My 04 saturn ion is making a rattilig noise when engine is runing, it 's louder when put in drive, soungs like something is lose like my exause.

More info - If it only makes the noise when the car is moving its probably a wheel bearing - if it makes a whining noise whether its moving or not it sound like the power steering pump is on its way out - it could be as simple as adding fluid - start the vehicle and while sitting there turn the wheel left and right - the noise should get louder and softer - if it doesnt - its one of the other accessories - a/c pump or the alternator itself -

Check for other loose heat shields.
The shield you removed would allow more noise to enter the cabin too.

Hi, I recently bought a 2005 Saturn Ion and all of a sudden when I accelerate or at least attempt to, I hear "knocking" noise. It gets louder as I press harder on the gas pedal, what does this mean??? Also, my coolant light is on as well, however when we checked the fluids, it was full..will these repairs be pretty costly? And is it even worth getting fixed?

You buy a 10 year old car that isn't even made anymore
and know it has issues

Do you not have a repair shop you use for many years that has
been around for decades

You need a shop to go thru the entire car & fix ALL problems
regardless of cost,not us guessing at things

Not to get up to speed could be a gas filter ,most likely worn
out & blocked exhaust converter & I could write a book

All it's issues can be diagnosed & you should spend about $1500
if ALL problems are properly tested & resolved

Now you got the entire suspension,all fluids,brakes,tires & on & on

When I buy any vehicle I put it on stands for 3 weeks min & go thru it

On a new car i spend a week a year going thru the entire car

I take brakes apart every year

I check all data every 4 months with professional scan tool software

Sounds electrical.

Without hearing the noise, it is hard to diagnose. If you replaced the bearings and the noise level is correlated with the speed of the vehicle - I'd look at the wheels/tires. They may be out of balance or you could have a radial shift in one of the tires. Rotate the back tires to the front and front to back. See if that changes the pitch or noise level.

What does it do when you try to crank the engine again?

it could be a number of reasons. it comes on when a sensor on the engine sences something is not runing right on your motor

I agree. I see sway bar links go bad and make nosie much more often than struts on Ion's. Take it to a service center you trust.

That is simply the mechanism that keeps your car from shifting unless you have the brake applied. It is louder than most vehicles, but that is one small sacrifice for good quality, cheaper car. The noise is normal.