Help! Value chatter noise after oil change
When I went to get the car and started it up, it seemed fine until I revved the engine lightly a few times. When I did so, I heard a fairly loud chattering noise that seemed to be coming from the passenger side cylinder head. The mechanics agreed with me that it sounded like valvetrain chatter/clatter/ticking.
When we checked the oil level, it looked to be a bit higher than the "operating range" on the dipstick (only by a quarter inch or so), so we thought perhaps the chattering sound was being caused by overfilling. So the shop drained the oil again and then refilled it while I watched. However, when I started the car, the valve chatter noise could still be heard when I revved the motor slightly (as I let off the gas). One of the mechanics thought it would go away after the motor warmed up, so I drove the car around a bit, and he was right -- the chattering sound disappeared.
However, every time I start the car, I now have the same chattering sound. It starts after about 30 seconds and lasts for the first 10 to 15 minutes of driving. It seems to go away once the engine warms up. I think I always had a little bit of valve chatter upon startup, but nothing like this. Anyone know what is going on???
Thanks in advance for any help,
Paul
P.S. - My LS1 is stock, has 40,000 miles on it, and I replaced the spark plugs/wires about 6 months ago. Since then, the motor has been running stronger than ever and it still is, but this noise is driving me nuts!
Last edited by Shatty; May 27, 2008 at 02:46 PM.
By the way, it is a beautiful 70 degree day here in DC, so the engine shouldn't be all that cold.
Last edited by Shatty; May 10, 2008 at 05:44 PM.
The brand of oil that they use at this shop was not the same as I usually use (even though it was still 5W30). This brand seems to be alot more clear colored than the oil I usually use (although I am sure it is not synthetic). I can't remember the name of the brand, but it definitely was different.
Would using a different brand of oil be enough of a difference to cause this problem? The fact that the noise goes away after the engine gets fully warmed-up makes me think that this might be the case. I think I may switch back to my normal brand of oil and see what happens. Thoughts?
On cold start, the noise begins after about 30 seconds and goes away after 10 to 15 minutes of driving. If I then stop and let the car sit for 5 minutes, the noise comes back immediately upon start-up, but goes away after about 5 minutes of driving.
I took the car to a mechanic that I trust, and he thinks that there may be a partial blockage that is preventing oil from getting to the top of the engine as quickly as it should. He suggested that I do an engine flush to see if that clears it out.
What do you guys think? And if I should do a flush, what it the best product/method to use? Is there anything else I should try first?
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I ask because most of the threads that I read on piston slap seem to suggest that it is something that is usually present from the beginning.
I am not saying seafoam will fix his noise but even GM acknowledges that these engines can have piston slap due to excess piston to bore tolerances. The very short piston skirt(to save weight) amplifies the problem.They have several TSB's out about it. They even started coating OEM pistons in 03 to help.
When carbon builds up on the piston skirt it can cause contact with the cylinder wall resulting in the tick. In these cases seafoam can SOMETIMES help. I have 99 Z-71 that has had this issue for the 110K i have put on her (177k total). It causes no ill effects despite what this website says. www.pistonslap.com There would have been a class action lawsuit and/or recall if it actually did any damage. Tons of threads on this in the 99 up truck section of www.Chevytalk.com I suggest you search there and it is often refered to as CSK or cold start knock because on most engines it goes away after a minute or so. FWIW my truck occasionally ticks when warm too. don't worry about it
Even search piston slap on here. 

