Why everyone is scared of LS7’s 

It knew you weren’t wearing new balances and rejected your ownership

It’s about $2,500 to $3,000 parts and labor to have this issue fixed before you drop a valve. Every LS7 should have the valves updated.

As a retired GM dealer head tech: (ASE Master w/L1 cert.) 40+ years in the buss. and 30+ in a GM dealer I can honestly tell you that GM is the KING at gaslighting!!! Generally when you call about something that will be VERY COSTLY they start to deflect. It's like the old saying: ( If their lips are moving they are lying) Retired 6 yrs now and don't miss one damn thing about dealing with people like that!!!

It wasn't certain years or a bad batch, every LS7 across all the years is suspect!

Greetings from New Zealand. Thanks for the video and condolences on the blown motor. I have an '07 Z06 which I purchased 2 1/2 years ago. Went for a test drive with the then owner and I just had to own the car. At the time it had around 27,000 miles on it and in the interim I did some 'due diligence' on the LS7 head issue and negotiated a better purchase price. I sent the car to a performance engine shop for checking. The 'wiggle' test was hopeless, so made the call.... The Intake valve to valve guide clearance was top limit and the exhaust was 50% OVER top limit. In addition, one of the trunnion (rocker) bearings was in the process of collapsing. Thank god we checked it because the wife would NOT have been happy. Because I'm an 'old fart' of 70, and will never drive this to it's potential, we fitted 1/4" longer valve guides (better valve stem support) and stainless valves. Still have the Titanium valves if the next owner wants to retro fit. All the best with the 'fix'.

Good to hear that you weren’t inside the cylinder during failure. Always risky hanging out inside the cylinders!

been in a big name OEM and race automotive engine testing lab and the first engine that blew under my watch, blew a rod out the side from a dropped valve was an LS7 back in 2005.

There will not be any contaminates in the oil, these valves fail from the fusion weld of the exhaust valves. The valves in the LS7 are hollow and the actual valve is friction welded to the stem, this is the failure point and there is really no way to predict the failure.

Vengeance Corvette in Atlanta had a special running that replaced the heads with stage two cnc ported heads with bronze guides and I chose Manley severe duty stainless valves. I think the total bill was about $3500.00. No matter how many miles you have on an engine, get the heads changed out and be done. Anyone who has driven an LS7 would not be happy with an LS3.

As a heavy equipment technician for a fleet with a lot of experience analysing oil analysis I can tell you it is one useful diagnostic tool. I've used many oil sample analyses to solidify a diagnosis or even prevent a failure occurring. But with that not every failure is detectable or preventable even with the best of maintenance. Some defects can create stress points that don't show signs until it is absolutely too late. For an example most Symptoms of EGR cooler failures are detectable with an increase of potassium and sodium in engine oils, but I've seen clean oil samples where the cooler suddenly dumps coolant into the engine hydrolocking it. Data is important, but you seem to forget one thing, variables and endless and can change or even hinder data useless.

From what I learned. The centerline of the guide and the centerline of the valve seat are not in line. A brand new head was measured before being installed, and that is where this conclusion came from. The bare head was a replacement under warranty, and the associated parts were loose. The machine shop had a pristine head to check tolerances and found things out of alignment. 2007 Z06, heads fixed, and Crower shaft rockers installed.

I love the way these ls7’s chop with a big cam at Idle!

Hey man, I don’t think you’d see anything in the oil at all before this failure as it’s not a progressive failure. Most likely the valve stem’s non-conformance to the design tolerances caused the valve head to be subjected to a small elastic strain every time it closed as the head was closing on one side of the seat first. This would cause high cycle fatigue in the neck of the valve, causing an almost instantaneous failure as it finally fractures.

This is why I went with the c6 grand sport. More or less the same price without the fear of exploding a $15k engine.

If you haven't decided already, I vote stroker ls3 with mild cam. They're great.

This is the first video I've seen of yours and instantly subscribed. My jaw dropped when I saw behind the throttle body.

I currently own a 2015 Z 28 with 35,000 miles on it and have always debated on this issue I’m gonna pull the trigger and get the heads fixed and of course while it’s open upgrade the cam and have headers and high flow cats install the same time I just think it’s peace of mind the car it’s an absolute joy to drive and I love it.

