mpmussel

Hello all, any help would be greatly appreciated. I have an 04 C5 Coupe (Z51 w/ 6-speed) with 58K miles on her. For some time now I've noticed that when I do an extended highway trip, eventually I start hearing clicking/ticking noise coming from the engine/firewall area. At first I thought it was engine pinging from maybe a tank of bad gas. However, I believe I have eliminated that possibility since it occurs during light, not heavy, throttle, it's just as loud when coasting off throttle, and I've experienced it with multiple tanks of gas (and I always run premium). I did some testing this weekend and found that 4 times in a row it will consistently start doing it after about 30 miles of travel. Normally I'm running 60-85 mph in 6th gear. Once it starts I tried shifting down to 5th and it still does it. If I stop the car, say to get gas, about 30 miles later it comes back. If I slow down and run it hard up through the gears, the sound goes away for a bit, but eventually comes back (say 10 miles later). It doesn't sound healthy at all, but the car isn't spitting check engine messages or any codes. I found the thread below which sounds very similar, if not the same as my problem, but there was no resolution posted and the hotlink within the below thread doesn't work anymore either. Anyone know what this is??

https://www.corvetteforum.com/forums...-cruising.html

Thank You!

Bill Curlee

Noises are very subjective and what you describe may not be what it actually sounds like if we listened to it.

Can you record the noises and post up a vid??

Have you tried to turn off the HVAC system and see if that eliminates it??

Patches

I noticed this same phenomenon just as you describe it on my 2002 when I first bought it.

Here's the thread I posted in discussing the issue. Some possible explanations in it.

https://www.corvetteforum.com/forums...ixth-gear.html

mpmussel

Patches and Bill, Thanks for the replies.

Bill, I never thought about cycling the HVAC On/Off to see if it affects it. I'm going to take it out again for another test run and check that out.

Patches, that is some interesting information and theories, but did anyone ever give you a definitive answer and fix, or does your car still do this?

This is an unbelievably annoying and ugly sound. I love Corvettes for their performance, style, and speed for the price, and I know at this cost they aren't supposed to have the fit-and-finish of a Porsche, but this kind of stuff is ridiculous.

Any further info would be much appreciated.