Bent valve! Causes and long term...

[scm6079]

My M3 apparently decided to eat a valve. After getting the engine malfunction nav display and a quite noticeable dropped cylinder or more while driving my local dealership just diagnosed a bent valve in cylinder 8.

Considering I was merely cruising at around 65 mph in 7th (DCT) on the highway when it happened, can anyone help me understand what could have caused this? Is there anything I should worry about with the dealer repairing this?

Thanks,
Scott

PS - I've probably been nicer to my M3 than any other car, no performance mods at all, no racetrack time, daily driver duty. Just over 16,000 miles. Average 20.6mpg even!

[dparm]

Did they inspect the piston to see if it collided?

[GT3 Tim]

Very odd. The only time I have heard of M3's eating valves is from over-rev. I did it once in my E36 M3. :-)

the only thing I could even think of is oil starvation/oiling issue. Have you been diligent in your oil changes? My car is also low mileage (only 20K on it since new in 2008). You have to change the oil every 6 months or so. Being as the car sits a lot, you will get a lot more condensation (water) in the oil. If it isn't driven a lot (with oil temps over 212), you won't burnt off (vaporize) the water.

That's all I can think of....let us know what you find out.

Edit: I see your car is newer...I was thinking it was an "old one" like mine. Never mind the above. I have no idea wth would cause it...please let us know what you find out.

[Vic311]

So the dealer took apart the head? Was it the exhaust or intake valve? Did they check the timing? If that is off it could account for the bent valve. I would also advise checking the piston.

[bruce.augenstein@comcast.]

Originally Posted by scm6079

My M3 apparently decided to eat a valve. After getting the engine malfunction nav display and a quite noticeable dropped cylinder or more while driving my local dealership just diagnosed a bent valve in cylinder 8.

Considering I was merely cruising at around 65 mph in 7th (DCT) on the highway when it happened, can anyone help me understand what could have caused this? Is there anything I should worry about with the dealer repairing this?

Thanks,
Scott

PS - I've probably been nicer to my M3 than any other car, no performance mods at all, no racetrack time, daily driver duty. Just over 16,000 miles. Average 20.6mpg even!

Yeah, we know you've only driven it back and forth to church , but your dealer will tell you if you did a money shift or not. If not, you're covered, and probably no harm done except for a possible piston gouge, which they can address.

If you did do a money shift, they'll know, so be prepared to open your checkbook wide.

Bruce

PS - Did a money shift (3-2 instead of the attempted 3-4) on an E36, and a new long block (installed) cost me $8800. Bummer.

[s85e90]

Most likely the valve spring failed which has happened a number of times on these cars. Yours just got worse luck and collided with the piston to bend the valve



Edit: I say most likely but due some searching and you'll see similar cases; I would bet this is the problem;

Good luck!

[Vic311]

Originally Posted by s85e90

Possibly the valve spring failed which has happened a number of times on these cars. Yours just got worse luck and collided with the piston to bend the valve

Possibly, but the dealer would have then diagnosed it as a broken valve spring with the bent valve being a result of that. Over-rev, timing issues are the likely culprits.

[s85e90]

Originally Posted by Vic311

Possibly, but the dealer would have then diagnosed it as a broken valve spring with the bent valve being a result of that. Over-rev, timing issues are the likely culprits.

we're talking about BMW techs. It's probaly semantics in the way it was relayed to OP; either way Good luck OP

[kerrit]

there are a few reports on this forum of bent valves if you search. Theory is a bad batch of valve springs used on our engines.

[AWAirFlow]

may be broken valve spring. they have to take it apart and check. techs told me it was bent valve before opening it up and realizing it was a broken valve spring.

[SenorFunkyPants]

Originally Posted by Vic311

Possibly, but the dealer would have then diagnosed it as a broken valve spring with the bent valve being a result of that. Over-rev, [........] are the likely culprits.

Over rev in a DCT is unlikely though not completely impossible.

[V8FunNaturally]

average 20.6mpg ?! wow who gets such an average on an M3. I don't think you can brake-in the engine properly if that was your mpg average during break in too.

