Ever notice when you get your old Farmall running exactly the way you want it how easy it is to detect something is not right. Last year it was my F14 - started up after sitting all winter and sounded odd.After a brief panic and seeing dollar signs turns out it was only the muffler I have on it going bad. Last fall when I put my M away for the winter I noticed a clicking sound coming from the engine near #4 piston.Same panic feeling as the F14. Started it up tonight to disk my garden and heard it real clear. Time to investigate as it is not always as noticeable but always there to a point. I hear the noise only on the exhaust side, near #4 piston toward the top of the motor. Nothing there mechanical. Start moving my hand around the engine and find short blasts of hot air coming from the exhaust manifold.It appears I have a manifold gasket leak and not a pending disaster. Wife says she wishes I was that much in tune with her. I told her I would be when she hits 72 (age of my M). Man, women have no sense of humor. She has put up with it for 38 years in a couple of weeks.Maybe she will get me a manifold gasket for our anniversary LOL.