Volkswagen jetta 00 why does it overhears?

Question

I have a 2000 volkswagen jetta, that for the past month has been overheating, but the water level at the reservoir is plenty. I cannot access the radiator so I can't check for water there.

I don't know if it could be the sensor couse a coupple of months ago it started to drop all the way to the cold side after a 2 and a half hour drive on the highway. But resently it started to go all the way to the overheat side also on the highway, when I slow down for traffic or exit the highway it cools down rapidly but eventually rises again the engine itself don't seem to show any sign of a malfunction like stalling or losing power, and the engine don't seem to feel very hot.

what could be making my car overheat???

Answer 1

Replace your coolant sensor, it's the most likely culprit with the symptoms you describe, and it's a pretty simple DIY.  

You'll also want to check on your water pump. If it hasn't been replaced every 60K, it's also a very likely thing to go wrong. The original water pumps have this plastic impeller that often shatters. Be sure to replace with pump with a METAL impeller.

Answer 2

First there is no radiator cap on a Jetta!!!!!! So some one is wrong. Second open the tank where you put in the coolant (the cap is blue). Then start the car . When you look in the the tank see if the coolant is flowing. If the coolant is still that means that your pump is not working well.You would have to buy a new pump. 3rd are your radiator fans working?

Answer 3

First, replace your radiator cap. It may be on the reservoir/over flow tank.. If the system doesn't keep sufficient pressure, it can cause this fluctuation. If that doesn't cure it, make sure the thermostat isn't sticking open then closed, or just replace it. Thermostats are cheap and so are radiator caps, cheaper than a blown head gasket. Another question is, when was your cooling system last flushed? If it's been a while, this might be a good time to clean out the rust that can accumulate over time.