2001 Oldsmobile Intrigue GX temperature rising at idle and drops when accelerating

Good evening, morning, or afternoon (your timezone). I have a 2001 Oldsmobile Intrigue GX that has close to 119,600 miles on it, no coolant in the oil, no oil in the coolant, no white smoke, and no leaks after replacing the coolant recovery tank (the old tank had a crack at the return inlet when I was attempting to remove the hose so I can move the tank out of the way when replacing the power steering pump. When I would stop at a red light or a stop sign for a long time when I’m on my way to any place (work, home, thrift stores, and so on), I notice that the temperature gauge goes past the 1/2 marker and a couple of times, it went past or at the 3/4 marker, but, when I accelerate after waiting to turn on or going straight through a green light, or turning right on red (if there’s a no turn on red sign)/going through a stop sign, the temperature drops to the 1/2 marker or below.

I notice that the cooling fans aren’t kicking on, which I believe might be the issue right there, however, before I got the crimped hose fixed on my car several months ago, the fans would kick on past the 3/4 marker and it did overheat once before. Once I get home from work or on Friday, I’ll be checking the relays and the contact points for any issues. The fuses for the cooling fans are still good, however, it might be another issue. Would the temperature sensor cause the temperature gauge to rise up and go back down (fluctuate) or an air trap? Also, on my car, how do I go about airing out the cooling system easily? The car only has 1 radiator cap and that’s on the recovery tank, but, there is a screw plug above the lower radiator hose.

I can only refer you to what I told this poster.

If there’s air trapped in the cooling system, don’t expect the coolant temp sensors, heater, gauges, or fans to work correctly.


A granddaughter had a 93 Buick Regal with the radiator cap mounted on a remote tank on the fender that was difficult to bleed. I found out it was helpful to unbolt the tank and hold it as high as the hose would let it with the engine running while slowly adding coolant.

From what I see on the 3.5L V6 VIN H engine the radiator fan(s) should come on low speed at 220 deg F and high speed at 230 deg F. The PCM is what turns them on, based on the engine coolant temperature it senses, and other factors such as the AC system. A scan tool will tell you what the PCM thinks the coolant temp is. The filling procedure is to open the radiator bleed valve, add the coolant, close the bleed screw when coolant starts coming out, then continue to fill to the cold mark. Next idle the engine and continue to fill to the full mark. After engine reaches normal operating temp, turn engine off and wait two minutes, then add coolant to the full mark as required. install the surge tank cap, then continue to verify the coolant level is ok, and the freeze protection is ok. If the fans are working correctly but it still overheats, air in the cooling system, failure to hold operating pressure thermostat problems, and a water pump on the fritz can all cause this symptom.


after you make sure the air is purged from the system, turn the AC on. The fans should come on when you turn on the AC. If they do come on, this will rule out the fans and at least one relay as being faulty.

Good idea on the water pump and other things. I might as well replace the water pump (will flush the cooling system twice), the thermostat with the housing, and replace the idler and belt tentioner pulley or the whole belt tensioner assembly. Fortunately, I have the correct torque specs for everything and would it be a good idea to replace the temperature sensor as well as a preventative maintenance measure? Thank you for the tips. The fans sound like they run with the A/C on, but, I should do the fan test by placing two pieces of paper attached to a pipe using tape and see if the fans spin up with the A/C running or not.

Also, for the fuel system, I have a code P0446 (EVAP circuit) and on the BlueDriver Diagnostics app on my phone that says replace the Fuel Tank Pressure (FTP) Sensor on the fuel pump or the EVAP Vent Solenoid (not clogged and I can fill up my car without issues, thankfully) and the fuel gauge also isn’t working (high output on the float sensor). Should I replace just those parts, the fuel pump, or check the connections and fix them? I know I have to depressurize the fuel system prior to removing the fuel pump (fortunately, an easy access to the fuel pump by folding the rear seats down and moving the paneling that covers the access door). Average gas mileage when I calculated it last time was 20.63MPG (0.63 over the 20MPG average).