Noisy Ls1
Thread Starter
Instructor
Joined: Jan 2018
Posts: 101
Likes: 24
Noisy Ls1
Looking for some your insight on my 03 LS1 engine. Seems when I first start up the car there is a tapping sound from the engine. Only lasts for a few minutes until it warms up to 140 to 160 degrees. Then it’s gone , oil pressure is around 45lbs running, has a low of 25lbs at idle “hot”, no smoke. The car has 70,000 miles on it, Its very clean and appears well taken care of but I bought it from a dealer so I lack history. I’ve heard these motors can be a bit noisy at startup , my first corvette so lack experience with these cars. Any feedback will be helpful.
Thanks, Bob
Thanks, Bob
Racer
Joined: Oct 2007
Posts: 431
Likes: 22
From: Chester Illinois
Looking for some your insight on my 03 LS1 engine. Seems when I first start up the car there is a tapping sound from the engine. Only lasts for a few minutes until it warms up to 140 to 160 degrees. Then it’s gone , oil pressure is around 45lbs running, has a low of 25lbs at idle “hot”, no smoke. The car has 70,000 miles on it, Its very clean and appears well taken care of but I bought it from a dealer so I lack history. I’ve heard these motors can be a bit noisy at startup , my first corvette so lack experience with these cars. Any feedback will be helpful.
Thanks, Bob
Thanks, Bob
Drifting
Joined: Mar 2014
Posts: 1,823
Likes: 757
From: Marysville Washington
You're fine. 20psi hot idle is very normal. GM minimum spec is 10psi for every 1000rpm. People will tell you "oh, I see 30 something plus psi at idle hot." THAT is TOO high in my opinion. A lot of folks like to throw in the high capacity, or high pressure pumps if they ever get that far into the engind, but they aren't necessarily good for the LS1. Plus, always be suspect of factory gauges. NO ONE makes factory gauges that are up to snuff IMHO 
Mine is a clatter trap when cold with long tubes. I just leave it to warm up until I see the first blip on the HUD for the radiator temp (about 113 degrees) and drive off carefully until I hit 150 oil temp, then it's game on. FYI I see around 25psi at idle.
Side note, never use royal purple in these engines. Mobil-1 5/30 as suggested by the factory for the win. During development, and proving, GM never once changed the oil in the C5 test mules in hundreds of thousands of miles. All they did was top them up, and drop old filters. When you pop open an LS1 that has been fed M1 it's whole life at 150K, and it will look damn near like new inside
Mine is a clatter trap when cold with long tubes. I just leave it to warm up until I see the first blip on the HUD for the radiator temp (about 113 degrees) and drive off carefully until I hit 150 oil temp, then it's game on. FYI I see around 25psi at idle.
Side note, never use royal purple in these engines. Mobil-1 5/30 as suggested by the factory for the win. During development, and proving, GM never once changed the oil in the C5 test mules in hundreds of thousands of miles. All they did was top them up, and drop old filters. When you pop open an LS1 that has been fed M1 it's whole life at 150K, and it will look damn near like new inside
Drifting
Joined: Apr 2007
Posts: 1,517
Likes: 159
From: Lafayette Louisiana
Probably piston slap. Most of the LS1 engines do it on cold start. I even notice it on my Cadillac Northstar if I cold start with hood open. So long if it goes away pretty quickly after engine starts to warm up nothing to worry about. 
Racer
Joined: Jan 2016
Posts: 280
Likes: 21
From: Austin TX
You're good. Mine is exactly the same. 2000 with 160K miles and it doesn't burn any oil between oil changes. When fully warmed up, oil pressure is around 45 when driving and just over 25 at idle.
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Melting Slicks
Joined: Nov 2011
Posts: 3,183
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From: Virginia
Do you have headers? I have an 03 also and have made several posts about the same issue. Some will say piston slap but if yours sounds like mine it is a very distinctive tap rather than a knock. Most seem to think its a lifter pumping up... Do you have a video? I have seen a few videos on youtube that sound identcal to mine. Post a video or audio clip and we can compare.
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Heel & Toe
Joined: Apr 2017
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I agree with everyone else. No need to worry about it, its pretty common. My 02 does it with 60k miles on it and my friends 03 with 15k miles does it aswell (a little louder actually). Just let it warm up before really getting on it.
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
my 5.3 started doing it when it was a few mos old, 180k now. Louder but seems ok.
Switching to dino oil made a night and day difference really quieted it down. What the hell its old anyways.
Switching to dino oil made a night and day difference really quieted it down. What the hell its old anyways.