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Hey all,

I need some advice. My crankshaft broke in half on my 2015 Honda Accord Coupe V6 Manual. I assumed it would be covered under warranty however Honda Techline determined that I over revved the engine - which did not happen (and I have absolutely no reason to lie anonymously). I was on a two hour journey and driving about 70mph in 6th gear cruising in no traffic with my pregnant wife. The car made a grinding noise and shut off - no power, no steering and no brakes (quite scary). Made an emergency stop and had the car towed to the nearest Honda dealership.

They've had it for over two months now, replacing the battery and starter before doing the diagnosis that said I over revved the engine. Side note, according to the mechanics, I would have had to shift from 6th into 2nd gear... again, I don't have a death wish. They then demanded my loaner car back and told me that obviously it was my fault and all damages are my responsibility.

Moving forward after a week of deliberation, I reluctantly gave them permission to tear down the engine to see what the actual problem was. Turns out, the crankshaft was split in half, causing a mess of other problems, and that Honda was claiming that it was due to an over rev (that never happened). Oh and it'll cost me about $6-7000 to repair it.

I'm kind of at the end of my rope on this and I'll be getting a call from Honda in a day or two and I was hoping I could get some feedback on this. Is it even possible to break a crankshaft from an over rev??? Honda obviously isn't giving me any other theories of what it could've been otherwise they would be on the hook for the repairs so I'm kind of David going up against Goliath here.

Looking forward to any advice or questions from you fine people.

Thanks.
 

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I don't know much about this, but my first thought is that maybe the engine computer stores some history of how the car was driven, and are they using this as their proof? If that is true, would you have to prove whatever sensor measured that to be defective? I guess they figure that any lawyer that would be able to help you would cost more than a new engine
 
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I will say that I was with my wife driving in a mazda whatever when the car shifter somehow broke and the car instantly got stuck in a lower gear on the highway. Luckily nothing other than the transmision/gears was broke. Had to drive it off of the highway with a gear limited top speed of 25. This was 15 years ago. The mechanics did not believe her when we explained the problem. They all had that "yeah right" expression on their faces. Is it possible something like that happened to you?

ETA: She was not in the process of shifting or anything like that. Just cruising along at 60-65.
 

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Dang!

How does Honda know that you over-revved the engine?


Forget the 7K bill. Get a used engine from a junk yard. If you can afford it, get a lawyer if you feel like Honda's screwing you on this one.
 

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If what Honda said is true, then you would have all kinds of carnage besides a broken crankshaft.....you would have bent valves, valves hitting pistons and all kinds of other chaos inside the engine, did they mention any of that? I also think that the computer would have captured any information of the engine being 'over-revved' and should be able to prove that to you. Good luck.
 

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I know I read something in my owner's manual about the car recording things, sort of like a black box. I think it's the first thing in the manual, I suppose because some people might consider it an invasion of privacy. Not sure if you have the ability to turn it off or not.
 

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@MP1982: I’m usually suspect of a first post that presents a crazy story like this, but I’ll give you the benefit of the doubt you are not a troll. It is extremely rare for a crankshaft to break. It takes a lot of force and I’ve never heard of it happening on a Honda.

With that said, for a crank to break it generally requires a massive difference in torque on one end of the crank than on the other. For example if one piston hydro locked and stopped moving, as that piston’s rod bent it could possibly snap the crank. If a bearing totally seized, it could cause the crank to stop moving on one end but not on the other and cause it to break. A broken crank is almost always a symptom of a bigger problem. Lugging the engine abusively could possibly cause it to happen too - very harsh jolts under severe strain. But in light of how freak this is, I can understand the dealership being suspect of you doing something stupid. Cranks just don’t break.

But I also suspect the dealership needs reasonable proof to deny a warranty claim. While a mechanically forced over-rev is a plausible cause, I’d think the valves would have also bent if the crank snapped, but I could be wrong. After the tech broke down the engine, did he/she find anything else odd in the engine? Scored metal anywhere? A spun bearing? Bent valves? Did they show you the broken crank? What does the break look like? I clean snap? Any sign of a freak manufacture's defect? What part of the crank broke? You mentioned you were just cruising on the highway when it broke. Similar to "throwing a wrench in the gears," could anything else have broken inside your engine that could have locked the crank and snapped it? Absent other clues it may be hard for them to prove anything. But to be candid, this is so freak I can understand them citing negligence on your part. If you ever respond to this thread, I’ll be curious to see how this ends.
 

