I didn't think of that) and yes, it seems every piston has hit valves. It looks like the least damaging of all the examples but thats just me tying to keep hope that this still isn't fatal. Which it is, obviously.

It seems, then, I'm looking at rebuild vs. swap. Used engines in my area seem to be about $2000 for anything under about 80,000 miles but they're all listed as N52N, not N52B30 and I'm concerned about how much is different between the two. Will there be sensors on the newer motor that my DME won't recognize, will my accessories bolt on, etc? I'd love to apply my tune to a base that started life with more horsepower and get some gains out of this nonsense but I've already done the post 100,000 mile replacements on the current (dead) engine - water pump, tstat, crank sensor, belts and pulleys, power steering pump etc. and all those within the 3 years I've owned the car so I'd like to swap those over if I could.

Don't worry too much about what the wrecker calls the motor. All N52 3 liters will accept the same bolt on's and sensors. Just swap over your parts to the new motor, if needed.

You will get different opinions but I believe you can find three different short blocks.

Early versions with the metal valve cover, N52. Early CVS system

N52k using the plastic valve cover. 2006 ish

N52k Sometime in 2008 the cylinder head was redesigned to reduce lifter noise.

They are all good motors if treated correctly,

[hassmaschine]

as long as it's not an N51 that you swap in, it will work fine. We didn't get anything but the N52B30 in the USA.

a swap is the way to go, an 80k motor has a long long life left in it, and a rebuild will be very costly (plus you still have to R&R).

[E92inAZ]

again, invaluable information - thank you for your input.

I'm looking around and I may be able to score one of a couple long blocks I've found with under 50k on them for right around $2000.00. There's a TON out there for half that price, but they're all over 100k miles and that puts me right back where I am now (minus the fatal failure).
There is one I'm looking at that says its got 10,460 miles on it out of a 2011 328i. How likely do you think that is? I'll give them a call to see where they got that number but while I'd really REALLY like to believe, I'm skeptical