I just need some quick advice from the experts. My teenage son drives our old Mitsubishi Expo LRV. I noticed yesterday when riding with him that:

1. The temperature gauge stays pinned in the coldest position
2. The car is slow to heat up, but the heater does eventually work
3. The coolant reservoir was empty

I added coolant and, with the engine running, it only required about a quart to fill the overflow reservoir from completely empty to the "full" line. This did not change the problem with the low temperature indication. My son also noted last night that the car wanted to stall easily in idle when warm. Today, it runs just fine.

I should add that it is about 15 degress F here right now.

Is this simply a faulty temperature sender, or should I be worried about the thermostat, water pump, or other components of the cooling system? :confused: :confused:

hmm... sounds like maybe a bad sending unit?

When you crank the car the gauge should move... probly to the highest point & then back down to cool.
If the gauge doesnt move id say you need to replace the sending unit...
Normal it is easy to replace... one small nut on the side or top of the engine block.

how many miles on the Mitsu? Did you add coolent to the radiator as well or just to the overflow rez?, I would put money that the thermostat is telling you something pick one up and have it handy. As you know if the car is warm the coolent is warm no matter what the gauge says so because it seems to be an intermittent problem be ready to replace the thermostat.