alright so i have a 94 sl2 with 123k miles on it, and there is a rattling noise every time i drive the car, as well as the low coolant light turns on frequently but the engine runs at about 10-11 o'clock average (even when the light is flashing) and on rare occasion will go up to around 12 - 1 o'clock. The rattle will keep happening while the car is on but once the radiator light stops blinking the rattle goes away for a little bit then it all pops back on again. Lastly the car when sitting idle starts to heat up....(till i start driving then it pulls back down to the 10-11o'clock mark) so far the best guess i have is the water pump and accessory belt (water pumps on these guys go out like clockwork at 125k i've heard) any other guesses would be appreciated! thanks guys
Btw im new here im kyle and i've had the saturn for about 8 months now

 

Is the coolant reservoir full or is it actually low on coolant?

 

Sounds like a couple of problems there ... and the term "rattle" could mean a lot of things. Is the engine making the noise, or is the car itself rattling ?? Please comment.

1)Start the car, turn the A/C on to maximum cooling, and the air control to recirculation. Open the hood, and verify that the cooling fan for the engine is operating. If not, troubleshoot (bad fan, blown fuse, broke wire).

2) Examine the passenger side of the engine for coolant leaks, especially from/around the water pump area. If you are not losing coolant, and the overflow tank stays at the proper level, the sensor in the tank may be stuck/defective.

 

the engine is making noise, the cooling fan is operating fine and i just checked and the coolant IS low...its also very bubbly inside of it (like antifreeze foam-ish). I haven't noticed any leaks.....
how difficult is it to change out the sensor?
Also i've gotten one other suggestion and that is the tensioner itself going bad...

 

What you say above leads me to believe you have either a blown head gasket (hence the bubbles), or a cracked cylinder head (much more problem). Pull the oil dipstick, and see if the oil has a "milky" appearance - if it does, more than likely it is a cracked head.

Since the fan is operating properly, the sensor may be OK, but that is a minor issue.

A compression test on the engine will give more information ....

 

I have no idea how to do a compression test, no milky appearance in the oil.
im gonna take it in to have a mechanic friend of mine see what he thinks just to be sure.....in the meantime how do you do the compression test?

 

your gonna want to pull all the spark plugs, pull the fuel pump relay and disable the coil. it helps to have the car at operating temp but isnt always necessary. then with a compression tester, you would thread the hose into one of the spark plug holes, and connect your gauge to the hose. the vehicle should be cranked typically about 5 "puffs" or until the reading on the gauge ceases to increase. dont go overboard cranking the engine for tiny movements of the needle either. do this for all cylinders. also, if you have low compression, a follow up leak down test can help verify your problems. the compression test is a simple test to perform but in all honesty i would have your mechanic friend either do it for you or assist you if your not sure what your doin.

 

I'm pretty darn sure after your "mechanic friend" has a look at your car, and runs the compression test, the verict will be "failed head gasket". He will be able to fix it - provided he has the knowledge and ability

 

The rattling is probably coming from the exhaust heat shield. It's probably loose. Good-luck!

 

Hey Kylockinator, Did u ever figure out what it was?