When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Back in December, I noticed a loud ticking sound coming from the engine in my 08 Z06 with 75k miles. I decided to play it safe and took it in for inspection at a local chevy dealer (not my first choice but my dad has serviced many vehicles there). At that time they thought it might have had something to do with one of the head gaskets but I kept thinking it had something to do with the valve guides. I expressed my concerns to the service manager who put me in contact with the lead mechanic who assured me that their original repair estimate would include a fix for this. As I was trying to describe the exact issue to the mechanic, he stopped me and said he knew exactly what I was referring to and would take care of it. Fast forward about 3 weeks later and my car is returned with a $5k invoice. The invoice included some parts, labor and subcontracted work to a machine shop for the heads. I know this is probably more than what I would have paid by going straight to AHP but I figured as long as it's fixed, I'm happy to have caught it before any real damage could occur.
Here's what the car sounded like the night I noticed it sounded strange.
After finally getting the car back, the ticking sound seemed to have went away and I thought everything was fine. Then last Sunday (2/4/18), I'm driving down the 91 eastbound on my way home and I hear clunking coming from the engine. I look down and see "service traction system", check engine lights, no power brakes, etc. At this point I cruise to the shoulder and wait for a tow truck.
The car was towed back to Mountain View Chevrolet and I waited for the results. By Thursday, they were able to confirm that it was an issue with the valve guide but also said that I have cylinder wall damage. I was asked to come in this morning (2/10/18) to have a look. Here are some pictures taken of the heads/cylinders.
The dealer is saying that the valve guide was an issue but is not what led to the blown engine. The blue flashlight in the pictures belongs to the service manager who is pointing out the liquid in the cylinder being the cause of the damage. I should state now this is all foreign to me (I love cars but don't know the first thing about fixing an engine). I am being told that I need a new engine and was quoted at $17k with a credit for the $5k I already paid. I figured here is a better place than any to get more opinions.
I'd call ahp straight up. Not for dealer or warranty work but if you're gonna pay for it, have the best do it.
I would separately try and get at at least some of the $5k back.
I was talking with Kohle last week about getting the heads fixed so I will be calling on Monday to get his advice too. Am I crazy to spend $17k on another LS7? Are new engines sold by GM still prone to the same heads/valve guide problems found in earlier models?
Looks like the rocker pulverized a Ti intake valve into the cylinder. It also looks like the lassh caps are missing on all the intake valves. They've all been pulverized. Straight up incompetence...dealer owes you a motor. Cut and dry.
I was talking with Kohle last week about getting the heads fixed so I will be calling on Monday to get his advice too. Am I crazy to spend $17k on another LS7? Are new engines sold by GM still prone to the same heads/valve guide problems found in earlier models?
Yes, they are...but your failure was incompetence. The mechanic didn't reinstall the lash caps on your Ti intakes.
Yes, they are...but your failure was incompetence. The mechanic didn't reinstall the lash caps on your Ti intakes.
Is there any way to prove this? Probably a dumb question, but can you point out which picture(s) you're able to spot this? I will definitely bring this up next week when I talk to the dealer.
Is there any way to prove this? Probably a dumb question, but can you point out which picture(s) you're able to spot this? I will definitely bring this up next week when I talk to the dealer.
Seriously, thank you for your help.
The picture with the two cylinder heads side by side showing the valve stems and springs. Every one of your intake valves were ready to drop. I PM'd Kohle at AHP a link to this thread...he can most certainly be a credible expert witness for you. That picture is worth a thousand words...
Looks like the rocker pulverized a Ti intake valve into the cylinder. It also looks like the lassh caps are missing on all the intake valves. They've all been pulverized. Straight up incompetence...dealer owes you a motor. Cut and dry.
Show those pictures to 6 different cylinder head shops and all 6 will tell you the same thing. In fact I recommend you do just that. Get a statement from multiple head experts and present all of them to the dealer.
Incompetence during assembly, “missing lash caps” on the titanium intake valves caused the valve failures, and one valve dropped destroying the engine.
Everything in the motor is now suspect. Block, crank, rods, cam, lifters etc.
Don’t settle for a rebuild, dealer owes you a new motor installed with no out of pocket expense to you.
How many miles have you put on the car since picking it up? Probably a thousand or less?
Probably around 300 miles if not less. After the car was "fixed", my dad picked it up and had it sitting in his garage for about a week until I was able to pick it up (12 miles).
I picked it up and drove it down to Irvine (about 45 miles one way) for work the week of the 28th (my commute to work is only 2 miles one way) and back to Rancho Cucamonga that Friday (2/2/18). Driving back to Irvine on 2/4/18 is when the engine gave at about the halfway point.
Show those pictures to 6 different cylinder head shops and all 6 will tell you the same thing. In fact I recommend you do just that. Get a statement from multiple head experts and present all of them to the dealer.
Incompetence during assembly, “missing lash caps” on the titanium intake valves caused the valve failures, and one valve dropped destroying the engine.
Everything in the motor is now suspect. Block, crank, rods, cam, lifters etc.
Don’t settle for a rebuild, dealer owes you a new motor installed with no out of pocket expense to you.
That is a great idea, I'm going to talk to Kohle on Monday and present this to the dealer. I'll reach out to a few other shops (any suggestions) and see what they say.
Another thing the dealer pointed out was that the cylinders were no longer honed which caused oil to leak into the cylinders. They're acknowledging that the machine shop improperly repaired the heads but insist that the engine failure was due to this cylinder honing problem. I just can't see how these two things would be unrelated
Were these supposed to be stock heads?
The springs are dual not beehive OEM did they tell you that OEM parts were not being supplied?
DH
I thought they were. I bought the car used over a year ago (I want to say September 2016). Never heard any valve train noise that caused concern until the night I recorded the video in my original post.
Edit: Then again, I'm not sure if the machine shop they used included these dual springs as part of their "fix". I believe the vehicle was 100% stock when I bought it and I had never modified anything.
Even if the motor had no oil and wore the cross hatching off, the result would not be what happened. A seized motor, spun bearing(s), broken rings maybe. But not the broken valve which is, iirc, what likely scored the wall.
I will say that it is odd that there is no crosshatching left (If that's even true) but again, that isn't why the motor failed.
And nd even if it was a problem, it could have ran for years like that. But it obviously won't run for years (or even 300 miles) without the caps.
02-10-2018, 04:35 PM
Blown LS7 - Need advice *long post*
