Tapping Noise?
Thread Starter
Racer
Joined: Jan 2005
Posts: 433
Likes: 0
From: Pittsburgh PA
Tapping Noise?
Hello,
My 91 C-4 is making a "tapping" noise that sounds like a valve knock, but seems to be coming from underneath the car. The noise does not increase or decrease with RPM's, if you shut the car off, it will quit for 30 seconds or so and then come right back. I am not a "skilled" mechanic, but from the searches I did, the catalytic converter seems to be the leading suspect. I was hoping someone here would know how to tell me what to do to try and pinpoint the sound.
Thanks !!
My 91 C-4 is making a "tapping" noise that sounds like a valve knock, but seems to be coming from underneath the car. The noise does not increase or decrease with RPM's, if you shut the car off, it will quit for 30 seconds or so and then come right back. I am not a "skilled" mechanic, but from the searches I did, the catalytic converter seems to be the leading suspect. I was hoping someone here would know how to tell me what to do to try and pinpoint the sound.
Thanks !!
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Look for any place where the exhaust system or other metal is very close to the frame, shifter lever, etc.
Since it isn't RPM dependant I don't think it's from engine internals or accessories.
Since it isn't RPM dependant I don't think it's from engine internals or accessories.
Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
I agree with 65Z01 that you're exhaust is probably causing it...
Exhaust leaks cause the tapping noise you describe, methinks. But you also may be right with thinknig your Cat is the problem...
I think your 91 uses the same basic setup as my '85.
In my '85, i had a noise like you describe that eventually turned into a pretty ugly knocking noise. It was never there when you started the car, but after it warmed up- the knock would appear.
To determine what the culprit was, I got under the car (we have a pit), and let it run till it was warm enough to make the noise. Then I just listened. I worked my way down the exhaust till I pinpointed the noise coming from the catalytic converter. Once I had that off, the pieces of honeycomb inside just fell out.
Can you safely get under the car while it's running?
Exhaust leaks cause the tapping noise you describe, methinks. But you also may be right with thinknig your Cat is the problem...
I think your 91 uses the same basic setup as my '85.
In my '85, i had a noise like you describe that eventually turned into a pretty ugly knocking noise. It was never there when you started the car, but after it warmed up- the knock would appear.
To determine what the culprit was, I got under the car (we have a pit), and let it run till it was warm enough to make the noise. Then I just listened. I worked my way down the exhaust till I pinpointed the noise coming from the catalytic converter. Once I had that off, the pieces of honeycomb inside just fell out.
Can you safely get under the car while it's running?
Thread Starter
Racer
Joined: Jan 2005
Posts: 433
Likes: 0
From: Pittsburgh PA
Hi Guys,
Thanks for the quick replies. Mikey, I can put it up on the rhino ramps I have for it and get under pretty far. (Changed the oil this way a week ago.) I am planning on doing this once I get home this afternoon.
Thanks!!
Gene
Thanks for the quick replies. Mikey, I can put it up on the rhino ramps I have for it and get under pretty far. (Changed the oil this way a week ago.) I am planning on doing this once I get home this afternoon.
Thanks!!
Gene
