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5.3 Vortec with New Tapping noise


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#1 tmbm50

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Posted 09 October 2006 - 03:18 PM

I have a 99 5.3l GMC Sierra with about 90k on it. It just recently starting tapping loudly for at least a few minutes during driving. Even if it's 75 outside it taps for the first few minutes. Synthetic Oil hasn't helped.

I don't think this is the "piston slap" considering it's just starting now and it last longer than the 10-15 seconds most people report.

Where should I start looking? I was told these vortecs don't have a conventional lifter so I can't look there.

Thoughts?

Tim

Edited by tmbm50, 09 October 2006 - 03:18 PM.


#2 GM-Tech

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Posted 09 October 2006 - 03:40 PM

Of course it has conventional roller lifters. What did they say it has? Granted, you have to pull the heads off to get at 'em, unlike the older engines where they were just under the intake, but otherwise, they're just a lifter like any other.

My next step would be to try to nail it down to a piston noise or a lifter noise. Normally, I might be able to tell just by listening to it, but I can't hear anything from way over here. :rolleyes:

Cancelling a cylinder would make the noise go away (maybe not 100%) when you cancel the offending cylinder and it's a piston noise. Cancelling a cylinder would have no effect on a lifter that's noise. It's still going to make noise.

#3 tmbm50

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Posted 09 October 2006 - 03:50 PM

Ok, I'll give that a try if you can tell me how to "cancel a cylinder".

Back in the day when I use to work on my cars (Early 90's) I would have though this sounded like lifters tapping. So when I brough it to the shop and asked them to take a look he said "No it's not that...they don't have lifters" and then he said I probably needed a new engine becuase it's likely the crank shaft and the whole engine would be useless. All this without even hearing it or looking at it.

So I figured I would take my own stab at it.

-Tim

#4 GM-Tech

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Posted 09 October 2006 - 04:38 PM

Ok, I'll give that a try if you can tell me how to "cancel a cylinder".


Since you probably don't have a scanner that can do this, just pull plug wires, one by one. A piston noise will usually noticeably change when you remove the pressures of combustion.

I wouldn't be taking that truck to anyone that says it has no lifters!

#5 C & A s Dad

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Posted 10 October 2006 - 10:57 AM

Tim, if you determine that it is not Piston noise, I would have to assume that it is a lifter issue.

I would start by changing my oil, leave out one qt and add a qt of Rislone. Give it about 500 miles and if this does not quiet it down, you either do not have a lifter problem or it is so severe that you will need to get out your wrenches.

Rislone is not a mechanic in a bottle but it is a wonderful product that has helped a lot of engines with lifter issues. The best thing is it will not do any harm at all by trying it.
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#6 GM-Tech

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Posted 10 October 2006 - 12:23 PM

And if Rislone doesn't work, try Marvel Mystery oil. We've had good success with that on sticky lifters.

#7 tmbm50

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Posted 10 October 2006 - 03:45 PM

Thanks for the suggestions. I'll try the cylinder deactivation thing this weekend and if it appears to be lifters I'll try one of those add in products.

If it is coming from a cylinder I'll be back with more questions :rolleyes:

Edited by tmbm50, 10 October 2006 - 03:45 PM.


#8 BowTieDude

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Posted 10 October 2006 - 08:46 PM

You know, with all the noises that are frequently complained about on the nbs trucks, if GM couldn't make the new '07 trucks quieter, hopefully they at least used more effective sound dampening insulation. :devil:


I hope your problem isn't serious. These trucks seem to run a long, long, time even with their quirks.
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#9 yukon4wd

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Posted 22 October 2006 - 04:50 PM

You know, with all the noises that are frequently complained about on the nbs trucks, if GM couldn't make the new '07 trucks quieter, hopefully they at least used more effective sound dampening insulation.  :gmc:


I hope your problem isn't serious. These trucks seem to run a long, long, time even with their quirks.

<{POST_SNAPBACK}>


Not sure if this is related... but anyway.

My 04 Yukon staprted tapping a while back, I just assumed it to be the well known piston slap, so since everyone says its not harmfull I sort of ignored it. BUT I really have no idea what piston slap sounds like. So maybe it is lifters. (If it was a 30 YO truck with the old Hydroaulic lifters, that's what I would expect, but ...).

Anyway how would I know that its just the usual piston slap, and not a stuck lifter.

Thanks
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