Everything operates absolutely perfect and I have detected no leaks . . .
"Pat"?
Sounds like you had the answer all along. Are you trouble shooting from the seat or radiator? There are two books (machanics). Let me know if I am wrong. I thought filters were on the left when faceing the radiator. Exhaust to the right. If you hear a wop, wop, wop. That might be a belt. Look for black soot or paint burn around your exhaust manifold. I have not heard of any cracked ones.
You can't use a Fluke. Well you can, but it will cost a little more than what I will descibe. I like to know what it is. I have used a screw driver with handle at ear. Keeping animals around provides me with a stethoscope. There is also a stethoscope for machanics. The sound pick up or "mic" is a metal like prod. If you find by driving other similar rigs that the sound is normal, the right tool is still used for wellness after many hours on the meter. No different from a soundness check when buying a new horse. Having a Doc check the kids. I suffer with a little tone deafness. We can't always see what we want without an aid.
On the TC40 with the hood up, you might be hearing 4 cylinders breathing in. It's that little thing just above the radiator that feeds air to your filter canister.
If you feel spongy-ness in any cylinders, you may have air.
If it makes funny sounds just sitting there and not running, call the vet.
"What is a weed? A plant whose virtues have not yet been discovered."
Ralph Waldo Emerson (1803-1882)
