Hi, I don't have a Corvette, but I understand my 2006
Silverado has a version of the Corvette motor. It's with
aluminum block and heads, 310hp, and it is noisey as hell
if you ask me. The dealer tells me they can't hear
anything unusual in it, shining me on as if I'm some kind
of nut. I'm about ready to go over their head.
I hear a sound akin to someone banging a pot with a wooden
spoon, or like the ringing a big bell off in the distance.
I've listened to as many of these pickups as I can. I've
heard this noise in one other, but it was more faint, and
on the opposite bank of the block. Sometimes my engine
sounds as if its a diesel! For some reason, I can't get
any information on the chevy truck groups, it's as if all
the knowledgeable people left, and there is little to no
posting about new trucks.
In addition to this noise, I notice the serpentine
tensioner hops around alot. I don't know if that is
normal, but the crank pully runs out on its face and I know
that shouldn't be.
Can anyone give me any insight into this stuff?
Not really, but both the Corvette and your truck have an engine built by GM and
they have been building aluminum V8s since 1961. This is the first time I've
hear them called noisy.
Don't hold back, go over their heads, what do they know as a dealer.
The subject said "noisey aluminum engines" and now you think it is only two?
So now you think it is the belt tension pulley and not the engine? What does the
dealer say about the run out on the harmonic dampener? Did they think the motion
of the tension pulley was acceptable?
One thing that has happened to the Corvette LS series engine is the crank is
hollow and is filled with oil. There have been some of the retaining bolts on
the crank/dampener come loose and would cause the wobble that you speak of. It
would also have an apparent oil leak that would show up quickly in the front of
the engine. That loose dampener could create a unusual amount of belt slap and
make you tension pulley hop. It can also come off and exit through the radiator.
With the engine running and all of you fingers and clothing out of the belt path
does the belt seem to track smoothly? Does it run smooth for a while and then
seem to shutter and get noisy? With the engine off/not running can you turn the
large washer on the end of the crankshaft? If so you need to make the dealer
aware of that fact very soon.
The six aluminum engines I've owned have been very quiet and smooth so I can't
explain why yours is not other than the loose dampener that happened to some a
couple of years back.
Almost forgot, there was some piston slap some years back because of the short
piston skirt that I thought they had corrected. That would show up most of the
time when it was cold and have no effect on the belt.
OK. So you have not heard that you can hear sounds coming
from an engine with an aluminum block and heads, that
aren't heard with a cast iron block, simply because of the
nature of the difference in the metal properties? I mean I
know they don't use aluminum for bells, probably becuase it
wouldn't be the best material, but I know for sure they
wouldn't use cast iron, because it won't ring at all, even
if its made into a bell. Are you saying that a Corvette
and my truck do not use the same block?
I plan to, I really didn't like the service manager and the
response I got from him. You would think he'd know
something about these motors, but he probably is where he
is only because he's a good butt kisser.
I said "engines," hoping that someone else had heard one of
them and would reply.
I don't know what it is, or if it and the sound I hear are
What does the
The salesmen who sold it to me told me to bring it in when
I can, I haven't been able to yet.
I presume that would be after some mileage has accumulated?
Mine has done it since I got it with 40 miles on it.
No, none of that.
That loose dampener could create a unusual amount of belt
I have 2,000 miles on the rig right now, and it hasn't
seemed to have worsened, it's just that this motor gets
noiser at times, and quieter other times. It really
doesn't make any sense I know.
I'll look at this.
I know about the piston slap thing. It was talked to death
in the truck groups a couple of years ago, but haven't
heard a thing on it concerning these later models. I have
a co-worker who says his wifes Suburban, that has the same
engine as mine is very noisy too. Much louder than mine he
says. He also says he knows a tech personally, and he told
him there was nothing wrong with them, that that is just
how some of them sound. And, that they do get some
complaints about it, but they've not been able to find
Myself, having been a machinist for several years, I don't
think you can have mechanical clanging noises going on and
not have something going on thats either wearing or loose,
and will soon come apart. I've heard engines over the past
few years that you can't even tell are running they are so
quiet. Should have never heard them I guess. Another
thing that bothers me about this truck is its body lines.
If you get a chance, look at the way the new power dome
hoods fit to the fenders. Nearly all of them are out of
alignment. As if they were using bad dies, or just didn't
adjust them at final assembly. These are not the only
troubling things, and I'm wondering if GM employees didn't
get word of the huge layoffs and decide this was a year to
not care, or even go as far as sabotage. I've seen it
happen before in large manufacturing environments.
