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Discussion Starter #1
While driving home Thursday evening I hit the gas at a stop sign. I was 23.5 miles into my 25 mile commute. Nothing dramatic, just your usual 0-55 at a moderate pace. Then - check engine light flickers... car runs rough for .5 seconds... engine shuts down and power goes out... all the sudden on a narrow two lane road, I am looking for a place to pull over.

I posted a similar post in the Hard Start thread... but now I have some more information...

The engine code was PO300 (random cylinder misfire). The dealer said there were misfires on 2, 5 and 6. Low and behold, they have found a broken valve spring. Replacement on order. Additional damage to be checked Monday.

Stock 2003 Z06 with just under 31,000 miles.

Could the hard start symptoms I have experienced lately been related to the bad valve spring?

What should I do to make sure there isn't more damage to the engine? (What should I ask... I am far from mechanical when it comes to these things...)

Thanks for any assistance...

Craig
 

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Springs don't fail gradually, they either work or break. It's unlikely your hard start was due to the spring. If the spring had already been broken, it seems more likely the car wouldn't have started at all.

At the very least, you should have them bore scope the cylinder to check for signs of valve/piston contact.

It does seem that there are some "bad" springs out there. There's been an ever increasing number of "broken spring" postings over the last year or so. The way metalurgy works, odds are that the bad springs will come grouped together in batches. That would mean that engines in a given build sequence are likely to have a higher rate of failure. It also means that an engine that's had one failure is more likely to have another.

I would bite the bullet and replace all the springs with an aftermarket hi-po set. You *might* get GM to agree to cover some of the labor, at least.
 

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I feel your pain brother, at least it didnt total your motor like mine,warrantys are a good thing. good luck
 

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Discussion Starter #4
You Are not going to believe this...

Dealer says only issue is a single valve spring. I ask if they pressure tested the cylinders, inspected pistons and valves and scoped the cylinder and they say yes.

I go and pick up the car at 10:00 p.m. on Monday evening. I drove home slow and it seemed OK. Tuesday morning I go to back out of my driveway and I notice the red/orange engine cover is on the shelf behind me. I think maybe they broke it while conducting the repair and gave me the old one... Silly me.

On the way home from work, less than 50 miles after the repair, BANG... a puff of smoke comes into the cabin through the center vents, the engine misses badly, before shutting down at 55-60 MPH on Interstate 70 in Indianapolis. I manage to get the Vette to the right shoulder of the road and call the dealer...

I pop the hood... no engine cover on the passanger side of the engine. (I wonder what other parts of the repair were not finished...)

I am pretty sure it is tost now and am very mad at my dealer. I will probably draft a detailed letter voicing my displeasure when I get to my office this morning...

Craig
 

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ttt ... and?
 

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Discussion Starter #6
Dealer reports failure of a valve spring on a different cylinder. Within 50 miles of the first valve spring failure? The dealer is now seeking GM Warranty approval to replace all the valve springs. I have requested report with detail on all diagnostics including cylinder scope, compression test with tollerances measured, etc.

I am very concerned that this is the beginning of a long and bad engine related experience...

Craig
 

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They should give you some guarantee that the pistons are not damaged if the compression checks out. Warranty extension?

If you bent a valve, it should show up on compression test.
 

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The hard start is usually caused by a weak battery (at least thats what caused mine). I would try swapping out yours with a known good one and see if the problem goes away. As for the valvespring problem, if the springs were from the same lot, they will all probably fail around the same time (kind of like how all the lightbulbs in your house seemingly burn out around the same time). It is truely frightening about the number of spring failures that we've been hearing about lately.
 

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All valve springs should have been changed. Get ahold of the reg. mgr. and tell him the whole story. Once again piss poor GM work. Last but not least AK47 gets all work done right the first time!! :coo:
 

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Even though the stock springs might be a weak link, I would let them keep replacing them with stock parts as long as you are in warranty. Make sure you get it in writting from them that they did a leakdown test and the results. Like said above I would be calling the regional service manager, tell him that you want an extended warranty on the motor to at least 75k miles.

I broke a stock spring on my 01 at 67k miles (out of warranty), I replaced all the spring with dual cranes and some other items as well.

