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post #1 of (permalink) Old 06-20-2002, 08:03 AM
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Valve tapping sound?

I posted this over on the IFS board and I thought I'd throw it out here to see if anyone could help. I have a 98 Vortec 5.7L 350. I recently went on vacation and the truck sat at home for about 6 days. When I started it up to go to work yesterday it had a loud tapping sound like a valve maybe. I stopped after a little driving. Everytime I started it after it sat for a good little while it would do this. This morning it started with no sounds. It is pretty warm out here so I wouldn't think it would be because it was cold. Any ideas?
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post #2 of (permalink) Old 06-20-2002, 09:00 AM
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Re: Valve tapping sound?

mine does that if I run cheap gas. Gotta run at least mid grade other wise mine pings. ALso on my old motor it pinged cause timing was off. Dunno if that relates though
post #3 of (permalink) Old 06-20-2002, 09:16 AM
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Re: Valve tapping sound?

It does have cheap gas in it right now. It sounds more like a tapping of a valve than an engine knocking from gas. Someone mentioned it might me a sticky valve due to carbon buildup and that it happens with Vortecs and wasn't something to worry about, but I don't know. They said use some GM top engine cleaner for it. I doesn't happen all the time and goes away so I don't think it is anything real major but I have been wrong before...
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post #4 of (permalink) Old 06-20-2002, 09:19 AM
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Re: Valve tapping sound?

Hmmm. I've never been around the newer vortec fuel injected computer controlled trucks so I'm just guessing. Sounds like that could be a possibility. Run it hard for a little and see how it goes then.
post #5 of (permalink) Old 06-20-2002, 09:32 AM
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Re: Valve tapping sound?

Rick,

My dads 97 K2500 with the 5.7L did something similar when he was gone for 2 weeks. It was most likely that it was cold from just sitting there. And I had put cheap gas before he had left as well.

So what happened is when I turned it on after say a week of no use, I noticed a pinging and a bad vibration. But after that all was fine. It could just be that it was cold etc.
post #6 of (permalink) Old 06-20-2002, 09:36 AM
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Re: Valve tapping sound?

I was thinking that as well since it didn't do it this morning. I'll see what it does when I leave for lunch. I'll put better gas in it tonight probably and I'll check into the cleaner when I do my tune-up.
post #7 of (permalink) Old 06-20-2002, 10:47 AM
 
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Re: Valve tapping sound?

<font face="Times New Roman">
<font color=green>This happened to my brother-in-law on his 98 Burb. We used flushing oil on it twice and a can of Marvel in the oil, the tapping got better immeadiately and gradually went away completely over about a week.
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