I have Ford/New Holland 2120 tractor with a Shibaura engine. I was using it today to move heavy wet mulch and everyone once and awhile I would hear a squeal (like the sound of air being let out of a tire) from under the hood. I stopped the tractor and noticed a leak on the ground. I opened the hood and it was all wet. I think it is diesel fuel. The engine topside, by the injectors, was wet along with the side of the engine. None of the fuel injectors are loose and I did not see any apparent leak when I started it up and accelerated. I suspect one of those 3-5" return hoses in series might be leaking. Are the return lines pressurized? Would a return line leak make a squeal when the engine is fully engaged (full acceleration). I stopped, cleaned and restarted multiple times trying to find the leak but to no avail. Thoughts?