LT6 engine failures/problems
Racer
Joined: Aug 2024
Posts: 331
Likes: 205
From: Washington Crossing, PA
Not True , i have been a pro tech for 36 years, There are some very good technicians out there if you do some homework. In the hands of a pro it will be just the same if not better than it rolled off the showroom. I found little things on my z06 that were missed from the factory, a wire loom here and there, little things. Take it in, have a new engine installed and that is that. It is a race engine, stuff comes apart sometimes. We are spinning these engines to the moon. The engine is incredible.
Pro
Joined: Jan 2020
Posts: 562
Likes: 521
I'm stressing this very situation right now as I believe my Z will need to have the engine dropped to replace/repair the oil leak coming from around the timing chain cover. Where I live there hasn't been any repairs such as this performed yet. Even at MacMulkin they haven't done it yet either which really surprised me. I have found a dealership very close to me that does have a good certified vette technician there. I have met him and chatted with him and he seems VERY knowledgeable. So, my precious toy will be put in his hopefully very capable hands for this challenging job. I don't have a lot of options so I'll have to say a few extra hail Marrys and hope for the best.
4th Gear
Joined: Oct 2024
Posts: 4
Likes: 0
Hey folks, just wanna start my own lil mini thread in here for my own progress.
Just bought a used '24 C8 Z06 from LaFontaine Chevrolet group in Michigan,CERTIFIED and all, to me in South Florida.
Upon receiving the car, on turn on, I've noticed a rather loud tapping noise. I know this is usually injectors or so, but this was beyond loud, way louder than the engine and would receive comments on the streets.
I'm not sure how this passed GM-used certification, but it unfortunately did. Fortunately, it is under warranty. I've taken it to the service department where I was told this is a bulletin issue, and while not mechanically damaging to the motor, it is rather annoying in my case as it's one of the loudest.
Besides some other minor issues such as dashboard rattling/whizzing, the car drives great.
I've taken the vehicle to service on Friday morning, was told it would be potentially out for two weeks +
What upsets me is this was a used vehicle that passed the gm certification process. What should have been fixed during this certification process now falls onto me, and I'm out of a car I'm paying, for two weeks. Not a great start honestly.
Just bought a used '24 C8 Z06 from LaFontaine Chevrolet group in Michigan,CERTIFIED and all, to me in South Florida.
Upon receiving the car, on turn on, I've noticed a rather loud tapping noise. I know this is usually injectors or so, but this was beyond loud, way louder than the engine and would receive comments on the streets.
I'm not sure how this passed GM-used certification, but it unfortunately did. Fortunately, it is under warranty. I've taken it to the service department where I was told this is a bulletin issue, and while not mechanically damaging to the motor, it is rather annoying in my case as it's one of the loudest.
Besides some other minor issues such as dashboard rattling/whizzing, the car drives great.
I've taken the vehicle to service on Friday morning, was told it would be potentially out for two weeks +
What upsets me is this was a used vehicle that passed the gm certification process. What should have been fixed during this certification process now falls onto me, and I'm out of a car I'm paying, for two weeks. Not a great start honestly.
Intermediate
Joined: Dec 2023
Posts: 46
Likes: 44
It is a solid lifter race engine, they make mechanical noise and is normal, if it has a consistent light tappet sound coming from both sides this is the way it should be, You might notice it is louder when cold and this is also normal.
Intermediate
Joined: Dec 2023
Posts: 46
Likes: 44
There have a few cases where the clearance was looser than spec and that will cause a louder than normal tap sound, But it will never be silent and will always have a rattle sound at idle. What you are hearing is the gap between the cam and the follower making noise when they open and close. In a hydraulic lifter engine there is oil pressure and a spring inside the lifter that takes up this space making for a silent valve train, however this design is rpm limited. For high rpm the design on the lt6 is superior.
4th Gear
Joined: Oct 2024
Posts: 4
Likes: 0
However, when its a sound that only gets louder with the car warming up, and does not disappear after ample warm up time / speeding, stays continuous on throttle despite RPMs (not injectors), it's cause for checkup. I wish it was just a light tapping noise. But this, as mentioned, is louder than the car itself at idle + only on the left driver's side.
That paired with that I've been around these Z06s, and have never heard something like this, justifies it going in.
Intermediate
Joined: Dec 2023
Posts: 46
Likes: 44
Opposite here. I've driven these style of cars down here in Miami pretty often, so I know that "mechanical noises" is pretty usual for complex, larger engines.
However, when its a sound that only gets louder with the car warming up, and does not disappear after ample warm up time / speeding, stays continuous on throttle despite RPMs (not injectors), it's cause for checkup. I wish it was just a light tapping noise. But this, as mentioned, is louder than the car itself at idle + only on the left driver's side.
That paired with that I've been around these Z06s, and have never heard something like this, justifies it going in.
However, when its a sound that only gets louder with the car warming up, and does not disappear after ample warm up time / speeding, stays continuous on throttle despite RPMs (not injectors), it's cause for checkup. I wish it was just a light tapping noise. But this, as mentioned, is louder than the car itself at idle + only on the left driver's side.
That paired with that I've been around these Z06s, and have never heard something like this, justifies it going in.
4th Gear
Joined: Oct 2024
Posts: 4
Likes: 0
Engine builder is Dale Sherry.
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Pro
Joined: Jan 2020
Posts: 562
Likes: 521
Well, I got lucky with the possibility of the dreaded timing chain cover oil leak. I don't have an oil leak, I have a leak coming from the transmission filter housing seal I guess. I thought it didn't smell like oil!! Anywho, no need to drop the engine, it's all underneath work and the parts are on order. Bad part of my visit was that I need to buy a new tire as my left rear has 2 nails in it, one being too close to the side wall and is unrepairable. Guess I'll need to buy a new tire. Only 5k miles on it so a new one shouldn't be much different in tread height.
