Gas cap stuck on, new one no better
 

The gas cap on my 1998 SL 500 just spins when you try to take it off. I was able to get it off with some difficulty using pliers. Put on a brand new one but it just spins as well when you try to take it off. Thoughts????
Baybear

gas cap repair
 

This is a trick I used on another car. Once you get the cap off, drill through the plastic cap and through the first metal portiion of the cap. BE CAREFUL TO NOT DRILL ALL THE WAY THROUGH BOTH INNER METAL CAPS and use a small drill. Use a sheet metal screw to fasten the outer plastic cap to the inner metal part. You will have defeated the "ratchet" function and the cap can be removed and replaced normally.
If you simply can't get the present cap off, do the above in place. By pinning the outer and inner together, you will be able to remove it.

Thanks, but if I do that will it still seal properly to prevent the "Check Engine"
light from coming on?
Baybear

Probably stating the obvious but it sounds like there interference to its loosening, IE: it is too tight. Maybe try to see what is sticking? Either that or the ratchet mechanism is malfunctioning. If you got the new one at the dealer then ask them what is wrong with their part.

gas cap repair
 

Yes it will still seal so long as you don't drill all the way through the inner part of the cap also. I guess the purpose of that ratchet mechanism is an EPA thing to prevent venting into the atmoshere when removing the fuel cap. It is a stupid mechanism I think. If it is required they should make it of metal instead of cheap plastic so it will stay together.