i just replaced the thermostat because i though it was the problem, but it didnt change, i have a 96 ls, it doesnt overheat on the gauge in the car, but the lines get really hot and so does the whole engine bay, and it starts smoking,

how would i know if the water pump is bad? could that be the problem? any ideas

 

check the radiator fan fuse, located beside the battery in the engine bay. could be blown.

 

is your fan even coming on?

 

figure it out yet? I got the same problem, my overflow tank boils but the needle on my gauge doesn't move past half. Fan doesn't come on and it's a full radiator, not a half.

let me know what was wrong with urs if u fixed it

 

dark it sounds like you need a new rad cap