A compression test should tell you if a valve is bent, a leakdown test will tell you better.
 

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Discussion Starter #11
Just got off the phone with the service manager for my dealership. My service advisor is no longer with the dealership and I am being directly delt with by the service manager.

They are testing everything and will get me the results in a day or two, and pretty much assured me that it was going to be more than a valve spring repair this time.

I have asked to hear/see all test results and will add a leak down test to the list of things I am interested in. I am bummed not to have my Z for a while, but would rather it be done correctly than have to keep dealing with major engine part failures every 50 miles.

As for extending the warranty on the engine, I already purchased the dealer reccomended extended service plan (non GM) that carries me to 70,000. Is there value to asking GM to extend the engine warranty anyway?

Thanks to everyone who is assisting in my education on engines... I appreciate it, even if this wasn't the way I wanted to learn.
Craig
 

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I would ask for an extension to your warranty. Otherwise, the next time you have an engine problem, you will have to probably pay a deductible on your extended warranty to get the repair done.
 

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Discussion Starter #13
A new engine...

Service manager called shortly after they opened up the engine. The second valve spring to fail was sucked into the cylinder at the moment of failure. GM is sending a new engine under warranty. (With an additional 12,000 mile warranty.)

Anything I need to look out for with an engine replacement?

This is an OK scenario isn't it? (Better than rebuild with similar problems possible down the road...???)

Car is at 31,000+ miles now...

Craig
 

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chelmreich said:
Service manager called shortly after they opened up the engine. The second valve spring to fail was sucked into the cylinder at the moment of failure. GM is sending a new engine under warranty. (With an additional 12,000 mile warranty.)

Anything I need to look out for with an engine replacement?

This is an OK scenario isn't it? (Better than rebuild with similar problems possible down the road...???)

Car is at 31,000+ miles now...

Craig
Just make sure they put in an LS6 check part numbers on block and heads. Take it easy on the break in. Keep us posted. :cheers:
 

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Also make sure the tech puts all the stuff back on right.
Alot of bad workmanship out there.
If the first tech would have done his job right,they would have removed the head and checked everything, instead of just putting one new spring in and leaving the coil pack cover in your rear of your car.
If that tech in the one replacing engine LOOK OUT!!
 

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Discussion Starter #16
I know my service advisor from the first repair is "no longer with the dealership" and I believe I was told the tech from that repair is no longer there as well...

Engine is scheduled to arrive this afternoon after a short flight from Detroit. Estimated return between Wednesday and Friday of next week.

Craig
 

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Discussion Starter #17
Rental Car

Requested something nicer than a Toyota Tercel for my loaner and got a bright yellow Cobalt today. Not quite what I had in mind, especially since I gave them the weekend to find something appropriate. My wife, who is eight months pregnant picked it up for me. We had been told to expect a larger midsize car like a Malibu or Impalla... she was offered a Ford F-150 and the highlighter colored Cobalt...

I know it is in commercials with a Corvette, but really... is that the best that can be done under the circumstances...

Engine is being put in and car should be back to me Wednesday or Thursday...

I'm going to have to search the board for break in advice for the new engine...

Craig
 

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Had a similar experience. Driving along at 75 on the Interststate, car suddenly runs rough,check engine light comes on,then all power and oil pressure gone. Find out that it is the valve spring and a bent valve. Head is ok as is the piston. I wouldn't trust the stock valve springs anymore. Just too many of them giving away. My car has 45K miles.
 

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Discussion Starter #19
Engine Replaced - Now Leaks Oil...

I have a new long block engine in my Z06...
Drives great, feels better than when i bought it. BUT... I have a line (actually three puddles in a straight line) about 2 inches by 16 inches wide of oil under the car after it sits overnight.

It is running very rich (my average miles per gallon is very low... approx. 14 mpg right now). Also there is some oil spray through the exhaust.

Is all of this normal for a new engine? (I got it back Wednesday evening and have 150 miles on it so far...

Thanks for any assistance.

Craig
 

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Hell no it not normal! Consider another shop. Get to a dealership that has a Vette tech who can fix that puppy. Talk to the regional rep.

Chas.
 
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