[engeslen]

I was teaching a friend to drive stick. He accidentally shifted from 6th to 2nd, the car immediately shut off at about 100MPH. Over rev'd for about a few seconds.

All valves hit pistons, lost compression, 90% on all cylinders, exhaust carrier tabs broken...I almost killed him but..

I luckily have an extended warranty and they covered the repairs and BMW installed a new cylinder head in my car with all new bells and whistles. The car only has 44K miles.

I could not get mad as he did not know you can do that, it was my fault for not explaining things more thoroughly. But it sucked I tell ya, $8K later, I have a rebuilt engine.

My question is, they have given it a thorough inspection, and I finally have the car back after 4 weeks, and a new top end I guess, should I be worried about any other components?

The car drives well, bmw broke it in, and almost feels like I have a little more torque, but I'm worried about damage to the pistons and why they determined they were still ok... could it be possible that the exhaust valves can hit and just cause minimal to no damage at all? Should I watch anything like a hawk?

I asked if they checked on the clutch and transmission, apparently they hired a BMW engine builder and everything is copacetic. This is just for my own sanity.

No more joy rides or manual trans teachings in my future, no matter how dear you are to me. Thank you all for your time.

[F30RiK]

Woww youre so lucky bmw did that. if its like honda, dme should have stored a over-rev condition = no more warranty

[engeslen]

I know right? They totally stated that the factory warranty would not cover it as it would be operator error, but my extended warranty is with a third party, and I lucked out.

[mike-y]

from what i've seen, the valves will leave marks on the pistons. As long as the pistons didn't crack, the marks are just cosmetic. Since they took the head off, and inspected the pistons, I wouldn't worry about it.

I have no kind words for your friend tho

[misterjim]

Originally Posted by engeslen

I know right? They totally stated that the factory warranty would not cover it as it would be operator error, but my extended warranty is with a third party, and I lucked out.

Who is your third party warranty thru? What are terms and how much did you pay? Sounds like a good one!

[engeslen]

Its through Continuous Customer Care 1-800-332-0712 hope its ok to post this on here. I paid $4,700 and its a 5 yr, 60K mile electrical and drive-train warranty 0$ deductible.

They pay for everything, lodging if your stranded, tow, rental, etc... Its their platinum warranty.

Boy am I glad I did that. They will go through inspections and check out engine codes, but if you did not do anything stupid, they will work with you.

[Efthreeoh]

Wait, why on earth would one downshift at 100 MPH? I could see hitting 3rd from 6th, but second?

[engeslen]

Yea he had no clue, he was genuinely upset and still is, he's not a car guy. He will no longer be driving my car though lol

I'm glad some sort of over rev protection kicked in, or it was just the immediate loss of compression from floating valves right away, but we were able to coast to a stop without issues.

[Efthreeoh]

Originally Posted by engeslen

Yea he had no clue, he was genuinely upset and still is, he's not a car guy. He will no longer be driving my car though lol

I'm glad some sort of over rev protection kicked in, or it was just the immediate loss of compression from floating valves right away, but we were able to coast to a stop without issues.

There is no mechanical over-rev protection; that's why sit was banging around in you top end...

[Vegetable]

Man that is awesome that they covered that.. I had a 2007 328xi with no warranty left and over revved it at 90 MPH going from 3rd back into 2nd (meant to go into 4th).. The engine was toast with bent valves, 0 compression, etc. I ended up trading that car in for $3,000 toward my new 435i. I still beat myself up for making such a novice mistake.

[engeslen]

Yea I was thinking the worst after 2.5 weeks of them inspecting and going through the engine codes, and I assume telemetry. I am pretty sure they can tell how high the engine was rev'd and at what speed we were going.

I think they have certain schedules regarding how long the engine over rev'd for, I know Porsche does, if you spend a certain amount of time red lining all the time, it can void your warranty.

[engeslen]

Vegetable Nice upgrade though!

[Vegetable]

Originally Posted by engeslen

Vegetable Nice upgrade though!

Thanks... definitely a silver lining.

[motoguy128]

Originally Posted by engeslen

Yea he had no clue, he was genuinely upset and still is, he's not a car guy. He will no longer be driving my car though lol

I'm glad some sort of over rev protection kicked in, or it was just the immediate loss of compression from floating valves right away, but we were able to coast to a stop without issues.

You were lucky. On motorcycle with smaller valves, usually the top of the valve stem mushrooms and snaps off and becomes a musketball inside your engine at 15,000+ RPM (on a 600cc). Usually destroys not only the valves, but put holes in the pistons, heads, scores the cylinder walls and you get debris in the crankshaft. The engine is a total loss at that point. IF your super unlucky, a piece of valve stem or head gets partially melted in the plastic intake manifold. After a few head cycles it comes loose..... and you get to repeat the process on the 2nd engine. Ya!


If the manual is geared similar to the automatic, and I think it is, that's right around 11,0000 RPM. Figure a little wheelspin and slipping clutch and probably peaked 10,000RPM. At that speed, the valve stock springs are too soft to control the valves, so they "float" meaning they don't close quick enough to follow the cam profile at that speed.