Much less likely to have a noise with the present construction and the use of
aluminum brackets and mounting points to stop the transfer of sound and
vibration as was common with the old stamped and cast iron brackets.
Actually that's incorrect and bells are most certainly made from cast iron and
cast aluminum. We had one of iron on the farm to call in the workers for dinner,
(yes, it's dinner on the farm, not lunch), when we were thrashing.
Don't know, you didn't bother to say what engine it has, very possible that it's
not the same block. Some think that if they say that it's a Corvette engine that
it could make a sale for them, did it? I've been around the plant that cast the
engine blocks since the late 40s and it would take a while to get the answer to
that question. Most people have no concept as to the number of variations there
are in the same displacement engines GM builds.
As an added variation the entire drive train for the Corvette is a solid unit.
Your truck is not. The transmission, clutch, and differential is in the back and
is connected to the bellhousing/engine by a substantial aluminum torque tube.
Your truck is not. The entire drive train is mounted in aluminum cradles on
rubber cushions. Your truck is not.
I guess I shouldn't have replied because I have never heard the sound from an
aluminum Corvette engine that you describe.
So they've not looked at it and you are building a case before they do?
Unless the compressor clutch is rattling.
Now there is some third hand information that I'd take to the bank. Much better
than the baby sitters boy friends, mothers, plumbers, landlord said........
You evidently haven't worked around a Minster, Acme Gridley, or a Wera
profilator, they all sound like they are coming apart and seldom do.
Pretty much the way with the LS1 and LS2 Corvette engines I've owned have run,
very smooth and quiet. That's before the Corsa exhaust was put on though.
You didn't notice those before you bought it? I have them put it on a lift and
look at everything before I finish the deal. In one case I waited on an ordered
1976 Corvette for months that was trash and got my deposit back and never did
buy one for another 20 years. Should have done the same thing on the '63 when it
came in but I was hot to drive another Corvette and just a bit stupid. The
quality of the '60 and '70s I hope is a thing of the past.
You have an investment in a vehicle, take the time to get it checked properly
and document it in detail. Then do it again at another dealer, and then if you
don't get any satisfaction push for arbitration quickly. GM tends not to come
out to your house and work with you until you're happy, you need to push or
they'll ignore you until you go away.
That bell is made of aluminum. One of the common ways and
simple ways to tell whether a casting is a casting of steel
or cast iron is to suspend it and rap it with a hammer.
Cast iron will ring dead, while cast still will ring.
Ok, well I can't definitively say that it is, but having
worked in manufacturing for many years, I do realize that
for simple economics sake where literally millions of
blocks are to be made that they are going to make them
generally the same, even for different applications. Any
following modification necessary for a particular
application variation would be available on any of the blocks.
I'm glad you replied. Your reply is very interesting, and
has been helpful.
They had a whole team look at it after I brought it back
within a couple of days, complaining about the noise. The
service manager scoffed at my hearing, and said he couldn't
fix something that wasn't broken, a different salesman
scoffed at my concern, and both assured me "I was the only
one who HAD EVER came in complaining about any noise in any
engine in any of these Silverados. Even while they went on
to say that aluminum will transmit more internal mehanical
noise than a cast iron block, and that if I HAD a cast iron
block, [which is apparently available in the same model
year], I would not hear anything! The "certified
technicians," [don't dare call them mechanics anymore],
weren't even as old as my grandchildren, but one, when the
honchos weren't around, said he could definately hear
something unusual, and showed quite an interest in
listening to it. He proclaimed to me that "he could
definately hear it!"...and this after everyone else denied
they could. He would not speak up when the honchos came
back, and I didn't call him on it, not wishing to embarrass
him or myself. And yes, I will build a case, as is the
wise thing to do. And yes, I will get a lemon lawyer on it
if they deny they hear it when I leave it, and yes, I will
get the word out to as many folks as possible, EVEN if I
have to create a website and submit key search words to
google to get the word out. Just as much for the
disrespect and mocking I received at the dealership for
having purchased at $34,000 truck and had the gaul to
complain about it's shoddiness.
I don't know what you are talking about here? The air
I know that this was an old inventory truck. Probably one
of the first to hit the dealer. It was on sale in May this
year for that reason, and I got a comparatively good deal
on it. However this truck could have set on the lots, and
been moved from lot to lot over the course of 10 months or
so before they sold it, never being driven over 47 miles
total in that time. Is it possible short drives, perhaps
heavy footed, and perhaps heated by car jockies, or long
periods of bearings or other mechanics sitting stale in one
position for extended periods of time could have flattened
some round that would not have been flattened with daily use?
