Tapping noise
Thread Starter
Racer
Joined: Jan 2005
Posts: 433
Likes: 0
From: Pittsburgh PA
Tapping noise
Hello,
I have a 1991 coupe that is making a tapping sound from underneath of the car. It almost sounds like a valve tap, but is for sure from underneath the car. (Upon opening the hood the sound is not as strong as it is when you look under the car.)
The tapping sound is never there when the car is cold. When the car heats up to normal operating temp, the tapping will sporadically start. The sound does not seem to be there all of the time, but once it starts it doesn't quit until the car has cooled down overnight. (It doesn't seem to have any rhyme or reason to it, I drove it one day for 10 miles and the sound was not there. Drove it to the corner store and the knocking was there upon returning home.)
There doesn't seem to be any horsepower and\or performance loss when it is tapping. My first suspicion is the cat converter, but I am far from a Corvette expert.
Anyone have ideas what to look at before I take it to the repair shop?
Thanks !!
I have a 1991 coupe that is making a tapping sound from underneath of the car. It almost sounds like a valve tap, but is for sure from underneath the car. (Upon opening the hood the sound is not as strong as it is when you look under the car.)
The tapping sound is never there when the car is cold. When the car heats up to normal operating temp, the tapping will sporadically start. The sound does not seem to be there all of the time, but once it starts it doesn't quit until the car has cooled down overnight. (It doesn't seem to have any rhyme or reason to it, I drove it one day for 10 miles and the sound was not there. Drove it to the corner store and the knocking was there upon returning home.)
There doesn't seem to be any horsepower and\or performance loss when it is tapping. My first suspicion is the cat converter, but I am far from a Corvette expert.
Anyone have ideas what to look at before I take it to the repair shop?
Thanks !!
Thread Starter
Racer
Joined: Jan 2005
Posts: 433
Likes: 0
From: Pittsburgh PA
Originally Posted by Jerris
Check for loose pieces inside your cats. Try shaking or hitting them with the car off while hot to see if you can duplicate the sound.
Jerris
Jerris
I will give that a try when I get home today. If that is in fact the problem, is it hard to "gut" them?
Thanks again for the help.
Burning Brakes
Joined: Nov 2003
Posts: 1,234
Likes: 5
From: Herriman UT
I had some lifter noise (tapping) only after warm up on the 86. I even installed a 2nd set of new lifters. Finally, experimented with various weights of Mobile 1 oil. 5W-30, 10W-30 = tapping when warm. 5W-40, 20W-50 = no tapping when warm. I settled on the 5W-40. (The 20W-50 was Valvoline VR-1)
Last edited by geezel; Feb 28, 2006 at 12:13 PM.
