LS1 engine noise

I just bought a 2001 Z28 with 64k on the odometer and have the after purchase worries....
Describing engine sounds is pretty hard but this is what I'm hearing from
this aluminum engine as opposed to my LT1s. I've placed a stethoscope on the valve covers, intake, heads, block and oil pan but can't detect what I hear and feel while driving.
Cold start, the engine has 'almost' a diesel rattle; its not loud or pronounced but to my ears, it's clearly there. When warmed a little the engine sounds okay until 2k rpm where there's a performance sounding intake rap. Hot, the engine sounds pretty normal at all rpm but there's a light pulse during acceleration that can be felt and heard. All hp engines that I've encountered have this once per revolution pronounced pulse in the exhaust note, otherwise they would sound like sewing machines but with this engine I can actually feel it in the shifter and steering wheel. It's slight but another non camaro gear head noticed it as well.
The intake rap I mentioned beginning at 2k rpm is reminiscent of a 92 3.8L ford engine I once owned. The crank bearings were shot. I'm having a hard time believing the bearings are gone on this engine because hot idle oil pressure reads 45 - 50 psi according to the gauge. Besides that, the ford's engine noise worsened at higher engine temperature. This LS1 gets quieter. I've gone to redline a couple times and all seemed well.
I'm worried that the dealership may have been running 87 octane for the three months they had it on their lot because when they went to fill the tank after the sale, I reminded the salesman it needed premium gas. He was surprised....
I know what my LT1s with automatic transmissions sound like but this LS1 with the M6 is a different animal.
Can someone who has owned this engine for a while tell me what I should be hearing from it? Thanks....
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that is called piston slap-famous on the ls1

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Messenger wrote:

The diesel sound on cold start is piston slap. Harmless, just sounds bad. I believe they eventually redesigned the pistons to make it go away.
Not sure about your other sound - are you hearing some kind of harmonic or ??? On my 01 TA there's a "buzz" around 2k once in a while that's actually the power steering pump - weaving back and forth replicates the sound.
Ray
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ray wrote:

Thanks guys. You're the 5th and 6th people to tell me the same thing. One person advised me to check into the timing chain, just in case.
As for the 2k rpm sound while driving with the engine still warming. The best way I can describe it is that it reminds me of working on a carbureted engine with the air cleaner off and quickly going to wot minus the lower pitch growl. It sounds like an intake vacuum hiss with a mechanical clatter beneath it. Perhaps described as a metallic rattle or a very rapid tympanic rat-a-tat. Very hard to accurately describe....
Regards
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Nice car! I have a '98 LS1 M6, and I'm getting the same noise issue, but it will go away eventually once it warms up.
As for reliability, it's pretty good! I've got 239k on the clock, and it still pulls strong. Took it to the track 3 weeks ago on a stock dying clutch and was still able to pull a 13.5@106... We'll see what happens next year with the new clutch.
What you DON'T want is a tick-tick-tick, in where some idiot took it and shifted 1st, 2nd,3rd, and back to 2nd. A good misshift will mechanically overrev the car, and bent pushrods will result.
Get a good shifter in that car. (either a ripper shifter or the hurst; I like the ripper, as it's not as notchier)
Other than that, make sure that your careful speed-shifting into 4th...
:-)
Messenger wrote:

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db wrote:

Helpful info, thanks.
As for the shifter; a friend is pushing me to replace the factory option hurst that is in the car now. He says the throw and slop aren't acceptable. The "ripper" you mention, is it something the people at Summit would know about? I'm planning on a catback exhaust and *perhaps* an SLP cai - for *today*.
I found a modification on http://www.ls1camaro.net/ that *cuts* away portions of the factory air intake shroud and bottom of the air box. Cosmetics won't come into play as these chopped away areas are only visiible after disassembly but I'm still hesitant to cut up the factory pristine parts. So I'm asking around regarding the SLP cai vs this free modification. If I don't go with the SLP, I'll have the money for the replacement shifter. Drag racing is all but over for the season here and the car is about to go into hibernation but would love to get these performance mods out of the way and give them a road test before the cover goes on.
One thing about the shifter; another car friend supplied me with an article from *High_Performance_ Pontiac* 11/05 magazine that details the slave cylinder restriction built into the hydraulics. Apparently the line orifice is necked down to .064 in order to soften drive line shock. The problem is, the slave cylinder runs low on fluid under sequencial power shifts. Hence, the disasterous 2nd - 3rd & 3rd to 4th missed shift. I think before going to the drags, I'll pull the line and drill it out to .125.
Having had two A4s and still driving one of them, I'm learning the M6. I realize it's critical to learn NOT to pull the stick toward me when grabbing 4th. ;)
Thanks immensely for your input.
Regards
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Messenger wrote:

