I did the hard way and reached back there and did it myself but it took a couple hours and a lot of work to get to them. I've been told to undo the front motor mounts and with a hydraulic jack, jack the front of the engine down far enough to see the back 3 plugs, but I didn't try that.
A lot of the Gran Prix V-6 (beginning with 3.1 litre v-6 transaxles)models have "dog bone" motor mounts on the front side of the engine. Disconnect these (don't worry the engine is sitting on the transaxle, and it won't fall.) Once the mounts are disconnected you can insert a length of 2x4 between the engine and firewall and rotate the engine forward by using leverage. It will turn with the front drive axle. Just prop the 2x4 in the position you want to hold the engine. Sometimes, depending on your options you may have to disconnect the radiator hoses, but not always. You can usually tell just by looking. Once you have changed the plugs, release the 2x4 and the engine will rotate back to the original position. Reconnect the motor mounts (and radiator hoses if required)and, VOILA! You're done. I've done this several times and it sure beats the labor charge the shop wants to reach those plugs. Got this tip from a Pontiac mechanic.
You must loosen the top motor mount and tilt the engine forward.
The engine must be tilted forward. Why are you changing spark plugs on a 2003 engine. These plugs do not need replacement until 100,000 miles. For more detailed directions, follow the instructions for changing the plugs in any 3800 engine in the grand prix '97 and up listed in the grand prix forum. Hope this helps. "G" You need to remove alternator, and undo forward engine support to get engine to go forward. It is a tight fit but it can be done. I even did it with just alternator removed. Have fun
No special tool. half inch socket and a 13mm. if you have a C-clamp or something to push the calibar back that's all ya need.
underneath the car buy the frame. towards the back part of the car. about where the rear seats are.
Mine is a '92 and the sensor is screwed into the back of the radiator on the passenger side about halfway down.
Look down between the air cleaner and washer fluid reservoir; the two A/C valves are just below the back corner of the battery. At least they are on my '92 Gran Prix.
the plugs on the back are very difficult. How is this done.
Just did mine...........you will need a special tool to push the piston back in. Autozone will let you borrow it for free ($55 deposit)
easy.........take the old spark plugs out and put the new spark plugs back
To change back3 plugs on 1997 OldsmobileI removed the alternator. It is a pain in the ...
Remove the upper intake, then proceed as with the other plugs.
If you look at the top front of the engine you'll see a dog bone shaped motor mount. Most parts stores will rent you tool to help change those plugs. You take that motor mount out, put the tool in it's place and start tightening. It's a threaded tool and as you tighten it it will rock the engine forward allowing you access to the rear 3 plugs.