Monsoon

So I've had this 1999 Camaro SS for a little over two years now. Since I bought it (in 2013 with about 120k on it) it has had a high RPM knock which presents as an intermittent rattling noise in the 4,500 to redline range. It took a while for me to decide that this was in fact a knock (or detonation) because it sounded so much like something that was physically rattling. But I have searched extremely hard and cannot find anything that would cause this noise by shaking or other vibration and have deduced that it must be detonation. I even removed the exhaust and checked for any loose bits by the cats with no success.

It only does it under load. I could rev it right to redline repeatedly with no knock (or ping?) whatsoever. But, when revving under load of actual acceleration it begins to make this noise. I've tried high octane gas (over 95) with no improvement. I've replaced the fuel filter. I've tried about all of the possible fuel (BG44k, Berryman, Lucas etc.) and combustion chamber cleaners with no lasting effect although the Mopar Combustion Chamber Cleaner did seem to work for a couple of days before the knock returned. I theorized that it could be an issue with the spark plugs being too hot so this past weekend I moved one range cooler (from AC Delco 41-110 to 41-104). While I had the plugs out I snaked in my little borescope camera (bought on Amazon for under $20) and shot the following video...


It appears that I have leaky valve seals. I shot this video in the morning when the car was cool after using it the night before. It had been sitting for about 12 hours. I don't note any particular loss of oil...maybe a half a quart over 3,500 miles (about two or three months of summer use) and I've never seen any smoke out the exhaust on start up (or any other time for that matter) but the oil is definitely there on the cylinders.

I'm up for changing out the valve seals but I have not done this job before. Can anyone confirm that this looks like the correct fix? If so, what else may I need to do to clean up the pistons? I have a couple more cans of MCCC that I can use. I really don't want to pull the heads if not absolutely necessary. The car runs great and pulls strong, it's just this blasted knocking that's driving me up the wall!

Any help would be appreciated.

Also, I'm fairly proud of myself for getting that number 8 plug and wire changed myself...pulling the coil pack is definitely the way to go!

HCI2000SS

iTrader: (2)

Very interesting. So does it knock in every gear around 4500?

Monsoon

It does it in first, but quickly as that RPM range goes past so quickly. I can get it to do it longer in second (especially if I find somewhere to be climbing uphill). I really haven't tried winding it out faster in third or fourth.

Guess I should mention that this is an A4 car.

Monsoon

I originally got the idea that it may be leaking valve seals from this thread...

https://ls1tech.com/forums/general-m...69-camaro.html

Darth_V8r

iTrader: (4)

One source of oil in the combustion chamber is the PCV - especially in the 98-02 F cars. Oil mist will also cause detonation. Since you've already gone to a colder plug, maybe the next step is a catch can for the PCV.

It is also possible a previous owner dumped a box hypertech tune in there vs having it tuned right.

Monsoon

Absolutely I get oil from the PCV system. I know that because I did install a catch can late last year. I get a half to three quarters of an inch out of the can each time I change the oil.

Also, it's Tuned by Frost.

Darth_V8r

iTrader: (4)

If frost tuned it, it's not the tune