tapping noise
 

hey guys I'm having another problem with my 85 blazer that I hope ya'll can help me with. when my truck is idling and when speeding up it makes this really loud taping noise, if you stay at one speed with your foot just a little on the gas it does not do it but if you step down on it it starts up again. as close as I can find its coming from around the torque convertor and flexplate. anyway its really loud and is very annoying.
thanks for any help.

350 small block, turbo 400 trans HD.

Could be a cracked flex plate or possibly an exhaust leak.

Not sure what a flex plate is :p, but it definitely sounds like it could be an exhaust leak for sure. It has been my experience that leaks are pesky problems.

Get a section of rubber hose to use as a stethescope. Have a helper start the truck, parking brake on and foot brake applied. Then put it in gear and slowly accelerate to try and hear the tapping. Put one end of the hose near your ear and move the other end of the hose to the area where the sound is coming from. This should help to pin point the spot where the noise is coming from.

I had a similar noise coming from my transmission before. I couldn't figure it out for the life of me, until I noticed that a bolt was slowly unscrewing itself from the torque converter/flywheel. After tightening the bolt (and throwing some thread locker on it) the noise went away.