C4Coupe

I've only had the 92 C4 for a couple weeks now and "lovin it"! It's a driver not a show car by any means. With 86k miles I thought 5k wasn't a bad price to pay. Any way had something happen today and I sure could use some advice from the experts on where to start. When placing the auto trans shifter in 1st or 2nd stopped on idle I can hear an odd vibration rattle type of noise. Doesn't make the noise in drive, overdrive, neutral, reverse, or in park. Any suggestions where to start looking? Thanks!

Railroadman

Can you tell where the noise is coming from? Under the car? Under the hood? Inside the tranny (vibration through the shifter?) In the dash?

When you keep your foot on the brake but gradually add power, does the noise increase, go away, or stay the same?

Can someone else standing outside the car hear the noise and maybe help locate it?

Narrow it down and give more details and maybe we can help you.

C4Coupe

Thank you! The noise is from under the car. I'll have the Mrs. listen tomorrow. She has better hearing than me! I'll also give it some gas with my foot on the brake. If she says the engine area we'll trade places and I'll pop the hood and try to narrow it down some more. I didn't realize it before but there really is a "Corvette" community!

Railroadman

Nobody knows it all, but collectively we come pretty close!

SWAG but I'm wondering about the heat shield on the cat. Working from memory since it's been a while since I was under there, but I had a stone between the shield and the cat and it sounded almost like a rod knocking (probably because we were about 750 miles from home and strange noises made me paranoid ) In my case it worked itself out after an hour or two of driving and no further problem.

Don't worry, noises and glitches are all a part of the fun. You already know enough to drive it and enjoy it, and you're sure not going to lose much money at that price.

bac22

I don't recall if there are heat-shields on the exhaust (probably around cats) but I've had those things rust out at one of the bolt holes and with the engine idling at just the right RPM's you'll get an annoying rattling sound.

92ragtop

Also check for any contact between the exhaust and the frame.

87Vettel98

There is, in fact, three heat shields on the exhaust system. There should be two where the downpipe passes the oil pan (on both sides). There is also a heat shield around the cat but I highly doubt you'll have any issues there. At least I never have if it's not rusted out it's probably fine because those heat shields are on there pretty good. I would say do the easiest thing first pull the shifter boot and center console plastic and make sure nothing has made its way into the back of the shifter. There is a small opening in the far back of the cup holder that can let loose change in. If it occasionally takes a few tries to get the shifter into 2 or 1 that could be it. Happens more often than you would think.

C4Coupe

Well it turns out the noise was a blessing in disguise! Thank God I was able to find a service manual on Ebay last week! Found a big ole mouse hotel under the passenger seat when I pulled it and the console. There was stuff you wouldn't believe that had fallen into the shifter area too. Plus that smell I thought was just old car smell is now gone!The car had been sitting outside in the country for the last 6 months or so after the lady that owned it had passed away. No live varmints were there, but Holy Jesus the smell! Happy Ending!!! Thanks a lot for helping me!

Railroadman

Glad you evicted the meeses, but what was making the noise?

ghoastrider1

I am with swag on this one. very common area for this noise.

C4Coupe

Oh ****, that was the whole point on this thread lol! Got so wrapped up in this mouse thing. I tightened the front exhaust spring hanger ( loose ) on the trans and the noise is gone! Don't really understand what difference it made what gear selection the shifter was in. Maybe that was all in my head. I hate noises. A good friend of mine is ASE certified in everything and he would rather call in sick than deal with customers with a noise complaint similar to this one ( rate mechanic ).
After hosing the carpet down under the passenger seat with Lysol and Fabreeze I put a fan on it. Almost smells April fresh now. Got very lucky with no damage to cause malfunctions with the electric seat wiring or the lumbar tubes. Whew! Thanks again for the advice!!!

Railroadman