Trane gas furnace, at least 11 years old, mounted in attic. Earlier tonight it started making a "clunk clunk" sound, followed about three seconds later by a fainter single "click". A couple of seconds later it starts again with the "clunk clunk."

Turn the furnace off and everything stops. Wait a few minutes , turn it back on and the cycle starts again. After an additional 30 to 60 seconds the fan starts But, there is no light-off - no flame.

Can't tell where the "clunks" are coming from. It might be the gas valve. With my hand on the gas valve a vibration can be felt there with each clunk. The 'click' seems to come from deeper inside the furnace.

Any suggestions or ideas? Thanks.

Sounds like the ignitor is bad. Could be spark or hot surface. It should glow or spark depending on type.