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Broken valve spring, really?

22K views 45 replies 25 participants last post by  Administrator jsvette  
#1 · (Edited by Moderator)
So, I limped home last weekend with a horrible misfire that suddenly appeared along with the Check Engine, Check StabiliTrak, and Check Rear Axle warning all in at the same time. The following day I had it towed in to my local dealer and it barely made it on to the back of that truck, nearly coughing itself to death in the process. When they got around to diagnosing the issue they started with electronics and even waited a day for the more experienced technician to get back from school. Today the most recent update went as follows:

One cylinder was low on compression and then it was discovered it had a broken valve spring. I'm still not quite sure why that would manifest itself with the particular error messages that it did given that it wasn't electrical. The service adviser had no answer either. I babied this thing during the break in period and had the first oil change at 500 miles and have never really put my foot to the floor just yet in 1300 miles. I only hope this isn't a trend I'm going to experience again down the road, maybe on the side of said road even. I love this car and think it looks incredible but my tolerance level has it's limits, mind you I'm not saying I'm at the end yet don't get me wrong.
 
#2 ·
my new 02' Ferrari 360 blew a couple valves with less than 1000 miles on it. I was doing 30 mph at the time.. and it was out of warranty if you can imagine.... it was a pricey repair to say the least but I still have the car and no issues since... these things happen....
 
#3 ·
I've read at least one other report on the forums about broken valves springs on a relatively new engine. IIRC, that other engine had 3 springs go. Sounds like GM needs to hold it's supplier to a higher standard.
 
#4 ·
Wow, that makes me feel a little better knowing it may not be completely random, I'll see if I can find that thread, thanks for the heads up Meyer...
 
#5 · (Edited)
At the same time, let us please put this into perspective, that there are over 85,000 C7's in customers' hands and only heard of over 15 or so with valve spring issues that we know of. Let us reasonably believe that there are another 30-40 which have had a valve spring problem that we have not heard of. Still less than 1/10th of 1% of all C7 motors.

Sorry power90801 that your's failed, and hope it is fixed immediately, but it remains a VERY isolated occurrence, and IMO, way too soon to assume that we both have a supplier problem AND/OR that GM has failed to do their diligence in this matter.
 
#8 ·
While I don't completely disagree, I don't think I heard of a single valve spring breaking when I was on the Miata forums, or Lexus forms, or Toyota, or Hyundai.....
 
#9 ·
I just picked up my 2016 C7 a few weeks ago. At 586 miles it broke a valve spring. I also babied the car during the break-in and had the oil changed at 500 miles. I got the car back yesterday and all seems right. The car was built in July 2015. I'm wondering if They got a bad batch of springs. On another corvette site a 2016 owner broke a valve spring one day before mine broke.
 
#10 ·
Mr.aqua, welcome aboard and congrats on your new C7 masterpiece. I hope that your Vette is back to 120% operating condition and your having a blast wheeling it around San Diego.

SF
Rick
 
#11 ·
Welcome to our forum Mr.aqua and glad your C7 is back to fine running shape. What model did you buy?
 
owns 2018 Corvette C7 2LT
#16 · (Edited)
As Mary Barra noted two weeks ago, there are 30,000 parts on a the car. Stuff happens to every brand, every model, every make, every version, every year.

Ferrari has had two recalls in the last year, though one of them they have refused to call a "recall," yet, interestingly, they are replacing all of those "not up to standard parts."
 
#17 ·
power 90801- I just had that experience yesterday in my 2015 C7, scared the crap out of me going down the highway, Luckily I was in a safe area at an exit ramp when it happened. Took it in for its 40,000 mile oil change the day before upon returning from a long road trip, You would think it would have shown up in a diagnostic report. Please tell me you haven't had any other problems.
 
#18 ·
I'm at about 5500 miles now with no further issues, knocking on wood with my other hand as I type this. That mileage includes a road trip of several hundred miles of which the car performed quite nicely. I hope it all goes nice and smooth for you with minimal issues in regards to your repair. It does suck though as it's always in the back of your mind, maybe way back in there but it's there nonetheless. It's the nature of the mechanical beast I guess, it's not perfect. Good luck!
 
