Noise and then overheating

A few months ago I noticed what sounded like the cooling fan running really loud - especially when I was driving. When I'd come to a stop, it would slow down, get more quiet, and then stop. It's done this maybe 4 or 5 more times since then, but it always seems to go away if/when I shut off the car and turn it back on. Today I was driving and I heard the noise, but I was about 2 minutes from home so I kept going. All of a sudden the temperature guage went all the way over to hot and it indicated the car was overheating and something about lack of power. It seems likely these two issues are related. Thoughts?

A few months ago I noticed what sounded like the cooling fan running really loud - especially when I was driving. When I'd come to a stop, it would slow down, get more quiet, and then stop. It's done this maybe 4 or 5 more times since then, but it always seems to go away if/when I shut off the car and turn it back on. Today I was driving and I heard the noise, but I was about 2 minutes from home so I kept going. All of a sudden the temperature guage went all the way over to hot and it indicated the car was overheating and something about lack of power. It seems likely these two issues are related. Thoughts?
make a visual check first from your description it could be a number of things check your belts hoses fan assy etc.

When your LS detects and overtemp condition, it will shut off fuel and spark to some of the cylinders and just pump air in them, acting as a heat pump. This helps cool the engine and obviously leads to reduced power.

Have you checked your coolant level to see if it is still full or now? Also, pull your engine oil dipstick and pay attention to the condition of the oil. If the oil looks like chocolate milk, you may have a bad head gasket, cracked block, or bad intake manifold gasket (I don't know if oil goes through the intake gasket or not).

Hopefully you just are low on coolant or have an air pocket in the coolant causing the cooling fan to run sporatically and causing the gauge to move as rapidly as it did.

-Rod

Pianoman, I hope you figure this out because I have the same exact problem with my 2000 ls, have had it for 2 years. Sometimes it does it sometimes it doesn't. If you take the cap off the overfill tank very slowly it will quickly reduce the temp and you can get on your way, but this is only a temporary fix. Please let me know what you come up with