Mysterious Noise Tapping
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Acct suspended by request 8 Nov 2012
Joined: Apr 2008
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Mysterious Noise Tapping
71 Vette 350/270, base 4-speed, no mods, matching numbers -- There is a mysterious tapping noise coming from underneath the car. It taps in time with engine RPM but it isn't always audible. The engine and lifters are very quiet. It is definitely not coming from the engine or bearings. I lay down beside the car and it (noise) seems to be coming from the 4-speed tranny area. The car has been kind of hard to shift lately. I had the car serviced yesterday and was told the transmission was contaminated badly with water; the oil looked like milk. The tail shaft seal has been seeping for three years, the car has been garaged for the last seven years and never been driven in the rain (possible condensation). I drive the car once every couple of months (or less) for about three miles each time. The car is still being worked on so I don't know if the noise is gone or the shifter is smoother yet. The tranny was drained and flushed, then refilled. Could badly contaminated oil cause the tapping noise and difficult shifting? Could the bell housing dust cover cause a noise like this?
Thanks,
Rick in Tennessee
Thanks,
Rick in Tennessee
Instructor
Joined: Feb 2008
Posts: 128
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Could be coming from the Exhaust manifolds also. You should be able to see smoke coming from around the seals when you rev the throttle. It probably won't be very obvious though. You can take them off and get them machined at napa for cheap. Go ahead and replace the gaskets if this is the case. It this is not the problem, you can get a "sound tester" (not sure what the technical term for it is) and get underneath the car. When you tough any part on the car you can tell where the sound is coming from. It is like a doctor's stethashope
Burning Brakes
Joined: Jun 2005
Posts: 764
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From: THE OLDER I GET THE BETTER I WAS! NORTHERN ONTARIO
I am not sure about a 72 but I do know that on my 79 My heat riser valve on the passenger side was making the same noise as your are describing. The "pull off rod" clip fell off & the ticking kept in time with the engine rpm...just a thought
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Burning Brakes
Joined: Jun 2005
Posts: 764
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From: THE OLDER I GET THE BETTER I WAS! NORTHERN ONTARIO
