Classic Mustangs (Tech)Technical discussions about the Mustangs of yester-year.
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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.
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?
Who cares how much horsepower it has, all that matters is how fast it goes!
Untested 331, lots of suspension, chewing up corners.
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.
check this easy thing out, just to rule it out, jack up car a little, get a 9/16 wrench and take off the 2 screws that cover the flexplate on the bottom of the tranny. its very easy, then start her up and see if the noise went away. perhaps the plate is on backwards or its bent. perhaps your screws on the flexplate are rubbing somewhere.
You can also check for exhaust leaks with the car running. Just use your hand and feel for exhaust coming out somewhere it shouldn't. This works better the farther you go back on the exhuast. It doesn't work that well right at the motor since the fan is moving air. Also you can look for black exhaust residue somewhere that would indicate that there is a leak.
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