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If the crankshaft split in two, it sounds like a defect in the shaft steel itself. I would go talk to a lawyer if they're not budging on their stance. If they stand tough, legal action is pretty much your only recourse to change things.
 

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This is from the first page of my 2016 Accord owner's manual. Seems like they could show you proof if they had it and wanted too.

Event Data Recorders: This vehicle is equipped with an event data recorder (EDR). The main purpose of an EDR is to record, in certain crash or near crash-like situations, such as an air bag deployment or hitting a road obstacle, data that will assist in understanding how a vehicle’s systems performed. The EDR is designed to record data related to vehicle dynamics and safety systems for a short period of time, typically 30 seconds or less. The EDR in this vehicle is designed to record such data as: • How various systems in your vehicle were operating; • Whether or not the driver and passenger safety belts were buckled/fastened; • How far (if at all) the driver was depressing the accelerator and/or brake pedal; and, • How fast the vehicle was traveling. These data can help provide a better understanding of the circumstances in which crashes and injuries occur. NOTE: EDR data are recorded by your vehicle only if a non-trivial crash situation occurs; no data are recorded by the EDR under normal driving conditions and no personal data (e.g., name, gender, age, and crash location) are recorded. However, other parties, such as law enforcement, could combine the EDR data with the type of personally identifying data routinely acquired during a crash investigation. To read data recorded by an EDR, special equipment is required, and access to the vehicle or the EDR is needed. In addition to the vehicle manufacturer, other parties such as law enforcement that have the special equipment can read the information if they have access to the vehicle or the EDR. The data belong to the vehicle owner and may not be accessed by anyone else except as legally required or with the permission of the vehicle owner.
Service Diagnostic Recorders: This vehicle is equipped with service-related devices that record information about powertrain performance. The data can be used to verify emissions law requirements and/or help technicians diagnose and solve service problems. It may also be combined with data from other sources for research purposes, but it remains confidential.
 

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This is from the first page of my 2016 Accord owner's manual. Seems like they could show you proof if they had it and wanted too.

Event Data Recorders: This vehicle is equipped with an event data recorder (EDR). The main purpose of an EDR is to record, in certain crash or near crash-like situations, such as an air bag deployment or hitting a road obstacle, data that will assist in understanding how a vehicle’s systems performed. The EDR is designed to record data related to vehicle dynamics and safety systems for a short period of time, typically 30 seconds or less. The EDR in this vehicle is designed to record such data as: • How far (if at all) the driver was depressing the accelerator and/or brake pedal; and, • How fast the vehicle was traveling.

@MP1982: So if the engine stopped immediately as you stated, and the EDR captured the last 30 seconds of engine operation, it might prove you were under light throttle at 70 mph, as you claim. If that rules out a money shift during those captured 30 seconds, it might make it far more difficult for the dealership to state over-revving was the cause. I think you owe @BLCKFLSH a big thanks!
 

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Thanks guys! Really appreciate that.

Again, thanks to everyone who responded. My family has had Honda's in our family for decades and I've never had anything less than a positive experience with them. So for this to happen isn't a sign of my destain or lack of trust for Honda by any means. I trust their product, just in this case I'm baffled.

And no I am not a troll, just not an avid forum poster. And I am not someone who would pull a stunt like that off... I get excited going from 6th to 5th, lol.

I really do feel helpless in the scenario and it looks like legal action may be in order. I appreciate all your time and effort responding, you're good people. I'm not sure if I can post pics but if so I will post the repair bill once I get it. It might paint a better story.

Please any other questions or advice is greatly welcome.

Best,
 

· Dsclmr:DIY @ YourOwnRisks
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If the crankshaft split in two, it sounds like a defect in the shaft steel itself. I would go talk to a lawyer if they're not budging on their stance. If they stand tough, legal action is pretty much your only recourse to change things.