I completely understand what you are saying, but why say
it? Not everyone is completely stupid. I don't see what
interest my co-worker might have in protecting GM unless he
were major stock holder, and I think it can safely be said
he's probably not.
Yes I have, but you are right, they do do a lot of clanging
and banging, but you know as well as I do that these noises
are from conditions made when factoring in the movement and
machining of external components added to the machine, and
so they would not exist without that addition. I did a
thorough rebuild on a worn out six, or an eight, [can't
remember its been so long ago], spindle Acme Gridley that
wouldn't hold tolerance no matter what you did, and put it
back together again.
I don't know what Corsa is, but I did ask the salesman as I
test drove the truck if they put cheap mufflers on them.
You could hear the rumble, he said, "hell no, do you
realize every emissions component all the way to the tip of
the exhaust pipe on this truck is guaranteed 100% for eight
years?!" I realized then that though he didn't say so,
that people who bought these apparently just wanted others
in the next lane to know they had V8's in them.
No, I didn't notice that when I bought it, does that make
it my problem?
I have them put it on a lift and
Few persons I expect, are expert on what to look for, nor
expectant of what could be "not right" on a new vehicle,
and I would think you'd probably know that. You must know
GM knows it.
In one case I waited on an ordered
and got my deposit back and never did
I feel similar on my decision to have bought this truck.
What were wrong with the Corvettes?
You mean when you could actually lean up against body sheet
metal on a car and not dent it? Or expect that the paint
would stay on nearly forever? Or that they'd start in -20
degree weather without block heaters?
I believe you are right, and I will do so. When you say
document it in detail, are you speaking of sort of keeping
a diary of your experience both with the vehicle and dealer
response? I've done that. I only wish I could get them to
document the fact that I brought it in and how they responded.
In the seventies, I bought my last "new" Chevrolet prior to
this one. It also had an aluminum block, but cast iron
head. At that time, the warranty was 10,000 or one year.
At 10,500 the second motor threw a piston and rod into the
pan and they weren't going to replace that engine with a
third. I dogged them, with a hand written letter to the
top and they did.
Let me just recap a few things.
1. Cast aluminum engines are not more prone to be noisy, or be heard easier, I
could care less about what the dealer told you.
2. It is not true that an aluminum engine would be easier to hear a noise than
if it was an iron block, pure poppycock.
3. Cast steel, cast iron, cast aluminum, cast brass, cast bronze bells will
ring. Not sure a cast nodular iron bell would, completely different material
that is used in machinery frames.
4. In the past the engines were machined to fit everything, not true today with
the flexible planning and machining processes.
5. Yes, the air-conditioning compressor clutch can make a slapping noise.
6. Damage by a heavy footed driver before you got it is iffy with the present
rev limiters. Only damage I've seen myself is from crushed lime stone long term
storage parking lots etching the brake rotors, (the same as the clutch face on
your compressor clutch).
7. Your co-worker was not protecting GM, how did you make that determination?
8. Machinery can make some noise and run for extended periods of time. In this
case you don't like it, is it detrimental to the machine, most likely not.
9. Mufflers are built to pass volumes of hot air and gasses and the easier they
do that the better the engine works. If there is a noise involved with that
function in a truck it is expected. Are they cheap? Yes, all parts come from the
lowest bidder or the only place they can get it.
10. Is the poor fit your problem? Yes, have it corrected.
11. The '76 Corvette had mat showing or bad paint in 11 places with overspray on
the hood from a left front fender repaint at the factory.
12. The '63 had a cracked rear journal that allowed the flywheel to flutter
whipping the main shaft out of the transmission. They just replaced the
transmission 4 times without checking the engine. The frame was way out of
tolerance and it would eat a set of 4 tires in a few thousand miles.
13. Sheet metal hasn't changed that much in 50 years. Do you mean like the '70s
Ford fenders that rusted through before they were delivered?
14. Paint today will outlast the paint of the '70s any day of the century.
15. Only once did I have a car not start when it was below zero and that was in
the winter of 1962 and my wife never set the choke.
16. The block you are referring to had a die cast block with a high silicone
content and they etched the bores to allow the rings to ride on the hard
silicone. It's failures were not all the fault of the design or the drivers but
was to new to succeed in our driving environment. Bad move on GMs part.
I would see a different dealer with my problem.
Dad is really very knowledgeable when it comes to Vettes.
You are probably getting the best advice you could possibly
get on this group.
g'luck with your problem
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