I have that issue and am extremely interested in it... as I've had a couple of blown shifts at the dragstrip and have to replace the stock clutch this winter. Nothing like living on the edge -> I run a 100 shot of nitrous with a 6 speed and nothing but a throttle switch to prevent spraying it to kingdom come. And yes, I'm insane. Doesn't everyone dump the clutch at 5 grand on drag radials with a stock rear end? :) And I can tell you that even with a weak clutch it'll still leave a 100 foot set of stripes without touching the brakes. :)
Keep me in the loop if you do the mod - and I'll let you know if I do it...
Ray (drive it like you stole it)
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ray wrote:

I'll post the results when I get into it.
If the weather holds up here, I'll be working on the slave cylinder line within the next week or so. I have an SLP loudmouth to go on today. Can hardly wait.
Regards.
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Messenger wrote:

it's gonna be loud when it comes with a disclaimer about being street legal, sorta, depending on your local cops. :)
fwiw, at the strip I saw no diff in ET, picked up 1mph, but the testing isn't done because that's when the clutch started to slip and I've since realized that's why my times went (a) all to hell and (b) all over the map and (c) what that horrible smell was after each run.
Ray
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The LM is LOUD, esp. with 4:10 gears...
The drone can be unbearable. Your neighbours will hate you. :-D
news wrote:

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Messenger wrote:

cutting it up and making the LM install easier, you'll need to remove the RR shock and spring. Don't have to remove the whole rear end, just have to lower it enough to get the pipe out and in a lot easier. IIRC you'll need to disconnect the panhard bar and the sway bar too to get enough droop. oh, and you only need to disconnect the shock off the rear end - you don't need to take it right out.
Ray
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On Sat, 22 Oct 2005 04:28:40 GMT, ray

That's amazing. I blew up the rear end on my 2000 with a stock engine and auto transmission and stock tires... -- lab~rat >:-) Do you want polite or do you want sincere?
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lab~rat wrote:

I have the Torsen rear. Maybe I just got a good one. No noises yet. And a 1.739 60' time - the only non stock suspension parts are the drag radials. Nitrous is worth .2 in the first 60 feet. Ray
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Messenger wrote:

From what I hear with our local camaro club, that the fast-doys.net cold air intake is pretty good! You'll gain much more HP vs the SS hood intake.
If you call summit, they will definatly know what the ripper shifter is. You'll be very happy with it. It would be between that shifter and the pro 5.0 shifter that are the popular ones. (I've never tried the pro5.0, so I can't comment on it.)
Free mods are always cool...heck, they're free! As for the exhaust, some people were able to install a "cutout" on the exhaust pipe, right before the muffler, to get that extra flow to run at the track. (might be cheaper than the loudmouth?) The stock exhaust is restricting for sure, so I'd swap it out with something...

Thanks for the heads up on this! I just got a new kevlar clutch installed, and noticed that sometimes I "miss" gears, which is probably due to that restriction...one more trip to the tranny place for this little mod.. :-)
Dan
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Messenger wrote:

the car stopped obviously and engine running) and see if that replicates the sound. That sounds like the same "rattle" I have - I'm convinced it's either the PS pump or the belt tensioner or something. Done it since day one and never gotten worse or gone away - I attrib it to lack of underhood insulation allowing you to hear all the mechanical noises.
Ray
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news wrote:

I've seen this before in one of the forums; perhaps your post. The sounds I'm hearing are when the car has started @ idle, sitting, and when accelerating past 2k rpm but I'll give your suggestion a try to see if I hear anything. Thanks.
Regards
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