Thread Starter
Safety Car
Joined: Jun 2008
Posts: 3,806
Likes: 5,869
The LT6 engine, featured in the Corvette Z06, is generally praised for its high-performance capabilities. However, like many high-performance engines, it has faced some issues. Notably, early production models have reported problems such as engine failures due to oil system issues or crankshaft bearing failures, sometimes attributed to manufacturing defects. These failures can cause costly repairs or even full engine replacements. GM has worked to address these problems in subsequent production runs, but some owners have expressed concerns about the engine’s long-term durability under intense use.
4th Gear
Joined: Oct 2024
Posts: 4
Likes: 0
Hey folks, just wanna start my own lil mini thread in here for my own progress.
Just bought a used '24 C8 Z06 from LaFontaine Chevrolet group in Michigan,CERTIFIED and all, to me in South Florida.
Upon receiving the car, on turn on, I've noticed a rather loud tapping noise. I know this is usually injectors or so, but this was beyond loud, way louder than the engine and would receive comments on the streets.
I'm not sure how this passed GM-used certification, but it unfortunately did. Fortunately, it is under warranty. I've taken it to the service department where I was told this is a bulletin issue, and while not mechanically damaging to the motor, it is rather annoying in my case as it's one of the loudest.
Besides some other minor issues such as dashboard rattling/whizzing, the car drives great.
I've taken the vehicle to service on Friday morning, was told it would be potentially out for two weeks +
What upsets me is this was a used vehicle that passed the gm certification process. What should have been fixed during this certification process now falls onto me, and I'm out of a car I'm paying, for two weeks. Not a great start honestly.
Just bought a used '24 C8 Z06 from LaFontaine Chevrolet group in Michigan,CERTIFIED and all, to me in South Florida.
Upon receiving the car, on turn on, I've noticed a rather loud tapping noise. I know this is usually injectors or so, but this was beyond loud, way louder than the engine and would receive comments on the streets.
I'm not sure how this passed GM-used certification, but it unfortunately did. Fortunately, it is under warranty. I've taken it to the service department where I was told this is a bulletin issue, and while not mechanically damaging to the motor, it is rather annoying in my case as it's one of the loudest.
Besides some other minor issues such as dashboard rattling/whizzing, the car drives great.
I've taken the vehicle to service on Friday morning, was told it would be potentially out for two weeks +
What upsets me is this was a used vehicle that passed the gm certification process. What should have been fixed during this certification process now falls onto me, and I'm out of a car I'm paying, for two weeks. Not a great start honestly.
They mentioned to order the parts it would take another week, which then it would take another week to have the car repaired.
As for the dashboard whizzing noise, which is audible on a video I've recorded going at 60mph even, they stated the repair to reseat/refit the dashboard for it is not authorized by GM, and will not be done.
So far this vehicle has been a nightmare going in with only 3 days of actual ownership. The car's performance, and looks when turned off, is nothing but amazing. However, the quality control of a "certified" 2024 pre-owned vehicle is abysmal, and the customer service of GM is non existent. Very disappointed.
Burning Brakes
Joined: Nov 2004
Posts: 898
Likes: 149
From: SE NY and SE FL
Yeah, no kidding. Even people that write for a living don’t write like that. The disturbing thing is that it appears, at least to me, that the ones that would seem to benefit most in using AI / Bots to building thread responses, driving traffic to the site are the owners, Internet brands. I can certainly be wrong and would be happy to hear other thoughts.
Drifting
Joined: Jun 2015
Posts: 1,574
Likes: 554
When GM decided to design the LT5 they ran into the same vibration issues but through some pretty amazing testing were able to determine that a large portion of the vibration was not from the crank and pistons at all, its was the AIR moving inside the crankcase. Thus the patented design of using 4 separate crankcase compartments each with its own evacuation pump. This was the breakthrough that allowed GM to do what Ferrari and Ford could not. 5.5liters of flat plane crank that can rev to 9000 rpm and generate over 700 HP. There are some great SAE papers published on the LT5 design and the high caliber engineering that allowed it to happen. GM has much to be proud of in this engine and the competition will not duplicate it.
Pro
Joined: Feb 2021
Posts: 690
Likes: 177
The Voodoo engine has a different layout. Ferrari has used a flat plane crank in every V8 even going back to the first 308's and they were successful. The larger piston is relative, it was necessary to have a short stroke for the given displacement which is paramount for balancing.
Drifting
Joined: Jan 2023
Posts: 1,759
Likes: 1,494
2024 C8 of the Year Winner - Unmodified
The Voodoo engine has a different layout. Ferrari has used a flat plane crank in every V8 even going back to the first 308's and they were successful. The larger piston is relative, it was necessary to have a short stroke for the given displacement which is paramount for balancing.
Burning Brakes
Joined: Jul 2024
Posts: 785
Likes: 471
Burning Brakes
Joined: Dec 2006
Posts: 1,146
Likes: 508
Well, I got lucky with the possibility of the dreaded timing chain cover oil leak. I don't have an oil leak, I have a leak coming from the transmission filter housing seal I guess. I thought it didn't smell like oil!! Anywho, no need to drop the engine, it's all underneath work and the parts are on order. Bad part of my visit was that I need to buy a new tire as my left rear has 2 nails in it, one being too close to the side wall and is unrepairable. Guess I'll need to buy a new tire. Only 5k miles on it so a new one shouldn't be much different in tread height.
And why would they diagnose it as a timing chain cover leak before they even look at it?
Last edited by jswatek; Oct 31, 2024 at 10:11 AM.