04 Sierra 4.8 Tapping Upon Startup

[tombstone]

Hello All!

 

Last week I picked up my new to me 04 Sierra with the 4.8l V-8. It only has 12000 on her and is a pretty sweet ride imho.

 

Yesterday, I heard a slight tapping upon startup. I turned the truck off and started it again and the tapping was gone. I ran the truck for hours before and didn't hear the tapping. I did put about $20.00 of 87 octane in it - perhaps that is the problem.

 

I ran it again today and there was tapping on startup. I turned it off and tried it again and all was good. I'm still covered under the factory warranty, but wanted to see if anybody could shed some light on the situation.

 

Thanks!

 

tombstone

[s-ten]

I think what you are hearing is the clicking (only on start up) that is common on most of GM's newer small blocks. Ever since they came out with the generation III truck engines in 1999 there have been complaints about this, although it does not seem to harm anything. Even my 350 does this for about 20-30 seconds after it starts. As far as the 87 octane, that is all that is required for these trucks so that should not be a problem.

 

That is my take on the situation anyway.

[Wilsonmetro]

Ditto for mine. In the morning, the engine slaps for the first 20 yards or so, and I just take it real easy until it gets into its groove. My truck has 90,000 miles on it, and apparently it hasn't caused any problems yet. I think of it as personality.

[z85violator]

Ditto for mine. In the morning, the engine slaps for the first 20 yards or so, and I just take it real easy until it gets into its groove. My truck has 90,000 miles on it, and apparently it hasn't caused any problems yet. I think of it as personality.

 

 

 

 

my 2000 w/ 145,000kms justed started making the same noise, for about 15 secs in morning under acc up hill. doesn't sound like lifter tick more like a loose rocker lever.goes away for the rest of day. not to worried about it

[tombstone]

Hmmm ....

 

What exactly is the tapping? I had a car that did this and it was just the valves that needed adjustment. The same car had the loudest fuel injectors I've ever heard.

 

I'm going to make an appointment for the steering shaft and am planning on mentioning this as well.

 

Weird.

 

tombstone

[C & A s Dad]

Tombstone,

 

With only 12K on the clock, this noise should not be a lifter but you never know. I have sold and recommended Rislone for years for lifter issues. If you do not find out anything at the dealer, the next time you change the oil, leave out one qt and add a qt of Rislone. If it is a lifter issue, you noise will likely go away. Even if it does cure your noise, it will not hurt a thing.

[jhm]

Hmmm ....

 

What exactly is the tapping? I had a car that did this and it was just the valves that needed adjustment. The same car had the loudest fuel injectors I've ever heard.

 

I'm going to make an appointment for the steering shaft and am planning on mentioning this as well.

 

Weird.

 

tombstone

This sounds like cold start knock. The pistons slapping against the cylinder walls due to the short skirts on the pistons. Some do it worse than others. Mine never did it at all until this past winter.

[tombstone]

What is puzzling me is that this also occured after the motor was warmed up.

 

I drove around for a bit, albeit short distances, and stopped at a store for a few minutes. When I got back in and fired her up that's when I heard the ticking.

 

I've been trying to get in touch with the dealer, but keep getting voicemail - that bothers me as well.

 

Oh well.

[jhm]

What is puzzling me is that this also occured after the motor was warmed up.

 

I drove around for a bit, albeit short distances, and stopped at a store for a few minutes. When I got back in and fired her up that's when I heard the ticking.

 

I've been trying to get in touch with the dealer, but keep getting voicemail - that bothers me as well.

 

Oh well.

This added information does not sound like CSK. Something else is going on. You are in warranty, they have to fix it. Nobody answers the phone at the dealership??? Take it to another.

[tombstone]

I found one that you can actually talk to a person. I'm dropping it off on Monday night. I'm going to drive it a bit between now and then and try to document temps and other things on how they relate to the ticking.

 

I'm also getting the intermediate steering shaft issue taken care of.

 

Anything else I should throw on their plate?