Tapping Noise From L33 5.3

Buddy67Lincoln · October 6, 2009

I have an '06 Sierra with the L33 5.3. I used to hear a knocking/tapping noise come from the truck when it started in the cold...recently its been hot out and its making the noise in the warm. It sounds like 'valves pinging' but how could the truck be pre-igniting? Its a knock noise at idle, cannot hear it at speed. I mashed it the other week to get onto the freeway and it pinged real loud at high rpm. Almost a rattling noise. I do not do this all the time but in the past it never made any noise like that. The truck has 39,000 miles on it. Could it be bad fuel? I switched fuel companies since I moved and Citco is not on the way to work anymore. Thanks a lot.

rogersinsel · October 6, 2009

I have an '06 Sierra with the L33 5.3. I used to hear a knocking/tapping noise come from the truck when it started in the cold...recently its been hot out and its making the noise in the warm. It sounds like 'valves pinging' but how could the truck be pre-igniting? Its a knock noise at idle, cannot hear it at speed. I mashed it the other week to get onto the freeway and it pinged real loud at high rpm. Almost a rattling noise. I do not do this all the time but in the past it never made any noise like that. The truck has 39,000 miles on it. Could it be bad fuel? I switched fuel companies since I moved and Citco is not on the way to work anymore. Thanks a lot.

Spark knock at idle? Weird. Valves tap, not knock. Try using premium in two tanks and check it out. Check you coolant and oil now.

Buddy67Lincoln · October 6, 2009

I have an '06 Sierra with the L33 5.3. I used to hear a knocking/tapping noise come from the truck when it started in the cold...recently its been hot out and its making the noise in the warm. It sounds like 'valves pinging' but how could the truck be pre-igniting? Its a knock noise at idle, cannot hear it at speed. I mashed it the other week to get onto the freeway and it pinged real loud at high rpm. Almost a rattling noise. I do not do this all the time but in the past it never made any noise like that. The truck has 39,000 miles on it. Could it be bad fuel? I switched fuel companies since I moved and Citco is not on the way to work anymore. Thanks a lot.

Spark knock at idle? Weird. Valves tap, not knock. Try using premium in two tanks and check it out. Check you coolant and oil now.

oil is full, just checked it and changed it last week...come to think of it it was low on oil before I changed the oil a week ago. I had to add a court but the noise was still there after I filled it up. Coolant looks good too. I was going to flush the system before winter too. Yeah at idle there is a light tap noise. I will try Citgo again and see, if not then I will use higher test gas...though I should not have to.

clemsonblozz · October 7, 2009

I have an '06 Sierra with the L33 5.3. I used to hear a knocking/tapping noise come from the truck when it started in the cold...recently its been hot out and its making the noise in the warm. It sounds like 'valves pinging' but how could the truck be pre-igniting? Its a knock noise at idle, cannot hear it at speed. I mashed it the other week to get onto the freeway and it pinged real loud at high rpm. Almost a rattling noise. I do not do this all the time but in the past it never made any noise like that. The truck has 39,000 miles on it. Could it be bad fuel? I switched fuel companies since I moved and Citco is not on the way to work anymore. Thanks a lot.

Spark knock at idle? Weird. Valves tap, not knock. Try using premium in two tanks and check it out. Check you coolant and oil now.

remember that this time of year, you are starting to get the leftover winter blend gas that has been sitting around for half a year or so...

oil is full, just checked it and changed it last week...come to think of it it was low on oil before I changed the oil a week ago. I had to add a court but the noise was still there after I filled it up. Coolant looks good too. I was going to flush the system before winter too. Yeah at idle there is a light tap noise. I will try Citgo again and see, if not then I will use higher test gas...though I should not have to.

98 Z71 SLT · October 7, 2009

L33 is an all-aluminum 5.3 engine

I remember seeing a TSB out on this condition; the oil pickup tube **possibly** may have a tear in it's o-ring seal, causing unusual noises to occur

Check with your local dealer and get it checked out...

Buddy67Lincoln · October 7, 2009

L33 is an all-aluminum 5.3 engine

I remember seeing a TSB out on this condition; the oil pickup tube **possibly** may have a tear in it's o-ring seal, causing unusual noises to occur

Check with your local dealer and get it checked out...

Thanks. Yeah its the aluminum engine so I thought maybe they were a little louder when cold when comparing it to the cast iron block. Thanks, I will look into it.

