I have a 2001 Saturn SL1. Every once in a while the low coolant light comes on. (Usually after a few months). If the engine is hot, when removing the reservoir cap there is no pressure. I drive the vehicle frequently for long periods of time (Up to 3 1/2 hours at a time) and have no issue with the car overheating. No sign of leaking cooling, yet like I said over a few months the fluid will be low again, so it has to have some kind of leak some where. I am thinking maybe something as simple as the reservoir cap, or maybe a manifold gasket or water pump. Plus no coolant is getting into the oil, and no white smoke. Any ideas would be greatly appreciated.

 

I would suspect a very slow waterpump leak. The coolant can evaporate before it hits the ground. It will leave a telltail stain under the pump. You may not see it on the ground until the leak gets worse. A cooling system pressure test pump will let you pressurize the system and inspect for leaks. We often times remove the cap adaptor and tee into a small coolant hose. This will let you test the complete system including the cap at the same time.

 

Thank you, I will take a look at the water pump area this weekend. I will let you know.