Have done what most everyone else has done. Replaced the idiot light cluster with a factory gauge (white needles) cluster in my '82 GP with a 4.1LV6... Don't know what year of Grand Prix the gauge cluster came out of, as I got it on eBay.
The sending units were replaced for the "new" oil pressure and temp gauges. The oil pressure gauge reads right on the money, as I had the oil pressure checked when I first got the car, which tested out at 47 lbs. The gauge reads about there! 😀 The fuel gauge and volt gauge work fine as well. The temp gauge is another story... :x
Here's some background info on what's been done on the cooling system. When I first got the car, the radiator had a big piece of mineral in the radiator tank and had to be replaced. When the mechanic pulled the radiator out, it fell apart! The heater valve, fan clutch, thermostat, hoses, belts, and antifreeze were replaced as well and the system flushed. Don't think the old antifreeze looked that bad before the radiator was replaced. What little I got to drive the car at the time (before other things happened and couldn't get them fixed then and had to park it for a few years...), never did see the temp idiot light come on, only when starting for the bulb test.
The temp gauge would go up to 240 then 260 and then back down and up again. My mechanic replaced the thermostat and that didn't solve the problem. He thought it may be the temp gauge itself, so I FINALLY found a NOS gauge (#25034056-superceded number w/ orange needle for about an '84 GP according to the parts man). My mechanic bench tested the new gauge and it passed. So I put it on and it STILL read too high!!! :x He replaced the sending unit and it's still doing it! He's checked the engine operating temp with an infrared temp. tool and it's ok. He thinks maybe the ohms resistance of the new sending unit (Part # TS6641- I think it's from NAPA) isn't the correct one for the gauge cluster. He had me look in the factory service manual and it doesn't list what the resistance is for the temp gauge! It only lists the ohms resistance for the oil pressure and fuel gauge, which is 90 ohms. My mechanic thinks that since those two gauges list the same ohms resistance specs, that the temp gauge probably has 90 ohms as well. He also said that NAPA or others probably have listings of sending units with different ohms specs and we just need to find one that will match the new gauge.
Have read about others temp gauge problems here, but they were on Monte Carlos and Cutlasses. Don't know if my mechanic has checked the wiring or not. When I pulled the cluster out again after the first time it didn't work, I carefully cleaned the printed circuit area on it and where it meets the dash with a pencil eraser (read that someone said to clean it with that). Was hoping it was just a bad connection.
Hope someone can steer me in the right direction of getting this "pain in the neck" problem solved once and for all! The dash panel has been off the car for years and I want to get it all put back together and start driving and enjoying the car!!!
Thanks very much!
The sending units were replaced for the "new" oil pressure and temp gauges. The oil pressure gauge reads right on the money, as I had the oil pressure checked when I first got the car, which tested out at 47 lbs. The gauge reads about there! 😀 The fuel gauge and volt gauge work fine as well. The temp gauge is another story... :x
Here's some background info on what's been done on the cooling system. When I first got the car, the radiator had a big piece of mineral in the radiator tank and had to be replaced. When the mechanic pulled the radiator out, it fell apart! The heater valve, fan clutch, thermostat, hoses, belts, and antifreeze were replaced as well and the system flushed. Don't think the old antifreeze looked that bad before the radiator was replaced. What little I got to drive the car at the time (before other things happened and couldn't get them fixed then and had to park it for a few years...), never did see the temp idiot light come on, only when starting for the bulb test.
The temp gauge would go up to 240 then 260 and then back down and up again. My mechanic replaced the thermostat and that didn't solve the problem. He thought it may be the temp gauge itself, so I FINALLY found a NOS gauge (#25034056-superceded number w/ orange needle for about an '84 GP according to the parts man). My mechanic bench tested the new gauge and it passed. So I put it on and it STILL read too high!!! :x He replaced the sending unit and it's still doing it! He's checked the engine operating temp with an infrared temp. tool and it's ok. He thinks maybe the ohms resistance of the new sending unit (Part # TS6641- I think it's from NAPA) isn't the correct one for the gauge cluster. He had me look in the factory service manual and it doesn't list what the resistance is for the temp gauge! It only lists the ohms resistance for the oil pressure and fuel gauge, which is 90 ohms. My mechanic thinks that since those two gauges list the same ohms resistance specs, that the temp gauge probably has 90 ohms as well. He also said that NAPA or others probably have listings of sending units with different ohms specs and we just need to find one that will match the new gauge.
Have read about others temp gauge problems here, but they were on Monte Carlos and Cutlasses. Don't know if my mechanic has checked the wiring or not. When I pulled the cluster out again after the first time it didn't work, I carefully cleaned the printed circuit area on it and where it meets the dash with a pencil eraser (read that someone said to clean it with that). Was hoping it was just a bad connection.
Hope someone can steer me in the right direction of getting this "pain in the neck" problem solved once and for all! The dash panel has been off the car for years and I want to get it all put back together and start driving and enjoying the car!!!
Thanks very much!