Best video I've seen on the LS7 valve drop issue. Pro video quality and editing as well. Subscribed.

I'd have to say that I would certainly agree with your reasoning on being comfortable with this engine prior to it's failure. Just goes to show how much of a beating a valve can take when it's in a situation that can lead to failure. I'd put an LS7 back in it, lightly modified in the manner of your choice as compared to what you had.

It's just my theory, but it's based on an experience I had with an early 5.7 V-8 that suffered from valve guide problems at moderately low mileage (60,000 mi.). The LS-7 came equipped with a lot of performance upgrades, with the exception of one thing, roller tipped rockers. GM made the leap to roller camshafts in the late eighties but neglected the one component that enabled the cam to do it's job without causing damage elsewhere. Roller cams have steep or short duration valve opening event ramps, which accelerate the rockers from static to in motion in fractions of a second. It is my opinion based on my experience that this instantaneous motion causes the rocker to not only push the valve stem downward, but additionally, it tends to pull the valve stem up toward the fulcrum of the rocker due to friction between the rocker and stem end. This creates excessive side loading in the guide, causing premature wear and eventual guide failure. In my case, it showed itself by excessive oil consumption via the guides, but with continued use it possibly could have led to catastrophic failure. It eventually led to a complete engine replacement that GM footed the bill for.

Got my C6Z06 LS7 with bad bearings and still ongoing rebuild... Lots of headaches about new bearing clearances and parts that are on backorder by GM though... I'm quite interested about the oncoming project of yours and surprised your Oil analysis did not help spot any problem beforehand.

But hey GM says it’s not an issue so your engine is 100% fine

This is a relatively exotic engine, materials wise. I wouldn’t expect it to go 100k mi w/o extra maintenance. The valves are Titanium and need to be monitored for elongation. When lash shows the valve has stretched 0.010”, throw them away and put new in. Don’t expect the Titanium con rods to last forever either.

Based on the known probability of occurrence of the failure event described. I suppose a new owner of a used LS7 should simply weigh whether setting a corrected set of heads on the short block, or simply driving it as is.

6K gets you peace of mind. When buying one of these just factor that into the cost and have the valves replaced is my 2cents

Brutal and another reason why I got my heads fixed prior to really driving mine. Sub'd to see what you guys end up doing!

Thank you for your video. Very well done. I appreciate your detailed information. I'll be applying the lessons you learned to my car shortly.

As a machinist, you just have to understand the materials, it make perfect sense to why this happened, Titanium has a coating over the material when the coating wears off then Titanium will gaul and stick, so if the valve coating is wearing away, then most likely the Connecting Rod Coating is doing the same, Bronze will not gual Titanium Valves, going to a Stainless Steel Valve or a Bronze Valve Guide will prevent this, Its time to start looking at the connecting rods before you have a major failure.

We had a c6 zo6 at the shop about a year ago, the way the engine failed seemed to be similar. Total destruction, you could look through one side of the block through the other, it had holes on both sides. The only mods were an intake manifold and exhaust

If you have a LS7, do the upgrades to fix any potential issues. As far as what engine to replace it with depends on what you mainly use the car for. Sounds like you love track. So go with what you is best for you.

Sucks to have this happen, but the good news is it gained my sub. Looking forward to seeing how you deal with this unfortunate experience.

Really love how your channel is narrated and documented. As someone that has worked on a few of these cars (c6zs specifically). They are insanely phenomenal cars that respond well to a cam and ported heads. I would do another stock short block or something similar as they are hard to come by and have the heads repaired and ported. BES Racing engines in ST Leon, Indiana has an amazing LS7 program that is world renowned

I've never see more cars blow up at HPDE days than the Z06.

It seems to me that you have direct evidence from Blackstone that this wasn't a wear issue. Or at least, the amount of wear that occurred prior to failure was slow and steady enough that it didn't show up as abnormal. This was my biggest fear that prevented me from buying a C6 Z06 - the valve issue is not wear related. It may be a problem with the design where the components can be within the manufacturing specs and still have insufficient strength to stay together over time. Fatigue failure rather than wear failure. And my research indicated that some of the aftermarket fixes might not be reliable either. Failure can happen at any time and there's no perfectly reliable indicator. This is similar to why I sold my GT350. I know some owners never have a problem, but the risk wasn't worth it to me. I would consider an LS3 or some other version of the LS as a replacement to avoid recurrence.

