2015 Race Red Z/28 9700631 Gets a New Heart

[The_Raging_Bull]

This thread covers my adventure over the last 4 weeks. I wanted to document what happened to me as I pulled out my Z/28 to take it to the shop at the Chevy house here in Broken Arrow. So, we had seen a small “dribble” of oil under our Z/28 after it was pulled it out, consequently we were taking the Z to Jim Norton Chevy in Broken Arrow to fix whatever was the issue, since we have a full GMPP 7-year 70,000-mile warranty.




The car was bone stock. This was just the 3rd time we’d taken the Z out of the garage this year; due to an illness I was diagnosed with in May (not COVID 19) , the care of which has been like a part-time job…but I digress.

After checking the oil in the dry sump >a habit -> it’s checked to make sure its full before every drive <- and it was full. I started the Z and slowly backed out. As I turned it to get on our subdivision street, there was a weird sliding noise - like none I've ever heard before, and suddenly the car was blowing bluish (oil) smoke out of the left tailpipe. I turned off the engine immediately.
After calling Norton; I got a tow to the dealership with a truck which lifted the front end up (by lifting the front wheels), instead of a rollback. After it was turned off it was pushed to move it into the correct tow position, as the engine was never restarted after the event. We got to Norton with no what damage whatsoever.

However, we noticed at that time there was a splatter of oil on the street, and the dry sump looked like it had “burped” a little oil from the top. There was minor oil dribbled down the sump container like some oil had come out. (none on the hood). I followed the truck for the 1.1 mile tow to Jim Norton Chevy here in Broken Arrow OK. We got the Z to their lot and Norton took over. After telling the service advisor the same story I told you, and showing him the “oil dribble” I’ve shown you I left as we waited for GM/Chevy to send an inspector. I gave them all my oil change records, as the engines oil had been changed regularly by a mechanic, who BTW is an officer in the Tulsa Vette Set…so it was always done correctly.

In the initial inspection by Norton’s best Corvette mechanic, he found a small crack on the LS7 block on cylinder 7 > about 3" long< wall running from 4 o’clock to 10 o’clock. Its visible in the picture, if you blow it up, the link is to a hi res picture in my dropbox. GM/Chevy came two days later, and after pulling the left side heads off the engine – where they found the heads were perfectly clean and oiled as it should have been with proper maintenance, and that all valves were intact > so it was NOT a case of a dropped valve. BTW it did not sound like a mechanical crunch or metal breaking..it was a weird sliding noise.



Two days later GMPP told Norton that the engine had suffered a cracked block, their comment it was a defect in my block casting when it was made. It seems to be the singular defect in all of the LS7 blocks made. Consequently GMPP authorized the replacement of the engine. The bill shows the oil cooler and several other pricey parts were replaced, along with several hoses as the engine was replaced. The new engine was built by Harvey Turner.



Heres a pic of the LS7 just prior to install of the new engine, with the old LS7 in the background. The mechanic cleaned the engine bay with spray washer, but either I'll clean it perfectly or I'll have it done professionally (steam cleaned) or the new owner before delivery..if it sells.



Everyone will ask, so I’ll publish it, the total billed charge was ~$19,490 and change, with me paying a $100 deductible.

In a separate thread, I’m listing the car for sale. The buyer will get all documentation along with the remainder of the warranty that expires in Feb/March 2023, as well as a Z/28 with 7406 miles, that only has 5 miles on the engine as of the post date today. Our plans are to break-in the engine using the same break-in as I did on the original engine, 1500 miles without a shift above 4000 rpm; and if it sells to give the new owner that option.

[2SSRS@Gen5diy]

Let us know what you want for the car.

[The_Raging_Bull]

Originally Posted by 2SSRS@Gen5diy

Let us know what you want for the car.

PM sent

[Biergut]

What a bizarre thing. Thank goodness you had that warranty. Whew!

And ... let's hope this IS the only incidence!

[ariZona28]

Man, that sucks a$$! Combine that with a health issue and it's a double gut-punch. Financially it turned out OK but I'm sure psychologically it leaves a scar. Hate to see you get rid of such a beautiful machine as the result of a bizarre defect but you have to do what needs to be done.
I'm sure I'm not the only Z guy saying "oh fu%k, something else to worry about. Guess we need to place this item into the quirky Z/28 notes and pray it doesn't happen. I'm learning that these cars are not for the faint of heart or light of wallet. After wandering out to the garage and staring at mine a bit there's no doubt about it, I'm in it for the long haul. Never say never but I'll fix/pay for whatever breaks. The spell it has cast on me is too strong.

[delphigto]

Could you pm me price also

[mikeman]

Since the block is made out of aluminum alloy, isn't there a way to weld cracks like that?

[The_Raging_Bull]

Originally Posted by mikeman

Since the block is made out of aluminum alloy, isn't there a way to weld cracks like that?

There would be a way if you DIDN'T have a warranty, but when you do...you get a new engine right? That's why I bought the warranty.

