[Chrisguilday]

I have a 2011 automatic 335i @125K miles that had a trans failure and caused it to over rev. I’m trying to get an idea how likely the engine seized just due to hitting a valve.

For context, my car is stage 2+ and lately the trans has been acting funny in automatic mode. Well today on the highway at 85 mph I gave it maybe 30% throttle and the trans immediately downshifted to way too low of a gear, tach instantly tapped out at 8K RPM for maybe a second and then the engine shut off. (I assume the tach won’t exceed 8K even if the engine does? So who knows how high it revved)

The car didn’t lurch or make any weird noises, it just shut off and then slowed down very quickly displaying a trans malfunction and engine malfunction. The car won’t start, just clicks now. There was a very faint over heating smell of some sort but I think it was coming from the trans. It does still go into neutral.

So my question: How likely is it that it just hit a valve? The only other possibility is that it bent a rod, right? but is that even possible from over revving with no load on the engine? Surely it would hit a valve before a rod bends, right? Lol. the second it shifted improperly I let off the gas and tried to put it into neutral but couldn’t do it fast enough. I’ll boroscope it sometime next week but I guess I’m just looking for reassurance that it’s just a valve.

I did check MHD codes and there was like 6 valve / cam codes that I think all ended in “short to ground” but I didn’t write them down though. I Cleared the codes and reset the car to stock hoping maybe the car was in a fail safe mode, but nothing changed. I think I can still grab the codes though. It also has XHP which I assume should give me the trans code, but I’m sure it’s just time to swap the trans out if the car is salvageable.

Also, I’m pretty mechanically inclined, I’ve done $15k worth of maintenance / repairs on this car myself, so with that said how hard is it to replace the valves?

Thanks!

[oVeRdOsE.]

I bought few 335 part from a local guy on this exact issue ; automatic money shift !

him it was damage to a piston and ring. He didnt look further, only boroscope and he part out the car.

If in your case is only the head, you might be in luck, but check the internal with a boroscope and then take decision.

if the engine is dead, part out, and get a manual, you'll might end up with a money shift, but at least this will be less frustrating since it will be based on your skills and not a machine

[Chrisguilday]

Originally Posted by oVeRdOsE.

I bought few 335 part from a local guy on this exact issue ; automatic money shift !

him it was damage to a piston and ring. He didnt look further, only boroscope and he part out the car.

If in your case is only the head, you might be in luck, but check the internal with a boroscope and then take decision.

if the engine is dead, part out, and get a manual, you'll might end up with a money shift, but at least this will be less frustrating since it will be based on your skills and not a machine

Lmao wow, didn’t realize this was a somewhat common issue, I thought I was the only one. How does a piston & ring become damaged from over revving? It just overheated or something?

[RealJ22]

Originally Posted by Chrisguilday

Lmao wow, didn’t realize this was a somewhat common issue, I thought I was the only one. How does a piston & ring become damaged from over revving? It just overheated or something?

The piston hits the valve and causes all sorts of problems.

[oVeRdOsE.]

I doubt this is common, I did not speak too long to the guy, I was there to buy parts.

n54/n55s are not 2jz, they dont like to rev to the sky.

[Chrisguilday]

Originally Posted by oVeRdOsE.

I doubt this is common, I did not speak too long to the guy, I was there to buy parts.

n54/n55s are not 2jz, they dont like to rev to the sky.

Hey I thought I’d send you a photo of the fault codes and see if any of them mean anything to you. I tried googling them but none of them seem relevant to my specific situation. And yes I know my HPFP is starting to die lol.

[Chrisguilday]

Hey guys have an update and a quick question.

I went to put a wrench on the 24MM bolt on the harmonic balancer (this is the crankshaft right?) and the bolt was completely loose, I could turn it with 1 finger with no effort. Aren’t these bolts torqued to like 280 FT/LB’s??

So that’s obviously not a good sign, right? I don’t understand the whole relation regarding the crankshaft bolt, the crankshaft, and timing, but I know I’ve read that they’re all related, meaning if the bolt is loose than the engine is likely not in time anymore. But how did the bolt become loose? Could it have happened from the sudden and immediate drop in RPM when the engine shut off? But I would think that could only happen if the bolt was reverse threaded and it’s not. Or could it happen from the piston hitting a valve from valve float? In my head I just can’t understand what would cause the bolt to back out.

Anyway, I tightened the bolt enough to try to turn the motor over (probably 50-60 FT/LB’s) and the motor would not turn over, the bolt would just keep tightening. Lastly I left the wrench on the bolt, hit the starter again, and the wrench moved about 1/2 an inch, so I don’t think the engine is 100% seized but very stuck. In doing that did I just put it even further out of time? Lmao.

Again I don’t understand the relation to all of this, can someone explain the relation to the bolt / crankshaft & timing and what may have caused the bolt to become loose? Is it possible it’s only out of time? If it was out of time would that make the engine hard to rotate? I’m assuming my engine is just completely done for, or is there still hope?

[Chrisguilday]

Well I drained the oil and checked the oil filter. I have an aftermarket drain plug that has a long magnet attached to it to grab any metal. There wasn’t a spec of metal or anything shiny in any of my oil or in the oil filter, nothing at all. As usual the drain plug did have a small amount of greyish black smudge, but it always has a little of this. No actual metal or anything sparkly at all though.

Next step is to boroscope the cylinders.

[Wolf 335]

Loose crankshaft bolt, ouch.

Valves are likely gone for a nap.

Good luck and keep us posted.