Ok" guys here's the story: I think I've done every test you ask I've bought a temp gun,a thermometer,and a new meter. I checked the sensor, checked the gauge and the wiring, checked with the cap and with out the cap, did static tests including checking the flow and temp by sticking my finger in it and came to the conclusion that the t-stat was at fault and stuck open, the gauge still remained on cold, I opened the system and checked the t-stat but it was closed??carefully removed it and it looked fine the dingle(air bleed) it was as it should be well I stuck in a new t-stat since I purchased one of them and put the system back together add'ed fluid and started the Eng, low and behold the gauge worked I worked the tractor the next day turning it off and on several times and it always worked fine TO DAY I PUT THE OLD T-STAT IN A POT OF WATER WITH A THERMOMETER AND GUESS WHAT IT OPENED AND CLOSED. APROX.OPEN AT 71C AND FULLY OPEN AT 85C . PLEASE,PLEASE EXPLAIN THIS TO ME. I just do not understand. (bad wire?)