Valve failure will never show up in the oil. I’m pretty positive the ls7 have hollow stemmed valves. They are super light weight, but in return they tend to be brittle and unable to stretch, so there is no wear evidence, they just snap eventually.

This is the first of your videos I’ve ever watched. When you inserted the clip about the bird’s gizzard I fckn lost it man😂 had to leave a like

The exhaust valve is a two piece valve and they brake off where they’re fused together.

Having a motor let go sucks and I feel for you, but: a Small Block Chevy that makes 500hp and runs for 15 years/70k miles (including track use) is still impressive. Not ideal obviously, but no small feat. I have 30k on my 2007 Z06, stock, bought it a year ago, 4 HPDE days so far. Read all the internet stuff, decided I'm not touching a running motor, fingers crossed. This video is very informative, thank you for posting it.

Very well done. Very detailed and cogent arguement.

I bought a Grand Sport for 2 reasons, 1st was the removable top 2nd was the valve drop issues, I did want a Z06 and almost pulled the trigger on one but honestly the valve drop issues is something I could never be comfortable with driving the car wondering if the damn engine is going to blow up every time I run it hard.

My c6z got 85k miles on the clock, the oil sample looks clean and I was thinking the same... If it will drop it should have already been dropped.😢 Damn now I'll get my h/c done sooner

I have an 06 GTO LS2,I hear light clicking low rpm's always have,what about the heads on this motor,strong as a horse running wise,do tell?great info on LS7 thanks for video

Coyote swap 😂 sorry I’m a Ford guy and I had to do it. The first motor I ever blew up was a “built” 3 valve that was pro charged after a month of ownership. It lasted 4 years and after I tore it apart I found out the shop that “built” the engine just pocketed my money and threw trash parts into my engine. Lesson learned 👍

You could always check the valves by taking the valve covers off and wiggling the valves. Also its super easy to just get new valve guides installed. Also its shitty how GM never truly took care of this issue in their best corvette ever made.

There are many factors to consider in any part failure . This is one heck of an expensive failure to have gone on this long !

Asked my warranty carrier if they would approve a pre-emptive repair and they said no. They wound up paying a 23,000.00 claim. Then we started with a new 5.3 truck block, installed darton dry sleeves, properly machined and ported LS-7 heads, etc.,etc. Now I have a 440 c.i. beast that is awesome to drive on our local road courses. Many thanks to LME!

GMs had the wiggle test for YEARS in the 80s/90s it was common for GM calling for "wiggle test" while diagnosing electrical problems , wiggling the entire harness from from to back to see if a fault spike occurs.

My Corvette specialist said if you're at nearly 50k miles, your chances are lower, but not 0%. They said if you plan to track the car, you should do the heads anyway.

Would stainless valves live longer? Probably but you gain valve float & rpm

“I thought I was safe because I had stock heads and never had a problem yet so I just waited until it became one” 😅😂 OOF. That hurt the wallet.

This is a fantastic video. I made one on my channel a while back outlining the issue and offering a clear warning and suggestions. Many people criticized that warning and called me every name in the book except for "logical". I have no interest on rolling the dice...I got mine fixed and made the odds a bit better for my Z06...which I truly love.

Yikes! Definitely rethinking that LS7 swap in the GTO I was planning.

Nothing like dropping a valve for engine destruction!

Well done video. Great information. Good luck to you.

Curious if it was lean, heated the valve, valves stretched and kissed piston

After much ado, I couldn't do it, and bought a 13 LS3 GS. I can supercharge it. I wanted the steel frame.

GM....designing things to fail for service revenue is our business model. Have a nice day.

At 50K miles I dropped off my ZO6 with Katech in Detroit for a Stage 2 upgrade. I don't track the car, just some spirited street pulls from time to time. I'm at 70K now and my ZO6 is still running great. Fingers crossed the work Katech did while rebuilding the heads will ward off the dreaded valve drop.

Gm recommends 15w-50 for hard driving/track use. I wonder if this is why, to help prevent valve drop issues.

Yo why is this engineer so damn jacked? Asking for a friend

Do you think it wouldve ever happened with tvt green or a similar additive?

