Hey guys. Ive had a tapping noise coming from my stock 289 for a while now. I can hear it louder now after I put a new exhaust system on, and its very noticeable. I was wondering if anybody could diagnose the problem as Im guessing its not normal for this to be happening. You can hear it clearly in this video. The car was in drive and I was hitting the gas lightly. Its much quieter when the car is idling in park.

http://www.youtube.com/watch?v=zj2lc...eature=channel

 

can you hear from wich side ? and if the sound comes from the heads (valvetrains) or lower in the engine.

Its hard to tell from a video. Take a long screwdriver, put the metal part on the engine on different places and put your ear on the handle. That way you can check the location of the noise.

Could be cam shaft bearings, big end bearings or crankshaft, tilting piston (like my old engine). It doesnt sound healthy to be honest !

 

i would make sure all valves are tight, also are your exhaust manifolds lead all 4 into 1 or are they two Y's?

 

They are long tube headers. All four into one.

And good advice with the screwdriver. Ill try that soon.

 

Maybe something is hitting something? Did you check all he parts near the fan? lol
I am not expert but if its not that could be the pistons clanking. Happened to me before I rebuilt the engine.

 

Look (listen, feel, etc.) all the way around for an exhaust leak. If there are none, check the valves for bent pushrod or mushroomed valve tip. If all that's OK, you should adjust the valves.

 

Sounds like an exhaust leak. Not just from the type of sound, but firstly it's WAY too fast to be valvetrain related(valvetrain noises are at half engine speed). And it doesn't sound bottom end mechanical. Does the sound change once the car warms up?

 

The frequency of the sound depends on how fast Im going/RPM. The more I hit the gas, the more frequent the tapping. If I slowly get onto the gas, it taps slowly. Its hard to tell in the video because Im holding it at pretty much the same RPM the whole time.


PS: This sound was here before the new exhaust, but its more noticeable now because it is amplified by the louder exhaust system.

Im going to annotate the youtube video for when I decrease the RPM and when I put it in park, so you can tell the difference in sound.

 

Just a small test to rule out an unlikely source:

Try stepping on the brake with the motor on (parked) and putting it in reverse. Does the tapping stop? If so, it could be your flex plate.

It is more likely to be a leak from the headers or a valve tapping. Try a tube from gift wrapping paper to listen if you don't want to dive under the car to hear if it's exhaust. Good luck.

CP

 

I'm with 67mustang302. I think it's an exhaust leak. I have several, so I should know the sound