Buddy67Lincoln · March 9, 2010

L33 is an all-aluminum 5.3 engine

I remember seeing a TSB out on this condition; the oil pickup tube **possibly** may have a tear in it's o-ring seal, causing unusual noises to occur

Check with your local dealer and get it checked out...

Thanks. Yeah its the aluminum engine so I thought maybe they were a little louder when cold when comparing it to the cast iron block. Thanks, I will look into it.

Well I have not heard the noise since I originally posted this. Its back. It not in the mornings when its below freezing, but since its been warming up in the day from 35-50 degrees its been 'tapping' all the way home from work. I listed close this morning and nothing. I will try medium grade fuel mixed with the regular 87 octane when I hit half tank. I wondered if the cold weather has any affect on fuel? When it does act up its particularly bad when under load of course, but really bad when you floor it. I can hear it even cruising as I give it shifts down to go up a small hill keeping speed. That's still low RPM (under 2,000 usually) and you can hear it. Any advice??? I will try the half and half octane mix. Thanks for any help again.

csheatz · March 9, 2010

I have nothing to add about the ticking, mine does not do that. However I do burn about a qt of oil over about 3500-4000 miles. GM will offer nothing more than a statement saying 1 qt ever 2000 miles is just fine!

Buddy67Lincoln · March 9, 2010

I have nothing to add about the ticking, mine does not do that. However I do burn about a qt of oil over about 3500-4000 miles. GM will offer nothing more than a statement saying 1 qt ever 2000 miles is just fine!

Thanks. I was low under 3,000 miles since I change the oil ever 3,000. I am sure if I left it in longer it would be more noticeable that it lost some oil. I have had good oil levels since. Might have just been something else at the time but its fine now. Thanks for the input!

frdfandc · March 9, 2010

Your "knocking" noise under heavy load - acceleration - is pre-ignition detonation. Change your fuel filter and find another station to fuel up at.

Silverado_Monkey · March 10, 2010

Are you sure it's not the "Infamous pistion slap" My 06 5.3 has been doing it now for a few months it only has 35K miles on it, and its using some oil every 3k miles or so...

Buddy67Lincoln · March 10, 2010

Are you sure it's not the "Infamous pistion slap" My 06 5.3 has been doing it now for a few months it only has 35K miles on it, and its using some oil every 3k miles or so...

Yeah mine has about the same miles when it started last year but it only has 46,000 now. I'd be a little disappointed if it needed a fuel filter a year ago! I have not had the oil problem lately but I should check. Pressure is always great too. I have not heard the noise in 2 days now. its been warm out too. I fill up at different stations usually and I know I used a different CITGO last time. Thanks

dlewis1111 · March 10, 2010

Are you sure it's not the "Infamous pistion slap" My 06 5.3 has been doing it now for a few months it only has 35K miles on it, and its using some oil every 3k miles or so...

Yeah mine has about the same miles when it started last year but it only has 46,000 now. I'd be a little disappointed if it needed a fuel filter a year ago! I have not had the oil problem lately but I should check. Pressure is always great too. I have not heard the noise in 2 days now. its been warm out too. I fill up at different stations usually and I know I used a different CITGO last time. Thanks

You know that CITGO is from the dictator in Venezuela, Hugo Chavez......When you fill up at one you are putting ammunition in the rifles of our enemies. Literally.

Buddy67Lincoln · March 10, 2010

Are you sure it's not the "Infamous pistion slap" My 06 5.3 has been doing it now for a few months it only has 35K miles on it, and its using some oil every 3k miles or so...

Yeah mine has about the same miles when it started last year but it only has 46,000 now. I'd be a little disappointed if it needed a fuel filter a year ago! I have not had the oil problem lately but I should check. Pressure is always great too. I have not heard the noise in 2 days now. its been warm out too. I fill up at different stations usually and I know I used a different CITGO last time. Thanks

You know that CITGO is from the dictator in Venezuela, Hugo Chavez......When you fill up at one you are putting ammunition in the rifles of our enemies. Literally.

I never used it before I moved up North. And I know Kwik Fill is American gas. We do have a Kwik Fill but its out of my way...I'm not getting into a battle about politics over gas when our nation is the one's allowing them in. They already have the money once its here and someone is always going to use it.

jro909 · March 10, 2010

my lm7 has some chatter at cold start up at idle, otherwise only noise i get is the woosh of the blade and belt...is it just me or have there been alot of problems noted about the aluminium block lately?