I'm sure GM/Chevy is doing a tear down of the block to ascertain exactly what happened.

[mikeman]

Originally Posted by The_Raging_Bull

There would be a way if you DIDN'T have a warranty, but when you do...you get a new engine right? That's why I bought the warranty.

I'm sure GM/Chevy is doing a tear down of the block to ascertain exactly what happened.

Yeah, I guess that makes sense. However, since the Z28 is kind of a collectors item or a future collectible if you will, someone could of welded up the block and kept it "numbers matching".

Since you're selling it anyway, I realize this probably doesn't matter or maybe that's the reason why you're selling it now. I don't know. The only thing I'm confused about is that you're saying it's the lowest mile Z28 in existence when the car actually had 7400+ miles with the old engine.

Of course, all of this doesn't matter now because it's a mint driver's car with a brand new engine. The pressure of keeping the miles low on the original engine for collectibility had been eliminated. As many will say, these cars are made for driving/racing not sitting in a garage awaiting a future Barrett Jackson auction in 40 years.

[ariZona28]

It would be interesting to do a repair (if possible) and then put it on an engine dyno for evaluation. I'm curious if this is a high stress area.

[The_Raging_Bull]

Originally Posted by mikeman

Yeah, I guess that makes sense. However, since the Z28 is kind of a collectors item or a future collectible if you will, someone could of welded up the block and kept it "numbers matching".

Since you're selling it anyway, I realize this probably doesn't matter or maybe that's the reason why you're selling it now. I don't know. The only thing I'm confused about is that you're saying it's the lowest mile Z28 in existence when the car actually had 7400+ miles with the old engine.

Of course, all of this doesn't matter now because it's a mint driver's car with a brand new engine. The pressure of keeping the miles low on the original engine for collectibility had been eliminated. As many will say, these cars are made for driving/racing not sitting in a garage awaiting a future Barrett Jackson auction in 40 years.

Mike you'd note I said it had the fewest miles on the LS7 not the lowest milage Z/28...

[mikeman]

Originally Posted by The_Raging_Bull

Mike you'd note I said it had the fewest miles on the LS7 not the lowest milage Z/28...

No problem. Whoever buys it will be getting a beautiful car that's for sure.

[Mark_Z28]

Larry, read through your initial post, and the info regarding the cracked block(GM saying it was a singular defect doesn't leave me at ease even my own car)

Where exactly is the crack? Can you give any insight into if the car was started regularly or possibly over-oiled.

[The_Raging_Bull]

Originally Posted by Mark_Z28

Larry, read through your initial post, and the info regarding the cracked block(GM saying it was a singular defect doesn't leave me at ease even my own car)

Where exactly is the crack? Can you give any insight into if the car was started regularly or possibly over-oiled.

Look at the posted pic, if needed download it, its high res, the reason I put that picture (and all of the cars pics) in from my dropbox account was so any of my pics can be downloaded in high resolution to look at in detail. So look at the pic in ms-paint and zoom in, or paintbrush if you're a Mac guy like me. Zooming in is your friend. If you like I'll PM a link to download the full size pic, just ask.

There's a crack on the block wall running from 4 o'clock to 10 o'clock. The crack is apparent from oil seepage along the crack-> look carefully, as I too at first couldn't see it w/o zooming in on the picture.

The oil was full, everything copaceptic when I started.Before I drove the car- every time...the oil was checked, typically the night before. Every time the car came home I made sure the oil level was OK.The morning of the failure it started just like normal, there was no issue until I backed it on the street. The failure was evident when it spewed bluish oily smoke out of the river side tailpipe briefly, as the minute it happened, I killed the car by turning the key off.

Thanks to COVID19 It was only driven 3 times in 2020! One of those drives was to take it over to the car wash after the engine went in (that was my five miles on the engine), Jim Nortons Corvette tech also took it for a drive after the work was finished...so I suppose it might be actually ten miles. I need to look at the milage when I went in and left.

The car was not "over-oiled", it was checked each time was driven to the dipstick level in the dry sump. As I said I've got a Z06 with an LS7 too, and I treat it the same way, it sits at 12,400 miles after 11 years. I'm a bit anal about maintenance, each car had the oil changed once a year since I've had them..as I never put 3000 miles a year on either the Z06 or Z/28.

On the subject of your unease, I'm pretty sure GM x-rays the block looking for flaws. There are standards for looking for defect in QC; I was a roll-coat engineer at Alcoa; so I know some of the tests metallurgists use in large aluminum parts. On sample size, I'm guessing that 15000 to 18000 engines were built (I'm guessing) .. so 10000 to 12000 between 2006 and 2013 in corvettes, '14 to '15 had 1801 in our Z/28's; and then ?XX? how many into the crate engines and blocks? Given that -> a singular failure says its higher defect rate exceeds 6 sigma (3 defects per 1,000,000), so I'll bet they crawled all over the engine with a 6 sigma black belt...

All I heard was the comment that GM/Chevy said it appeared to be a singular defect; they'll never tell us the teardown results.