alrighty...so let me get this straight. You have been getting a LOW COOLANT light yet you did NOT check the coolant level?
Now was this coolant light coming on before or after the "valve job"?
And also once you got the car back from the mechanic for the "valve job" it slams into reverse and foward gears?
I have a feeling you got ripped off. 4 hours for a valve job...HIGHLY unlikely even for a Saturn mechanic. The only way to reach the valves is for the top of the motor to come off (head). To get that off you need to take the Side of the motor off (timing chain cover and chain). Then you need to fix the valve. then put it back together. ALSO if your had a burnt valve you would have seen major smoke and would have had a HORRIBLE running car. Redoing a valve is more work than replacing the ENTIRE motor.
As to your "coolant problem" more than likely you either had a loose hose clamp, radiator crack, or at the very worst a bad headgasket. If coolant is found in the oil than its a head gasket issue. however with 80k on the car i doubt thats it.
What you have NOW is reverse slam. There are a few remedies for it.
1)
"NOTE: This proceedure "can" often cure a delayed engagement or reverse (reverse slam) in
Saturn autotransaxles PROVIDED you have not waited "too long"
DO NOT MAKE UP YOUR "OWN VERSION" follow the instructions exactly...
The "works nearly everytime" cure for the reverse "slam"
1. Change the transaxle fluid and filter (use "conventional" not synthetic fluid)
2. Add your choice of automatic transmission fluid additive (transmedic, Lucas etc...personal choice, Prolong auto transmission additive)
3. Start the
car firmly set the parking brake, chock the wheels and or back it up against a firm immovable object (A brick wall works well)
4. Put the car in REVERSE and LEAVE IT THERE, RUNNING, IN REVERSE, for about 20-30 mins at idle.
What this does is use the clean transaxle fluid and additive to flush out the reverse passage in the valve body by simulating driving in reverse for about 10 miles. IT WILL NOT HARM THE TRANSAXLE OR ENGINE IN ANY WAY. After completing this proceedure, (99 times out of 100) your reverse slam will vanish for at least several months and maybe forever (actually usually forever is a better description) Maintain the transaxle correctly from that point forward. If it initially does not work for long, you can REPEAT the proceedure without changing the clean fluid and sometimes net good results BUT if after 2 tries things have not improved you are probably looking at valve body replacement. YOU MUST CHANGE THE FLUID FIRST! Doing this with "dirty" fluid still in the transaxle may actually make it WORSE. Also "normal" transmissiopn "flushes" WILL NOT cure this problem, as they don't feed enough "warm" clean fluid through the valve body for long enough."
-Wolfman-
2) Input shaft nut is loose. It needs to be tightened to 111ft/lbs
3) A new valve body is needed.
80k on a saturn is a BABY. If treated right by the right people they can last WELL over 200k. I would suggest you find another mechanic as for a "valve job" or any other job that would be effected by the coolant BESIDES removal fo the entire engine....the lower engine mount does NOT need nor should it be touched at all.