#19 ·
I would say that the probability is very high that the people experiencing broken valve springs predominantly have them on the cylinders with AFM. The valve springs on the AFM cylinders are more complex, and, thus, more prone to failure.

All else being equal, MTBF (Mean Time Before Failure) is a function which correlates to the complexity of the design.

MissHenri, I hope you get this all squared away soon. Afterwards, you may choose (or may not, it is your choice) to keep your car from entering V4 by defeating the AFM. I exclusively use the paddle shifters in "M" mode. Others here use an AFM defeat device plugged into the OBD II port.
 
#20 · (Edited)
I would say that the probability is very high that the people experiencing broken valve springs predominantly have them on the cylinders with AFM. The valve springs on the AFM cylinders are more complex, and, thus, more prone to failure.

All else being equal, MTBF (Mean Time Before Failure) is a function which correlates to the complexity of the design.
I sure don't know much about this but I would think the valve springs are the same in the AFM cylinders. The cylinder "controller" may be different than the other cylinders but the springs shouldn't have a lower MTBF or be "more prone to failure". Maybe less prone since they're used less. Greater MTBF.

First I've heard this. Anyway, beyond me. Since some old Caddys, I haven't seen info that verifies AFM engines are more susceptible to problems/failure than non-AFM engines. Maybe there is real data somewhere. The never ending AFM discussion!
 
#22 ·
I think it is safe to say the valve springs on AFM controlled cylinders live in a little different environment and that could impact their failure rate. On the positive side they see less action when AFM is frequently active but on the negative side they will see more heat cycling as the cylinder goes between its "dead" mode and firing mode.

Put me down as an AFM skeptic as I noted in another thread. The AFM system adds complexity and weight, particularly for the base Stingray which gets stuck with a steel torque tube to help absorb NVH from AFM operation, and constrains some aspects of non-AFM operation (i.e. full potential of the VVT system). Although the LT1 operating in AFM mode does save some fuel versus when it is operating non-AFM I have a feeling that the difference would be far less between a LT1 operating in AFM mode versus a LT1 optimized without the AFM hardware and system.
 
#23 · (Edited)
rdslon01 and NSC5:

It seems to me an argument can be made the springs and lifters in an AFM cylinder actually receive less stress since they are not constantly under the strain of use and therefore have a greater MTBF. I also can't imagine an AFM cylinder, which under normal use is mostly engaged, goes thru any materially different "heat cycling" than the adjacent constantly operating cylinders.

The OP had only 1,300 miles on his C7 when the failure occurred. Therefore it can almost be factually stated AFM design had nothing to do with his failure. Nearly all C7s with that mileage or greater haven't suffered broken springs or lifters and they all have AFM.

Until we have hard data indicating an increased failure rate for C7 engines caused by AFM, I'm skeptical there is an AFM issue.

I'm hesitant going up against a coupla PhDs with just my lowly graduate degree but....:smile-new:
 
#26 ·
What year C7 do you have? Which type of car? Do you have the LT1 or the supercharged LT4? Do you know which cylinder had the broken valve spring?
 
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#25 ·
krauty, sorry you have to go through this and I'm sure it will be as good as new. I'm curious as to how many broken valves the SA has seen to label this a "common problem".
 
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#31 ·
not having good luck with corvettes lately.my 2015 (#25) GM bought back for trans problems torque tube and flywheel problems.this one is a 2016 base model and was fine till this.thank God it happened back here in Florida as i had just got back from a 3000 mile ride along the east coast. the service advisor says he sees a lot of corvettes with this problem.glad i have an SSR for transportation because they had no rentals, and won't use the commercial rental company they use.oh well just 1 more small problem in life
 
#32 ·
I have never been a fan of AFM because of the added complexity of what is in design a simple and reliable V8 engine. As in other of my posts on the subject; "If I wanted a four cylinder engine sports car I would have bought a Porsche".

Logic dictates that the risk of failure has to increase. But its a stretch to say that there is a design flaw. As pointed out by many here in the forum, LT1s can easily accumulate care free miles .... lots of them.....as did the LS series before it. Conclusion there is no fix to be had!

However, I seldom use AFM believing there is less stress in the LT1/4 running with all cylinders firing..
 
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#37 · (Edited)
Active Fuel Management
LMGTFY