where can I buy a new pressure cap for my steam buggy ?

I just fixed mine!
You probably don't need a new cap.
The cap has a safety valve in it, to release steam if the pressure gets too great. It has.
Most likely, the pressure is caused from a buildup of minerals in your water, at the nozzle tip. That's where the REAL problem is.
Remove all attachments from the pistolgrip part. Pull out the chrome-plated cap on the nozzle and clean it with a pipe cleaner.
Then run a pipe cleaner down the plastic tube it fits in. Once you have cleared this tube, put some water in the buggy's tank and turn it on. Aim it somewhere you don't care about. The steam pressure will drive the minerals out. Wait for it to cool, put the chrome nozzle back on and your ready to go!

Tenorlord
July 2008