I had a GM service bulletin on the 6.2 heads cracking and just upgraded the heads to prevent problems. Any time you have a service bulletin, replace or fix item regardless.

make it an electric track car or a coyote swap! Or stuff the c4 ZR1 into it

Put a Coyote 5.2 Voodoo in it.

An LS7 with revised parts fixing this particular bug, that's what I'm voting for.

If you have an ls7 car don’t risk it you have a couple options you can send the heads out for a professional valve job, or buy an aftermarket set cnc ported heads, you could also send your heads to Texas speed or other head porting services to get a cnc port job and a good valve job, ls7 will make 70-100 hp more with just ported heads and a cam

Is there a certain year that this problem was taken care of? I’m in market for a c6 zo6, didn’t know if I should look for 2009 and up or only 2013 or..?

The LS7 was also noted for breaking valve springs, which allowed the valve to contact the piston. My neighbour's '06 developed a miss, luckily at slow speed a couple of blocks from home. Fortunately, the spring still kept the valve away from the piston. I replaced the broken spring with the head on the engine after a leakdown test verified the valve wasn't bent and it has worked fine for 5 years now. I did recommend replacing all of the springs, but he is cheap. lol

I wish I had seen this video earlier. Mercury Marine makes a dual overhead cam version of the LS7 that revs out to 7500 and makes great power.

I want to know more about that massive crankshaft that is featured at the end of the video. Please share some details.

how could you see something about valves or guides in the oil since the giudes are underneath a valve stem seal, so it doesn't see oil

I'm actually quite curious about this. The Z06 has Massachusetts plates, but in the video you mentioned being in Kansas? Did you move or was it originally registered out east? Super curious only because I live in RI - that's how I recognized the Mass plates so easily.

I rebuilt an LT1 from 1996 replace rebuilt everything except pistons. I put 3500 miles on it over three years with no issues. It dropped a valve on start up one day. I drove it home. Still had oil pressure to the upper part of the engine. Pulled it apart, piston was dented but not bad, had the head fixed, new valve, new guide, cleaned up surfaces and reassembled it. Started it up and had no oil pressure to the top end. You may never know what happened to cause the valve to drop. Seems odd it dropped after all that time, but no matter the milage, running any engine hard calls for routine checks / inspections. Hope you can figure out that happened, so you can avoid the issue in the future.

Mine had connecting rods rubbing. Found that with an oil sample and then an in-depth look at the oil filter media. My car had the heads “fixed” by lingenfelter when I bought it. I asked the shop to check the heads while the engine was out. Valve guide to stem wear was excessive. Lingenfelter will not stand behind their work nor would I trust them to “fix” their mistake anyway. The exhaust valve seats were already leaking too. Heads are being sent to AI in charlotte NC. Block is being fitted with Eagle forged crank, K1 conn rods, Carrillo pistons BTR stage 3 cam, new lifters, trays, &pushrods. Doing the CHE trunion upgrade to the rocker arms, Manley stainless steel exhaust valves, AI bronze guides (maybe new intake valves too). Kooks 1 7/8, 3”x pipe and McLeod clutch with bleeder. That oughtta fix it lol

I always used to hear Gwatney Chevrolet radio ads when living in central Arkansas. They are both in Jacksonville…surely must be related

Thanks for keeping it real 💯

I’m kind of new to this. Been wanting this car since hs. Now that I’m 31yrs I’m finally in a position to save up a buy one. Is this like some sort of “must fix” deal or you’ll end up blowing the engine?? And back in middle school I heard these engines were hand built

Excellent information!

I bought a 8,500 mile Z and the first thing I did was fix the problem via Lingenfelter performance. If you buy the car understand this is not an option. And honestly it’s a great first mod. Gives you a chance to upgrade the valve train , new head gaskets and CNC port the heads. My car makes 531 with no cam , just fixed heads and intake.

So is a 6.2 iron block with ls3 heads better than a 7.0l ls7? Thank you in advance

I recently bought a smedding performance ls 427 power adder long block and heard that side loading was a problem with the 11° heads so i had them put the Texas speed rollers on it and i hope i never have a problem...

But the camara still shows cyl 1 valve stem in its guide, what happened?

The valve problem was in the 2006 ZO6 and corrected by G.M. Is this true ? Thanks.

