Read If Your Engine Ticks/Taps/Pings/Knocks
 

Does your LS1 engine make a weird tapping/ticking/slapping/knocking/pinging noise when its running? Are you concerned? If so, PLEASE read this thread in its entirety.

There is a LOT of misinformation out there about the LS1 when it comes to noises that it makes. In many instances, the sound(s) you are hearing are perfectly normal. Use this guide to help determine if what you are hearing is normal or something to be concerned about.

Situations

Read through all the following situations and see if any of them sound like your situation to help diagnose what you may or may not be hearing.

1. There is a light to medium loudness tapping noise that you hear at idle and under light acceleration when the engine is cold. The sound may be even louder when the weather is cold, but the noise goes away or quiets down significantly when the engine warms up.

This is perfectly normal. ALL LS1s make this noise when theyre cold. The reason for it is there are different types of metal used in our engine and when the metal is warming up, different metals have different expansion rates, so therefore, small gaps get created as different metals are warming up at different speeds, causing a little more noise than normal. There is nothing to worry about.

2. There is a quiet ticking noise that I hear when my engine is idling. It doesnt appear to get any louder at acceleration and is loudest when the hood is up and I put my ear close to the top of the engine.

Once again, this is perfectly normal. Modern electronics and increased tolerances in high output engines such as the LS1 put additional strains on an engine that may not have existed on a less advanced motor. This noise you are hearing could be from one of 3 sources, all of which are totally normal. They are, lifters, valve train, or fuel injectors. Our fuel injectors are especially noisy and are probably what youre hearing, but as long as its coming from the top of your engine, is consistently the same volume, and doesnt appear to get louder under load, you have nothing to worry about.

3. I have a manual transmission and I think I may have missed a shift recently, or I just bought a used LS1, and I have a loud tapping noise that gets louder and faster as I accelerate. I compared my engine to another LS1 I heard, and mine is noticeably louder.

You may have a bent pushrod. The pushrod is one of the weakest parts of the engine's valvetrain, so if an engine is abused or overrevved, or you accidenitly downshifted instead of upshifted, you may have bent a pushrod or pushrods. In most cases, all you need to do is replace them. Its really not that hard and can be done in an hour with basic handtools. Go to www.ls1howto.com and read one of their heads/cam swap articles and just get to the section that involves taking of the valve covers and rocker arms. Although it is possible for an automatic transmission car to have a bent pushrod, it is very unlikely and usually comes along with some other problem.

4. I recently installed mid or long tube headers, and there is a louder than normal tapping noise that gets louder as I accelerate.

When installing mid or long tube headers, if you still have the stock AIR system, you need to install AIR restrictor plates. All they are is a thin piece of metal with a 3/16" hole through the middle that is sandwiched between the AIR flange and the AIR tube. You'll need one restrictor plate and two AIR gaskets per header. You can buy the plates from most site sponsors or you can make them yourself. If you do not install these, you can damage the AIR check valves which will lead to an SES light.

5. My stock engine runs normally, but whenever I use really cheap or low octane gas, I hear a knocking sound coming from my engine under hard acceleration.

The LS1 is optimized for 91 octane fuel or higher. You will not damage anything by running a lower octane gas, but your engine WILL knock. Thats what low octane gas does in high compression engines. Just use a better gas, or throw some octane booster in there to help you get through your tank. This may also happen with a modified engine with higher compression even if you use premium fuel. In some instances, and engine can be built with too high of compression that always knocks on pump gas. In this case, your timing is too aggressive. Either retard the timing on your cam, or take your car to someone with LS1Edit that can tune your car.

6. I have a 2000+ car and my engine is still very noisy and it doesnt meet any of the above criteria, or I still think something is wrong. I am also using a noticable amount of oil between oil changes, even though nothing is leaking.

Unfortunately, the later LS1s are more suseptible to have whats called piston slap. Some piston slap is considered normal, and there is nothing you can do about it. In some extreme cases, one or more of your cylinder bores can be out of round, or your pistons may need to be replaced. Read the following article posted in Hot Rod Magazine about this topic, and see the service bulletin located in post two of this thread. This may require dealer intervention, but in most cases, GM will tell you you are within tolerances.

GM Also issued a TSB about replacing the o-ring on the oil pickup tube because in some instances it might be not be seated properly, and/or pinched, which would allow a low oil pressure condition, which could lead to increased engine noise, but in most instances this does not solve the problem.

7. I have a modified engine or am spraying nitrous, and after driving aggressively one day, my engine all of a sudden started getting louder at all times, and I feel as though I've lost power.

Unfortunately, there are too many variables in this instance that could describe your problem, and all of them involve diagnosing your motor. You probably damaged something internally, but it could be something as minor as a fouled spark plug. Take your car to a mechanic, or someone who can diagnose engine problems.

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This might be old news, but I saw this in an article from Hot Rod Magazine September 2002. The article says the person who sent this in was from this site, so its very possible this information has been posted here before, but I cannot remember ever hearing about this article, so I thought it might be interesting to all of you.

As I said, credit goes to Hot Rod Magazine, September 2002, pp. 80-81.

I received a memo from GM explaining this after I took my 2001 Silverado for this problem. I purchased it before the SS. It has the 5.3L and it has piston slap, just like the SS. It has not affected performance at all, it now has 60000 miles. The memo read:

(GM MEMO START)

" COLD START ENGINE KNOCK
GEN III Engines 1998-present

It is characteristic to hear a knocking noise after starting a cold engine. This noise will be present until the engine reaches full operating temperature. The lenght of this time and the degree of loudness will depend on: ambient temperature, engine temperature, interior selected and underhood sound deadening level of content.

Engineering has made changes to these engines that reduce rotating mass and internal friction. Specifically, this was done by a significant reduction in the lenght of the piston skirts, piston weight and wall thickness. These changes were done to improve fuel economy, meet customer performance expectations and adhere to government's environmental (EPA) and Cafe regulations.

Due to the thermal dynamics and the expansion rates of different metals and alloys, the pistons are shaped in a way that allows it to expand into a full circle. When cold the piston is not round. It is slightly oblong, its general shape is that of a figure eight "8". the lightweight materials used in the pistons expand at a different rate than the materials that make up the block and cylinder walls.

The factors result in internal clearances when the engine is cold that allow the piston to have a rocking motion in the cylinder, which is the cause of the sound(knock). When the engine reaches full operating temperature, these parts expand to their designed clearances and the knocking sound goes away. This typically will take 2-15 minutes depending on conditions. The clearances are designed to allow engines to operate in extreme temperatures from arctic to desert conditions and perform as required by their owners.

This noise is NOT a defect and does NOT affect the long term durability, function, or performance of the engine. "

(GM MEMO END)

my dad got a 100k mile drivetrain warranty for this on his 2001 silverado. all we did was take in to the dealership to let the service manager hear it and he got the 100k mile drivetrain warranty.

When i start my engine, there is a slight squeeking noise and it appears or sounds like it could be comming from the belt. I dont pay too much attention to it because the noise kinda stopped when I had all my fluids flushed