Well I left in under tension from the gear puller all week with oil to soak down the spines. No luck. Tried tapping on the end of the puller too. Just to make sure, there is nothing that holds the whiper arm in place other than the 13mm nut correct?

If I can't get it off soon I'm probably just going to unplug the dang siren.

 

Nothing but the 13mm nut, and in your case a load of rust/corrosion.
Seriously, have you tried my method of just rocking the arm up and down ? Always works for me ......

 

Yes sir. The whole assembly under the cowl just moves when I rock it.

 

O well. Nothing ventured, nothing gained.

Puller with pressure and banging on it don't work, I know of no other suggestions short of a cutting torch. ( I wouldn't advise heat in this are due to the plastic cowl )

 

Oil?
What kind of oil would that be?

This mixture is supposed to be the cats meow when used as a penetrating fluid.
Acetone and brake fluid or transmission fluid mixed 50/50.
Shake up thoroughly all the time.

Keep the brake fluid off paint as it may mark it up badly.

 

Also acetone and plastic don't play well together .....

 

Try giving it a sharp rap with a rubber mallet, then the puller.

 

Thanks for all the suggestions guys. I couldn't get them off. Tried to remove the siren with the cowl on. That didn't work so I unplugged it, pulled the wire into the engine bay and mounted the new siren behind the heat shield next to the electrical box. I guess we will see how long it lasts with the added engine heat. When it does go, it's getting unplugged.

 

LOL
True, but if it eats a big enough hole in the cowl it will come off with the wiper still attached to the car.

Someplasticis not affected in the short term.

We are not supposed to be spraying the car with this stuff, just a little judiciously applied.