Idk 🤷‍♂️. But I got a 2006 Z71. Tahoe 5.3 with 191000 . And it’s been through some brutal winters in Ohio it’s 17 years old I keep it rust free. I know my buddy has a 2001 Silverado 2500 with a 6.0 he got 287000 miles I feel bad for you. Plus some of our work vans or GMC 2500s one of them has well over 335,000 and only thing it has asked for was a transmission but all the vehicles I just mentioned have had rough life’s. Whatever motor you do choose or are you going to make sure it’s blue print and balanced ?

So sorry, saw your post on the forum. FWIW, I bought my Z06 with only 6k miles…and the AHP pkg 4 heads actually arrived a day before my car arrived. Just sayin. Turned out several valves were at, or slightly outside GM spec (and way outside AHP spec). Would it have held? How long? Who knows? Too expensive to chance it. And yes…chance of failure obviously increases exponentially with aftermarket cams. Heck…the engine already has 1.8:1 rocker ratio. I’ll also add that with such oil temps, I use heavier oil, moreover with much higher ZDDP for added lubricity. And try to keep oil under 250f (long story). Again, sorry for your failure. I’d source another LS7 (stock cam!) and make sure the heads are refurbished. Good luck…and great video

Gm never made right on my old c6 2005 z51’s exploded rear diff that was properly maintained when the outer casing randomly cracked

What would be the most reliable LS/LT engine for engine swapping?

It’s all okay in the long run. Lots of money will make it just like new again, or even better!

Just subscribed, glad you made this video

I have a 12K LS7 and I'm terrified of what happened to you. I literally have one of the first sold 06 Z06 engines. I don't intend to ever beat on this at all but still keeps me up at night. Peace.

Sucks to watch about your issue! Did you have an expanded oil tank installed? Lot's of info online about oil pressure drop when on track with long sustained (over 2 second) high g corners. Just curious if you ever logged Oil pressure (looked at your videos but you normally had oil temp on the screen). I'll be tracking mine this summer... Looking forward to any rebuild videos!

Had this happen 2 years ago after a cam upgrade, the car ran fantastic at the dyno, after i got home and took it back out. Around 2nd or 3rd gear spirited run it just did a quick pop and smoke from the engine. About 8months later, new build : ls3 block bored out with darton sleeves, larger forged pistons, step up larger bore, replaced the one broken titanium rod, everything was fine, kept all the ls7 components ( rotating assembly etc). New set of stock ls7 heads got the entire vlave job completed, kept the titanium valves, upgraded the exhaust to ferrea ss. Tsp stage 2 cam Rocker bushing upgrades Msd intake.manifold Nick Williams TB Basically all bolt ons with extra major internal upgrades, ran 630whp at the dyno and revs to about 7500rpm. Next upgrade will be Vengeance Performance head work, upgrade fuel injectors, and id say gra few extra HP with harmonic balancer and a ported msd intake manifold. I should be able to get this monster to 670whp NA on 91 octane At the most maybe ij the future a procharger running 3lbs for thst extra 50-80hp lol not sure i can get anymore power NA after the heads / msd porting

wanted to mention this a nice video production good quality and entertaining.

I'm sorry for your loss.

great video!

Sorry for the loss. Quick question. What does the valve spring look like? Is it broken or bent with the valve??

I always considered it to be a Harmonics and heat treating issue with the valves, the guides and the out of spec tolerances across the board. When the wear surfaces of the guides starts to get out at spec enough for the valve to start having lateral play at any substantial RPM I believe after multiple high stress heat cycles it causes microfractures and cracks to run longitudinally through the valve shafts and once enough of microfractures/cracks form and becomes weak enough they become a ticking timebomb till it splits apart and drops into the piston head. I've always wondered if somebody took a pair of the remaining good valves after a valve drop to an x-ray or deep imaging center if the occurrence I speak of would be present or not.... 🤷

I know that the 1961 - 66 Buick Nailhead had side loading issues with the valves. Replacing the rocker assembly with the 53 - 60 version fixes that problem and the problem of dimpled valve stem ends as well.

You mentioned that you're in Kansas and I'm looking for a reputable tuner to take my G8 GT to around the Johnson County area, do you know of any shops you trust?

Thanks for sharing. I owned a C6Z for a couple years. I miss how special that car was, but not the interior. With the valve issue, driving that car was like dating a stripper. Amazing and insane, but in the back of your mind you always had to be aware it could go very wrong, without warning, at any time.