+1. It's definitely defects in manufacturing. Even they admitted they rarely see such thing, and the only way for the shaft to split in halves is defect in material. Even if anyone wanted to try revving up to the sky, the shaft wouldn't split before the engine exploded. Lousy stealership. I guess you need legal advice if you didn't do anything out of ordinary.
 

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As several people have stated the computer records all the information to prove or disprove the engine over speed. Typically the crankshaft is not the part that breaks, in an over speed condition. The camshafts normally break first as they are spinning faster than the crankshaft. The computer would record camshaft RPMs as well as crankshaft RPMs so those need to be compared. Have them give you the data from the computer.

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Yes, you should be entitled to the data showing what was happening when it broke. After all, it's your car. There should also be proof that the data came from your car, at that moment. Good luck
 
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Even more mainstream than getting the EDR would simply be the freeze frame data at the time the crank snapped. I am sure there were probably a few dozen diagnostic trouble codes set fairly instantaneously. They record the exact time, RPM and about a dozen other sensor inputs when the DTC is set.

However - since they have monkeyed around and replaced the battery, I'd about guarantee that information is long gone. Do Honda's loose all the fuel trims, DTC's, etc. when the battery is disconnected?
 

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Not an engineer, so this might be off base, but...

When the shaft broke, could that have caused the engine to over-rev since it suddenly wasn't connected to anything any more?

How do they know if the over-rev was before or after the shaft broke? I doubt the event recorder would tell them when the shaft broke relative to the over-rev.

And shouldn't the RPM limiter have shut the engine down fast enough to prevent such a catastrophic event?

Too many unanswered questions for them to rush to judgment on this...

Just thinkin'... :wink
 

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I think this may be the most important part of the notice -

NOTE: EDR data are recorded by your vehicle only if a non-trivial crash situation occurs; no data are recorded by the EDR under normal driving conditions

Question is, would the EDR consider this a non-trivial crash for it to even record any info. Which leads to question the dealers statement of over-revving.

I would at minimum ask for proof of this condition, its duration and time of event. The over-rev could have happened only once any time prior. My guess is the highest RPM is recorded but not the date/time and that's enough for them to lay blame.
 

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I'm trying to figure out, how could the engine over-rev when the fuel is cutoff right at the red-line by the computer?? I'm honestly not sure exactly what would happen if say for example you went from 6th to 2nd and let the clutch out in this car with the computer nannies that are present. Back in the old days you could definitely destroy something in the engine or transmission (or melt the clutch I imagine) trying this, but with today's cars controlling how much you can rev...

I would start with calling Honda corporate or call another Honda dealer and see what their position would be. If you want to bring it up the line at the Honda dealer, speak with the service manager or the general manager of the dealership.
 

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I'm trying to figure out, how could the engine over-rev when the fuel is cutoff right at the red-line by the computer?? I'm honestly not sure exactly what would happen if say for example you went from 6th to 2nd and let the clutch out in this car with the computer nannies that are present. Back in the old days you could definitely destroy something in the engine or transmission (or melt the clutch I imagine) trying this, but with today's cars controlling how much you can rev...
The rev limiter is only meant to protect the engine from over-revving before an upshift, or when revving freely out of gear or with the clutch depressed. It cannot save an engine that is hopelessly over-revved by an accidental downshift into a low gear while traveling at high speeds. Say you accidentally shifted into 2nd while traveling 90 mph. The engine revs would instantly spike to 10,000+ as soon as the clutch was released and the entire valvetrain as well as the pistons would be immediately destroyed. The rev limiter wouldn't even have a chance to act in such an event.

I remember this happening to a few RSX-S owners back in the day, and those engines had much higher redlines than ours. The aftermath wasn't pretty...

I think the OP has a pretty good case here. Honda needs to provide more evidence in order to prove that an over-rev condition caused the crankshaft failure. If the crankshaft snapped due to extreme engine speeds, there would be extensive damage to the valvetrain and to the pistons as others have stated.
 
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