At least you're lucky it happened under warranty. Sounds like your car was bought in 2012. I have a 2013.9 (I consider it the 2014 model ) and don't have 4,000 miles on it yet. I make sure to take it on longer trips once in while so that all the fuel and water that condensate in the oil has time to fully evaporate. I've read that condensation will raise your oil level and if you were near overfilled could possibly this lead to such a failure ?

[Petros]

Originally Posted by SenorFunkyPants

Over rev in a DCT is unlikely though not completely impossible.

How would you overrev a DCT without something else failing before hand to allow it? I thought the car will always override any commands to the gearbox that will lead to overreving provided everything is working the way it should

[dparm]

Originally Posted by sunsweet

average 20.6mpg ?! wow who gets such an average on an M3. I don't think you can brake-in the engine properly if that was your mpg average during break in too.

I just did 20.1mpg on my last tank. If you're cruising at about 70mph on the highway for most of the tank, it's definitely attainable.

[scm6079]

Originally Posted by sunsweet

average 20.6mpg ?! wow who gets such an average on an M3. I don't think you can brake-in the engine properly if that was your mpg average during break in too.

At least you're lucky it happened under warranty. Sounds like your car was bought in 2012. I have a 2013.9 (I consider it the 2014 model ) and don't have 4,000 miles on it yet. I make sure to take it on longer trips once in while so that all the fuel and water that condensate in the oil has time to fully evaporate. I've read that condensation will raise your oil level and if you were near overfilled could possibly this lead to such a failure ?

Originally Posted by dparm

I just did 20.1mpg on my last tank. If you're cruising at about 70mph on the highway for most of the tank, it's definitely attainable.

Yup, bought in 2012 -- and I drive mostly highway cruising at ~65-75mph.

I fired off an email to the dealer asking about piston contact -- but kind of assumed the answer was yes from their first call. Hopefully I was wrong. I'm waiting to hear back from them now.

[SuitedPair]

Originally Posted by kerrit

there are a few reports on this forum of bent valves if you search. Theory is a bad batch of valve springs used on our engines.

Broken valve spring here. 2011 M3 with around 1500 miles. You'll find more of us by doing a search.
At 33000 miles now. Nothing else has broken...yet.
I'm more of a 15-16mpg'er
Good luck with repairs.

[V8FunNaturally]

Originally Posted by dparm

I just did 20.1mpg on my last tank. If you're cruising at about 70mph on the highway for most of the tank, it's definitely attainable.

I know but it sounds wrong to buy an M3 to use it like that tank after tank. A 328i can cruise on the highway just fine.

[V8FunNaturally]

Originally Posted by scm6079

Yup, bought in 2012 -- and I drive mostly highway cruising at ~65-75mph.

You drive mostly on the highway but how many minutes each time ??
if it's less than 30 minutes each time the gas in the oil does not have time to evaporate.

[4corners]

Originally Posted by dparm

I just did 20.1mpg on my last tank. If you're cruising at about 70mph on the highway for most of the tank, it's definitely attainable.

My average mpg has gone from 20.1 pre benvo tune and crept up to over 23 mpg and i drive it harder all the time. i posted a pic on here somewhere.

[SenorFunkyPants]

Originally Posted by Petros

How would you overrev a DCT without something else failing before hand to allow it? I thought the car will always override any commands to the gearbox that will lead to overreving provided everything is working the way it should

It goes something like: go over a hump backed bridge fast enough that your wheels leave the ground and with engine at high revs. In a panic and while still airborne, you lift off the throttle , brake and shift down....Gearbox software thinks its safe to shift down but when you hit the ground you overspeed the engine
Like I said its unlikely.

[M3Captain]

Broken spring lock or worn valve guide. If there was no piston contact and you didn't continue driving it you may be ok. Post up when you get a diagnosis from the dealer.

[dparm]

Originally Posted by sunsweet

You drive mostly on the highway but how many minutes each time ??
if it's less than 30 minutes each time the gas in the oil does not have time to evaporate.

The amount of fuel in the oil is going to be extremely low. These are not direct injection motors. My most recent UOA showed the fuel content as being "under 0.5%", which is effectively 0. Other UOAs posted here show similarly low numbers.

I would worry more about moisture in the oil, but even that will be burned off within a few minutes of the oil passing the 160 F mark.