Stubborn Swan Cap.

[JimG1127]

I have a '29 A. The radiator is shot. Its been repaired at least once before. I need to remove it and replace it with a new one. Problem is the Swan cap won't budge. I removed the tiny hex screw in the back that "locks" the cap on. There are three tabs on the top of the open radiator cap base and I'm tapping it with a screwdriver blade and hammer. Not moving. Do people sometimes weld these on? I'm hoping that I don't have to destroy it. I also cannot get the radiator shell off until the cap comes off.
Interesting side note. I ordered the best heavy duty radiator that Synders has. It arrived today. Its from Brassworks. It looks well made. Ive read mixed reviews about them But more positive than negative.