While torquing my fasteners they have been breaking. Would the culprit be the 30 year old fasteners, or my cheap torque wrench?

 

Could be either.
Are you confusing inch/pounds with foot/pounds or Newton/meters with anything else?

 

Well, it's happened a couple times. The wrench would click out like it should, then the next bolt would snap. After the first time I tried to be more gentle, in case maybe I was turning too hard and just not feeling the click, but yet it still snapped. I was doing engine covers, so only 15-20 ft-lbs was the requirement. I had it set for 18 I believe, until I broke one, the next time I used it I tried at 15. It's not every bolt is snapping, but one is enough to be annoying, I guess.

 

Sometimes, there are a couple that are different lengths (to accommodate a clutch line guide for example), if you tighten those past bottoming out, they'll snap. And yes, it's very annoying...

 

Look at your bolts before you put them back in, if they're skinnier in the middle than the rest of the bolt, they're getting ready to break. I learned this by replacing brake pads over and over again on my track bike. I was torqueing the caliper bolts and noticed the torque wrench was getting easier to lever instead of harder. So I stopped, removed bolt and noticed the bolt was hour glass shaped. Replaced with new.